JP2000118268A - Driving force controller for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase in the opening degrees of a throttle even if an N range is set during control for realizing a requested driving force by the combination of an optimal engine revolting speed and an engine output. SOLUTION: A requested horse power HPs is obtained from a requested driving force Ts and an axle rotational speed Ns calculated from an accelerator depressing amount APS and a car speed VSP, and a target engine output Te* generating this HPs at a minimum fuel cost and a transmission target input rotational speed Npri* are calculated based on an engine characteristic curve. A neutral engine output target value TeH reduced with the increase of an engine revolting speed Ne is calculated for each APS, and in an N range, TeH is used for the operation of a target throttle opening degree TVO* instead of Te*. Thus, even if Ne is increased caused by the N range during driving force control for realizing Ts at a minimum fuel cost, by output control for realizing TeH, the unlimited increase of the opening degree of the throttle is prevented.

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 apparatus for a vehicle in which a required axle driving force of a vehicle equipped with a continuously variable transmission can be generated by a combination with an optimum engine output and a gear ratio. More particularly, the present invention relates to a driving force control device for a vehicle that can perform useful operations when a continuously variable transmission is set to a neutral range during traveling or is returned to a traveling range thereafter.

[0002]

2. Description of the Related Art A continuously variable transmission represented by a V-belt type continuously variable transmission or a toroidal type continuously variable transmission generally determines a target gear ratio from an engine required load and a vehicle speed. Shift control is performed to achieve the target gear ratio. Therefore, during acceleration in which the driver depresses the accelerator pedal to increase the required engine load, the target gear ratio is changed to be larger (to be a lower speed gear ratio), and the continuously variable transmission is set to the increased target gear ratio. When the vehicle is downshifted to the gear ratio, and conversely, during a low-load operation in which the driver returns the accelerator pedal to reduce the required engine load, the target gear ratio is changed to be smaller (to be a higher gear ratio). The continuously variable transmission is upshifted to the reduced target gear ratio.

On the other hand, as a technique for obtaining a required driving force of a vehicle, there is a technique described in, for example, JP-A-7-172217. This technology calculates the target driving force of the vehicle from the vehicle speed and the amount of accelerator pedal depression,
The required driving force to be transmitted to the wheels is added to the running resistance that can be estimated from the vehicle speed.

[0004] By the way, in the above-mentioned conventional speed change control of a continuously variable transmission, the required driving force obtained by the technique disclosed in the above-mentioned literature cannot be accurately realized. In any case, it is impossible to realize the required driving force in such a manner that the fuel efficiency of the engine is minimized.

For example, in order to achieve the required driving force in such a manner that the fuel efficiency of the engine is minimized, the required driving force is controlled by controlling the output of the engine and the shift control of the continuously variable transmission (the engine speed). Control) that can be realized by an optimal combination with the vehicle control.

A driving force control system for this purpose requires, for example, the required minimum axle driving force by the method described in Japanese Patent Laid-Open No. 7-172217, based on the driving state and running conditions of the vehicle such as the vehicle speed and the amount of depression of an accelerator pedal. , And the optimum combination of the target engine speed and the target engine output for realizing the required axle driving force at, for example, the lowest fuel efficiency is obtained, and the continuously variable transmission target input speed corresponding to the target engine speed is obtained. A driving force control device that controls the speed of the transmission and controls the output of the engine by operating the throttle opening to achieve the target engine output is conceivable.

[0007]

Incidentally, the optimum combination of the target engine speed and the target engine output for achieving the required axle driving force as described above is determined, and the continuously variable transmission is designed to realize these. It has been confirmed that the driving force control device that controls the shift and controls the throttle opening (engine output) of the engine has the following problems.

The output (torque) characteristic of the engine is determined by the throttle opening and the engine speed. The larger the throttle opening, the higher the engine output (torque), and the higher the engine speed, the higher the engine output (torque). Becomes larger. Therefore, even when the same target engine output is realized, the target throttle opening for that purpose increases as the engine speed increases. Therefore, while the throttle opening (engine output) control is being performed, the driver sets the continuously variable transmission from the traveling range to the neutral range where power cannot be transmitted, or the failure causes the continuously variable transmission to be unable to transmit power. In the neutral state, the throttle opening (engine output) control is performed according to the target engine output determined regardless of the engine speed, even though the engine is in a no-load state. However, no matter how small the throttle opening is, the throttle opening is controlled to increase steadily as the engine speed increases due to the no-load condition of the engine. Raises.

According to the first aspect of the present invention, even if the above-mentioned problem is caused by no engine load, the normal target engine output determined irrespective of the engine speed is continuously used as the engine output (throttle opening degree). It is an object of the present invention to solve the above-mentioned problem by contributing another engine output target value to the engine output control when the engine is not loaded based on the fact that it contributes to the control.

[0010] A second aspect of the present invention is to propose a preferable method of obtaining the another engine output target value so as to make the operation and effect of the first aspect remarkable.

According to a third aspect of the present invention, when the other engine output target value to be given in the engine output control in a no-load state is a constant accelerator pedal depression amount, the engine speed is increased. It is an object of the present invention to propose a driving force control device embodying this idea from the viewpoint that the above problem can be solved by reducing the size as the size decreases.

A fourth aspect of the present invention is to propose a driving force control device capable of obtaining the another engine output target value more easily.

According to a fifth aspect of the present invention, even when the continuously variable transmission returns from the neutral state to the power transmission enabled state, the engine is maintained until the friction element for performing the return completes the engagement. Is in a no-load state, and still causes the above-mentioned problem relating to the engine speed rising. Therefore, the other engine output target value is continued to be used for the engine output control during this time, so that the engine speed rising at the time of the return. It is an object of the present invention to propose a driving force control device that can also avoid the above.

According to a sixth aspect of the present invention, there is provided a driving force control apparatus capable of inexpensively determining completion of engagement of a friction element without relying on a rotation sensor in the fifth aspect. .

According to a seventh aspect of the present invention, in the driving force control apparatus according to the fifth aspect of the present invention, the completion of the engagement of the friction element can be reliably determined based on the output from the rotation sensor even when a torque converter is present. The purpose is to propose.

[0016]

For these purposes, a vehicle driving force control apparatus according to a first aspect of the present invention comprises an engine capable of arbitrarily changing the output by factors other than the operation of an accelerator pedal, and a continuously variable transmission. A vehicle equipped with a power train that is a combination of a target engine speed and a target engine output for realizing a required axle driving force determined by the driving state and running conditions of the vehicle. A drive force control device for a vehicle, which controls the speed of the continuously variable transmission so as to have a transmission target input rotation speed corresponding to the engine rotation speed and controls the output of an engine so as to have the target engine output. When the continuously variable transmission is brought into a neutral state where power cannot be transmitted during traveling, the engine is also driven in the neutral state instead of the target engine output. The never caused racing of the neutral rotational engine output target value is characterized in that it has adapted to contribute to the engine output control.

According to a second aspect of the present invention, there is provided a driving force control device for a vehicle.
In the first invention, the neutral engine output target value is obtained based on a predetermined characteristic from an accelerator pedal depression amount and an engine speed.

According to a third aspect of the present invention, there is provided a driving force control apparatus for a vehicle.
The predetermined characteristic according to the second aspect of the invention is characterized in that the characteristic of the neutral engine output target value with respect to the accelerator pedal depression amount is assigned so that the neutral engine output target value decreases as the engine speed increases. Things.

A vehicle driving force control apparatus according to a fourth aspect of the present invention
In the first invention, the target engine output limited in accordance with the engine speed is configured to be the neutral engine output target value.

According to a fifth aspect of the present invention, there is provided a driving force control device for a vehicle.
In any one of the first invention to the fourth invention, when the continuously variable transmission returns from the neutral state to the power transmission enabled state, until the friction element for performing the return completes the engagement, The neutral engine output target value is configured to contribute to the engine output control.

A vehicle driving force control apparatus according to a sixth aspect of the present invention
In the fifth invention, it is configured that the friction element is determined to have completed the engagement when a set time has elapsed after a command to change the continuously variable transmission from a neutral state to a power transmission enabled state is issued. It is a feature.

A vehicle driving force control apparatus according to a seventh aspect of the present invention
In the fifth invention or the sixth invention, when the torque converter between the continuously variable transmission and the engine is in a lockup state in which an input / output element is directly connected, the transmission input rotation speed matches the engine rotation speed. It is characterized in that the friction element is configured to determine that the fastening has been completed with time.

[0023]

According to the first aspect of the present invention, an optimum combination of the target engine speed and the target engine output for realizing the required axle driving force determined by the driving state and the running conditions of the vehicle is determined, and the target engine speed is determined. Driving force control is performed to control the speed of the continuously variable transmission so as to achieve the corresponding transmission target input rotation speed and to output-control the engine so as to achieve the target engine output. The output from the engine controlled as described above is shifted by the continuously variable transmission controlled to shift as described above and becomes the output of the power train.

When the continuously variable transmission is brought into a neutral state in which power cannot be transmitted due to range switching or a failure while the vehicle is running under such driving force control, the engine is not driven in the neutral state but in the neutral state. A neutral engine output target value that does not cause the rotation to rise up contributes to engine output control. Therefore, even when the continuously variable transmission is set to the neutral state during traveling, the above-mentioned problem related to the engine speed up which has conventionally occurred by using the target engine output determined independently of the engine speed. Can be reliably eliminated.

In the second aspect of the invention, the neutral engine output target value is obtained from the accelerator pedal depression amount and the engine speed based on predetermined characteristics. Therefore, the neutral engine output target value can be easily obtained by searching a map. In addition to being able to be obtained, it can be made accurate that matches the driving conditions.

In the third invention, the predetermined characteristic in the second invention is assigned to the characteristic of the neutral engine output target value with respect to the accelerator pedal depression amount such that the neutral engine output target value decreases as the engine speed increases. The neutral engine output target value
Under the same accelerator pedal depression amount, the value decreases as the engine speed increases, and the above-described problem relating to the engine speed rising can be more reliably solved.

In the fourth aspect of the present invention, the target engine output limited in accordance with the engine speed is used as the neutral engine output target value. Therefore, the neutral engine output target value can be obtained more easily, which is a great advantage. It is.

In the fifth invention, when the continuously variable transmission returns from the neutral state to the power transmission enabled state, the output of the continuously variable transmission is continuously changed to the target engine output until the friction element for performing the return completes the engagement. Thus, the neutral engine output target value contributes to engine output control. That is, even when the continuously variable transmission returns from the neutral state to the power transmission enabled state, the engine is in a no-load state until the above-described friction element completes engagement, and during this time, the target engine output is used for engine output control. Although the above-mentioned problem relating to the increase in engine speed still occurs when used, the engine speed increase during the return can be reduced by continuing to use the neutral engine output target value instead of the target engine output for engine output control. Can also be avoided.

In the sixth aspect of the present invention, when the completion of the engagement of the friction element is determined, the friction element is activated when a set time has elapsed after a command for changing the continuously variable transmission from the neutral state to the power transmission enabled state is issued. Since it is determined that the fastening has been completed, it is advantageous that the completion of the fastening of the friction element can be determined at low cost without relying on the rotation sensor.

In the seventh aspect of the present invention, when judging the completion of the engagement of the friction element, when the torque converter between the continuously variable transmission and the engine is in a lockup state in which the input and output elements are directly connected, the transmission input is determined. When the rotational speed matches the engine speed, it is determined that the friction element has been engaged, so even if there is a torque converter between the continuously variable transmission and the engine, the output of the rotation sensor ensures the engagement of the friction element. Completion can be determined.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a power train of a vehicle provided with a driving force control device according to an embodiment of the present invention and a control system thereof, and the power train includes an engine 1 and a continuously variable transmission 2. The engine 1 is composed of an internal combustion engine, but is not linked to an accelerator pedal 3 operated by a driver, but is separated from the accelerator pedal 3 and has a throttle valve 5 whose opening is electronically controlled by a step motor 4. Set the motor 4 to the target throttle opening (T
By setting the rotational position in accordance with the VO ^* ) command, the throttle valve 5 is set to the target throttle opening TVO ^* , so that the output of the engine 1 can be controlled by factors other than the operation of the accelerator pedal.

The continuously variable transmission 2 is a well-known V-belt type continuously variable transmission, in which a primary pulley 7 which is drivingly connected to an output shaft of the engine 1 via a torque converter 6 and a starting clutch 15 is arranged in line with the primary pulley. Secondary pulley 8
And a V-belt 9 stretched between these pulleys. Here, the starting clutch 15 is built in a forward / reverse switching mechanism inserted between the torque converter 6 and the primary pulley 7, and is engaged during forward driving to transmit forward rotation to the primary pulley 7; There is a reverse pulley that is engaged and transmits reverse rotation to the primary pulley 7, and when the forward start clutch and the reverse start clutch are both disengaged, the primary pulley 7 is separated from the torque converter 6 to be continuously variable. Although the transmission is set to a neutral state in which power cannot be transmitted, the forward / reverse switching mechanism is not shown in FIG. 1 for convenience, and these clutches are shown as one starting clutch 15 for convenience. Accordingly, the starting clutch 15 constitutes a friction element for bringing the continuously variable transmission into a neutral state or a power transmitting state. The differential clutch device 11 is drivingly connected to the secondary pulley 8 via the final drive gear set 10. To rotate a wheel (not shown).

In order to shift the continuously variable transmission 2, one of the flanges forming the V-grooves of the primary pulley 7 and the secondary pulley 8 is relatively moved closer to the other fixed flange. The width of the V-groove can be reduced by moving the movable pulley, and the width of the V-groove can be increased by separating the two pulleys from the primary pulley pressure _Ppri and the secondary pulley pressure from the hydraulic actuator 12 that responds to the target gear ratio (i ^* ) command. by displacing to a position corresponding to P _sec, and as it can be continuously variable to the continuously variable transmission 2 is the actual gear ratio matches the target gear ratio i ^*.

The target throttle opening TVO ^* and the target gear ratio i ^* are calculated and obtained by the controller 13 which also controls the lock-up of the torque converter 6 and the engagement / disengagement of the starting clutch 15.
Therefore, the controller 13 sends a signal from the accelerator pedal depression amount sensor 14 for detecting the depression position (accelerator pedal depression amount) APS of the accelerator pedal 3 and a signal from the throttle opening sensor 16 for detecting the throttle opening TVO. A signal from a primary pulley rotation sensor 17 for detecting the rotation speed (primary rotation speed) _Npri of the primary pulley 7 and a signal from a secondary pulley rotation sensor 18 for detecting the rotation speed (secondary rotation speed) _Nsec of the secondary pulley 8. Signal, a signal from a vehicle speed sensor 19 for detecting a vehicle speed VSP, and an engine speed N
_e from the engine rotation sensor 20 and an inhibitor switch 2 for detecting the selected range of the continuously variable transmission.
1 and a signal from a start clutch engagement determination circuit 22 for determining whether the engagement of the start clutch 15 is completed.

The starting clutch engagement determining circuit 22 is controlled by the controller 13 to select a range signal from the inhibitor switch 21, a primary pulley rotational speed ( _Npri ) signal from the sensor 17, and an engine rotational speed (N _e ) from the sensor 20. ) Signal or a lock-up (L / U) signal for the torque converter 6, the completion of engagement of the starting clutch 15 is determined by the configuration of FIG. 2 or FIG. 3.

First, the start clutch engagement determination circuit of FIG. 2 will be described. In response to the selection range signal, the changeover switch 31 assumes a solid line position in the neutral (N) range and a broken line position in the travel (D) range. Becomes Here, when the changeover switch 31 is switched from the solid line position to the broken line position by switching from the neutral (N) range to the traveling (D) range, the initial value T is set in the block 32 during the neutral (N) range.
The timer TM that has been given M _S starts subtraction in block 33, and the timer subtraction value is stored in block 34 for use in the next subtraction in block 33. This by the timer TM has become 0 when it is detected in block 35, that is, the starting clutch 15 when a neutral to (N) running from the range (D) from the initial value is switched instantaneously to range (set time) TM _S has passed It is determined that the engagement has been completed, and a start clutch engagement signal is output. In this case, the completion of the engagement of the starting clutch 15 can be determined without relying on a signal from the rotation sensor, and although there is a slight disadvantage in accuracy, the purpose can be advantageously achieved at a low cost.

Next, the start clutch engagement determination circuit of FIG. 3 will be described. In this embodiment, a block 36 and a changeover switch 37 are provided in addition to those of FIG. The changeover switch 37 is locked up (L / U)
When the signal is present and the torque converter 6 is in the lock-up state in which the input and output elements are directly connected, the position becomes the solid line position, and the determination result from the block 35 described above with reference to FIG. A start clutch engagement signal is output. Block 36, a primary pulley rotational speed N _pri is determined whether matches the engine speed N _e, the starting clutch 15 is determined to have completed the fastening outputs a starting clutch engagement signal when they match.

The starting clutch 15 is controlled by the block 36.
When the lock-up (L / U) signal does not exist, the changeover switch 37 is turned on when the torque converter 6 is in the lock-up state. and the broken line position, and the use of simple method for outputting a starting clutch engagement signal when the neutral as previously described per Fig. 2 (N) running from the range (D) set from the switching instant to the range time TM _S has elapsed I do. When the completion of the engagement of the starting clutch 15 is determined, the completion of the engagement may be determined when the operating oil pressure of the starting clutch 15 rises to a value indicating the completion of the engagement of the clutch.

Based on the input information including the starting clutch engagement signal from the starting clutch engagement determination circuit 22, the controller 13 controls the speed change of the continuously variable transmission 2 as shown in the functional block diagram of FIG. The throttle opening control of the engine 1 is performed as follows, and the driving force control of the vehicle targeted by the present invention is executed. The requested axle driving force calculation unit 41 calculates the accelerator pedal depression amount APS detected by the sensor 14 and the vehicle speed V detected by the sensor 19.
Based on the SP, a required minimum axle driving force T _S according to the driving state and running conditions of the vehicle is determined by a method described in, for example, Japanese Patent Application Laid-Open No. 7-172217.

The axle rotation speed calculating section 42 detects the
Detected secondary rotation speed N_secThat is, the transmission output
The number of rotations is adjusted to the gear ratio (final
Final drive gear ratio) i_FBy dividing by
And the current axle speed N_SAsk for. And demand horsepower performance
The calculating unit 43 calculates the required axle drive obtained as described above.
Force T _SAnd axle speed N_SRequired HP by multiplying by_S
Is calculated.

Transmission target input speed and target engine output
In the arithmetic unit 44, FIG.
Based on the engine characteristic diagram shown in
Horsepower HP_SOptimal engine to generate
Gin rotation speed N_eTarget value N_e ^*And target engine output
T_e ^*And then the target engine speed N
_e ^*The transmission target input speed (target primary
Number of rotations) N_pri ^*Ask for.

FIG. 7 shows the engine speed N_eAnd d
Engine output (torque) T_eThe fuel consumption rate is the same
And the output horsepower is the same.
The iso-horsepower line β.
The lowest fuel consumption line connecting the points where the fuel consumption rate improves is indicated by δ.
It was done. In FIG. 7, the required horsepower HP_STo
The intersection of one corresponding horsepower line β and the lowest fuel consumption line δ
For example, if it is point Z in FIG. 7, the required horsepower HP_SThe most
Optimal target engine speed N to generate at low fuel consumption
_e ^*And target engine output T_e ^*The combination of the figure
As shown in Fig. 7, the scale is lowered from point Z to the horizontal and vertical axes
Value.

In the vehicle equipped with a continuously variable transmission, the torque converter 6 is in a lock-up state in which the input and output elements are directly connected for most of the time during power transmission. and the handling of input rotational speed N _pri ^* for convenience equal to the target engine speed N _e ^*.

The transmission target input rotation speed N _pri ^* is input to a target gear ratio calculation unit 45, which divides the transmission target input rotation speed N _pri ^* by the transmission output rotation speed N _sec . As a result, the target speed ratio i ^* corresponding to the transmission target input speed N _pri ^* is obtained and output to the hydraulic actuator 12 as shown in FIG.
^* , That is, the speed change control is performed so that the target input rotation speed _Npri ^* is achieved.

On the other hand, the target engine output _Te ^* from the calculating section 44 is supplied to one input terminal of a changeover switch 46, and the other input terminal of the changeover switch 46 is supplied from the neutral engine output target value calculating section 47 to the other input terminal. The neutral engine output target value _TeH is supplied. And arithmetic unit 4
7 retrieves the neutral engine output target value T _eH based on map corresponding to the characteristics of the planned illustrated in FIG. 10 from the accelerator pedal depression amount APS and the engine speed N _e. Thus the characteristics of the neutral engine output target value T _eH illustrated in Figure 10, the neutral engine output target value T _eH every accelerator pedal depression amount APS is the engine speed N _e
As it rises,
It is assumed that the engine output target value is decreased when the continuously variable transmission is neutralized during traveling and the engine speed is increased, in other words, at this time, the throttle opening control for engine output control is performed. The throttle opening is not increased to any extent, so that the problem of the engine speed rising is eliminated.

The changeover switch 46 is turned on at block 48
The selected range is the neutral (N) range (start clutch 1
5 is in the released state) or during block 4
At 9,50, from neutral (N) range to driving (D) range
Even if there is a switching command, the starting clutch 15 is still engaged.
While it is determined that the completion has not been detected,
The neutral engine output target value T from the arithmetic unit 47_eHTo
Engine output control data T _eTAnd traveling (D) other than the above
Start range that should be concluded in the D range
The changeover switch 4 while the latch 15 has completed the fastening.
6 is set to the position indicated by the broken line, and
Force T_e ^*To engine output control material T_eTFunction to
Shall be.

The engine output control data _TeT obtained as described above is input to the target throttle opening calculating section 51,
The calculation unit 51 obtains the target throttle opening TVO ^* such that the engine output control data _TeT is generated, and obtains the target throttle opening TVO ^* in FIG.
Is output to the step motor 4 to control the opening of the throttle valve 5 so as to reach the target throttle opening TVO ^* .

[0048] According to the present embodiment as described above, in the running (D) range starting clutch 15 is in the engaged state, the target engine output T _e from the calculating unit 44 changeover switch 46 is in the broken line position ^{Since *} is the engine output control data _TeT , the shift control (i ^* ) of the continuously variable transmission is performed in such a manner that the required axle driving force T _S is generated with minimum fuel consumption.
And engine throttle opening control (TVO ^* ).

By the way, when the starting clutch 15 is released,
While the range is in the N range that sets the gearbox in the neutral state,
Start clutch 1 just after switching from J to D range
5 is not completed, that is, the engine is not negative
While in the loaded state, the changeover switch 46 is
And the target engine output T _e
^*, The neutral engine output target value from the arithmetic unit 47
T_eHTo engine output control material T_eTAnd then inside
Standby engine output target value T_eHAs illustrated in FIG.
Engine speed N_eDecrease as
Therefore, the following operation and effect can be achieved. In other words, stepless
The transmission has been set to the N range and neutralized while running.
And the starting clutch 15 is still engaged even when returning to the D range.
While the continuously variable transmission is in a neutral state because it has not been completed
Means that the engine has no load and
The engine speed due to the no-load condition.
When rising, the neutral engine output target value T_eHWas reduced
At this time, throttle opening for engine output control
How much control increases the throttle opening
And the engine speed
Problem can be solved.

FIG. 5 shows another embodiment of the present invention. In the driving force control device shown in FIG. 5, the transmission target input rotation speed N _pri ^* and the target engine output _Te ^* are determined by using the above-described embodiment. Unlike the above, it is determined as follows. The required minimum axle driving force T obtained by the required axle driving force calculation unit 41 based on the accelerator pedal depression amount APS and the vehicle speed VSP.
_S is input to the transmission target input rotation speed calculation unit 61, and the vehicle speed detection value VSP from the sensor 19 is further input to the calculation unit 61.

The transmission target input rotational speed calculation unit 61 corresponds to, for example, data shown in FIG. 9 obtained from the required axle driving force T _S and the vehicle speed VSP based on the characteristic diagram of the engine shown in FIG. based on the map to obtain the target value N _e ^* of the engine speed N _e for generating a current vehicle speed VSP under the required transaxle force T _S at the lowest fuel consumption, then the target engine speed N _The transmission target input rotation speed (target primary rotation speed) _Npri ^* corresponding to _e ^* is obtained, which contributes to the calculation of the target speed ratio i ^* in the calculation unit 45.

Here, the data of FIG. 9 will be described. This data is obtained from the characteristic diagram of the engine shown in FIG. 7 in the following manner. The vehicle speed VSP, the axle driving force T _S, and the engine speed N _e And the relationship. Figure 7 is already mentioned above, the engine speed N _e, the relationship between the engine output (torque) T _e, as iso-fuel consumption lines α fuel consumption rate becomes the same, also, equal horsepower output horsepower becomes the same The minimum fuel consumption line connecting points at which the fuel consumption rate is the best on each isohorsepower line β is indicated by δ. As in Figure 8 the individual points on a minimum fuel consumption line δ shown in FIG. 7, the gear ratio of the vehicle speed VSP to the engine speed N _e by (about including coefficients which), also the engine output (torque) to T _e transaxle marked shift to the two-dimensional coordinate system by replacing the force T _S, when determining the combination of vehicle speed VSP and the engine output (torque) T _e of the lowest fuel consumption per speed ratio, becomes a as shown in FIG.

[0053] When the plots points engine speed N _e to the diagram characteristic line for each gear ratio is equal, in the case of certain engine speed N _e, it is assumed such indicated by A in FIG. 8, these points signed a, indicating the relationship between the vehicle speed VSP and the axle drive force T _S for each engine speed N _e, 7
Can be represented by a line as shown in FIG. In FIG 9, for convenience, it was denoted the engine speed N _e as the target engine speed N _e ^*. The vehicle speed VSP, the axle driving force T _S, and the target engine speed N _e
According to the data representing the relationship with ^* , the case where the combination of the current vehicle speed VSP and the axle driving force T _S corresponds to, for example, the point Z will be described. The target engine speed _Ne ^* for generating _S at the lowest fuel consumption can be obtained as a parameter value (engine speed) related to a line passing through the point Z in FIG. In a vehicle with a continuously variable transmission, the torque converter 6 is in a lockup state in which the input and output elements are directly connected, for most of the time during power transmission.
Although shown in FIG. 9 in the illustrated embodiment, the transmission target input rotation speed (target primary rotation speed) _Npri
^* Is treated as the same value as the target engine speed N _e ^* .

On the other hand, in the present embodiment, the primary pulley rotation speed (transmission input rotation speed) _Npri detected by the sensor 17 in the wheel drive system actual speed ratio calculation unit 62 is used to calculate the axle rotation speed from the calculation unit 42. By dividing by the number N _S , the wheel drive system actual speed ratio i _T is calculated, and the target engine output calculation unit 63 divides the required axle driving force T _S from the calculation unit 41 by the wheel drive system actual speed ratio i _T. by obtains the request target engine output for the axle drive force T _S realized with minimum fuel consumption (torque) T _e ^*, the corresponding input terminal of the target engine output (torque) T _e ^* a changeover switch 46 To supply. Here, the target engine output (torque) T _e ^* is a value corresponding to the torque scale value on the line drawn down from the point Z to the vertical axis in the example of FIG. 7. Are the same.

Also in this embodiment, the starting clutch 1
In the driving (D) range where 5 is engaged,
The changeover switch 46 is set to the broken line position and the
Target engine output T_e ^*To engine output control material T_eTWhen
The required axle driving force T _SGenerate with minimum fuel consumption
Control of the continuously variable transmission (i^*) And en
Gin throttle opening control (TVO^*Can do
Wear.

Also, while the start clutch 15 is released and the continuously variable transmission is in the neutral state during the N range, or while the start clutch 15 has not yet completed engagement immediately after switching from the N range to the D range. That is, while the engine is in the no-load state, the changeover switch 46 is set to the solid line position, and the neutral engine output target value from the arithmetic unit 47 is replaced with the target engine output _Te ^* from the arithmetic unit 63. T _{eH
Is used} as the engine output control data _TeT , the throttle opening control for the engine output control does not increase the throttle opening to what extent when the engine speed increases due to the no-load condition. It is possible to solve the problem related to the engine speed rising.

FIG. 6 shows still another embodiment of the present invention. In this embodiment, the neutral engine output target value calculating section 47 basically performs the above-mentioned construction of FIG. In this embodiment, the neutral engine output target value _TeH is obtained by a method different from the above embodiment. That is, in the present embodiment, the neutral engine output target value calculating section 47
The target engine output (torque) T _e ^* obtained by the target engine output calculation unit 63 is determined in accordance with the engine speed N _{e in the same} manner as in the above-described embodiment. A value limited to a value that can be eliminated may be used as the neutral engine output target value _TeH . In this case, the neutral engine output target value _TeH
Can be obtained simply and inexpensively, and the same operation and effect as in each of the above embodiments can be achieved economically.

In each embodiment, the case where the travel range is the D range has been described. However, even when the travel range is the reverse (R) range, the starting clutch 15 is engaged when the N → R select operation is performed. In the meantime,
Instead of the target engine output (torque) _Te ^* , the neutral engine output target value _TeH is used as the engine output (throttle opening).
It goes without saying that a similar effect can be obtained by contributing to control.

In each embodiment, the shift control for achieving the transmission target input rotation speed (target primary rotation speed) N _pri ^* is performed in the same manner as when the load is applied even when the vehicle is in the no-load state. Since the driving force is performed in such a manner as to realize the driving force T _S , the target gear ratio i ^* does not change at the time of D → N selection, and therefore, when returning to the D range by the N → D selection operation, there is no change in the gear ratio. And a smooth shift can be maintained.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram showing a power train of a vehicle equipped with a continuously variable transmission equipped with a driving force control device according to an embodiment of the present invention, together with a control system thereof.

FIG. 2 is an explanatory block diagram illustrating an example configuration of a starting clutch engagement determination circuit according to the embodiment;

FIG. 3 is an explanatory block diagram showing another example of the configuration of the starting clutch engagement determination circuit.

FIG. 4 is a functional block diagram of shift control and throttle opening control for driving force control executed by a controller in the embodiment shown in FIG. 1;

FIG. 5 is a functional block diagram of a shift control and a throttle opening control for driving force control according to the embodiment of the present invention.

FIG. 6 is a functional block diagram of a shift control and a throttle opening control for driving force control according to still another embodiment of the present invention.

FIG. 7 shows an equal fuel consumption line, an equal horsepower line, and a two-dimensional coordinate line defined by an engine speed axis and an engine output torque axis.
FIG. 4 is a characteristic diagram of an engine showing a minimum fuel consumption line.

FIG. 8 is a diagram when the minimum fuel consumption line is rewritten as a relationship diagram between the vehicle speed and the axle driving force for each gear ratio.

9 is a relationship diagram between the vehicle speed and the axle driving force, which is a diagram connecting the points at which the input rotation speeds become equal for each speed ratio on the diagram of FIG. 9;

FIG. 10 is a change characteristic diagram of a neutral engine output target value obtained by a neutral engine output target value calculation unit in the embodiment of FIGS. 4 and 5;

[Explanation of symbols]

 Reference Signs List 1 engine 2 continuously variable transmission 3 accelerator pedal 4 step motor 5 electronic control throttle valve 6 torque converter 7 primary pulley 8 secondary pulley 9 V belt 10 final drive gear set 11 differential gear device 12 hydraulic actuator 13 controller 14 accelerator pedal depression amount sensor 15 Start clutch (friction element) 16 Throttle opening sensor 17 Primary pulley rotation sensor 18 Secondary pulley rotation sensor 19 Vehicle speed sensor 20 Engine rotation sensor 21 Inhibitor switch 22 Start clutch engagement determination circuit 41 Request axle driving force calculation unit 42 Axle rotation speed calculation Section 43 Required horsepower calculation section 44 Transmission target input speed / target engine output calculation section 45 Target gear ratio calculation section 46 Changeover switch 47 Neutral engine output target value calculation section 48 Neutral range determination block 4 9 N → D select detection block 50 Start clutch non-engagement determination block 51 Target throttle opening calculation unit 61 Transmission target input speed calculation unit 62 Wheel drive system actual gear ratio calculation unit 63 Target engine output calculation unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideaki Watanabe Nissan Motor Co., Ltd., Nissan Motor Co., Ltd. (2) Nissan Motor Co., Ltd. (72) Inventor Keiichi Kawashima Nissan Motor Co., Ltd. Terms (Reference) 3D041 AA26 AA64 AC09 AC11 AC19 AC20 AD02 AD04 AD10 AD18 AD23 AD31 AD32 AD33 AD51 AE03 AE04 AE36 3G093 AA06 BA06 BA19 CA04 CB08 DA01 DA06 DB05 DB10 DB11 DB12 DB23 EA02 EA03 EA09 EB03 EC01 EC02 FA

Claims (7)

[Claims] 1. A vehicle equipped with a power train which is a combination of an engine whose output can be arbitrarily changed by a factor other than the operation of an accelerator pedal and a continuously variable transmission, wherein the vehicle has a driving state and running conditions which are different from each other. An optimum combination of a target engine speed and a target engine output for realizing the determined required axle driving force is determined, and the speed of the continuously variable transmission is controlled so that a transmission target input speed corresponding to the target engine speed is obtained. Along with
In the driving force control device for a vehicle, wherein the engine output is controlled to be the target engine output, when the continuously variable transmission is in a neutral state where power cannot be transmitted while the vehicle is traveling, the target engine output is replaced with the target engine output. A driving force control device for a vehicle, wherein a neutral engine output target value that does not cause engine speed to rise even in the neutral state contributes to the engine output control. 2. The driving force control device for a vehicle according to claim 1, wherein the neutral engine output target value is determined based on a predetermined characteristic from an accelerator pedal depression amount and an engine speed. 3. The characteristic according to claim 2, wherein the predetermined characteristic is such that the characteristic of the neutral engine output target value with respect to the amount of depression of the accelerator pedal is assigned so that the neutral engine output target value decreases as the engine speed increases. A driving force control device for a vehicle, comprising: 4. The driving force control device for a vehicle according to claim 1, wherein a value obtained by limiting the target engine output according to an engine speed is set as the neutral engine output target value. 5. The continuously variable transmission according to claim 1, wherein when the continuously variable transmission returns from a neutral state to a state in which power can be transmitted, a friction element for performing the return completes engagement. In the meantime, the driving force control device for a vehicle is configured such that the neutral engine output target value is continuously used for the engine output control. 6. The frictional element according to claim 5, wherein it is determined that the engagement of the friction element has been completed when a set time has elapsed after a command for changing the continuously variable transmission from a neutral state to a power transmission enabled state is issued. A driving force control device for a vehicle, comprising: 7. When the torque converter between the continuously variable transmission and the engine is in a lockup state in which an input / output element is directly connected between the input and output elements, the transmission input rotation speed becomes equal to the engine rotation speed. A driving force control device for a vehicle, characterized in that it is determined that the engagement of the friction elements has been completed when they match.