JP2005001485A - Driving force control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide target driving force in correspondence with a driving state while preventing deterioration of fuel consumption. <P>SOLUTION: This driving force control device is furnished with: an accelerator pedal operating position detection means to detect operating quantity of an accelerator pedal, a car speed detection means to detect speed of a vehicle; a target driving force computing part 21 to compute the target driving force in accordance with the operating quantity of the accelerator pedal and the car speed; and a driving force control means to control an engine and an automatic transmission so as to be this target driving force. The driving force control means is constituted to gradually lower the driving force by engine control while gradually increasing the driving force by gear ratio control after temporarily increasing the driving force by the engine control when the target driving force increases. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to driving force control for a vehicle including an internal combustion engine and a continuously variable transmission.
[0002]
[Prior art]
Conventionally, as a driving force control device used for a vehicle, as in JP 2000-297672 A, an engine and a transmission are controlled so that a target driving force corresponding to an accelerator depression amount, a vehicle speed, and a running resistance can be realized. The device is known.
[0003]
This is based on the accelerator depression amount APO and the vehicle speed VSP, and a reference target driving force equivalent to a flat road is set. When the running resistance increases, the corrected driving force is added and output as the target driving force for engine control. The vehicle driving force control apparatus includes a correction driving force addition unit that adds a correction driving force multiplied by a correction coefficient α to a reference target driving force to obtain a target driving force for shift control. The ratio obtained by dividing the correction driving force added to the target driving force for shift control by the correction driving force added to the target driving force for engine control changes according to the depression amount of the accelerator pedal.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-297672 [0005]
[Problems to be solved by the invention]
However, in the above-described conventional example, the correction driving force is multiplied by the correction coefficient α and added to the reference target driving force to obtain a target driving force for shift control. For example, when the driver approaches the gradient road with a constant accelerator depression amount, the driving force correction increases the driving force for the gradient resistance. The required driving force for increasing the gradient resistance is realized by the gear ratio and the engine torque, and the distribution of the gear ratio and the engine torque is determined according to the correction coefficient α. When the engine is controlled to an operating point with a good fuel economy rate due to demands on fuel efficiency before entering the ramp, that is, when operating at high load and low speed, the fuel increase range is required to increase the engine torque. However, there is a problem that fuel consumption deteriorates due to wasteful blowing of fuel due to an increase in fuel (the increased amount of fuel is for cooling the engine and does not affect the output).
[0006]
The ratio obtained by dividing the corrected driving force added to the target driving force for shift control by the corrected driving force added to the target driving force for engine control changes according to the amount of depression of the accelerator pedal. However, if the correction coefficient α is made variable according to the amount of depression of the accelerator pedal, the correction coefficient α is constant when traveling on a slope with a constant depression amount of the accelerator pedal. The fuel increase correction is always performed while the vehicle is traveling on the slope road, and there is a problem that the fuel consumption is remarkably deteriorated.
[0007]
Therefore, the present invention has been made in view of the above problems, and an object thereof is to realize a target driving force according to a driving state while preventing deterioration of fuel consumption.
[0008]
[Means for Solving the Problems]
The present invention relates to an accelerator pedal operation position detecting means for detecting a depression amount of an accelerator pedal, a vehicle speed detection means for detecting a vehicle speed, and a target for calculating a target driving force based on the depression amount and the vehicle speed of the accelerator pedal. In a vehicle driving force control device comprising driving force calculating means and driving force control means for controlling the engine and the automatic transmission so as to achieve this target driving force,
When the target driving force increases, the driving force control means temporarily increases the driving force by engine control, and then gradually decreases the driving force by engine control while gradually increasing the driving force by speed ratio control. If there is a driving force distribution correction means and the engine torque is in the region where fuel increase is required due to an increase in the target driving force, the engine torque is temporarily increased, and then the engine torque is gradually reduced and the gear ratio is changed. Is gradually increased to shift the engine torque to a region where fuel increase is not required.
[0009]
【The invention's effect】
Therefore, according to the present invention, when the target driving force increases, the fuel torque is temporarily increased to increase the engine torque, and then the gear ratio is gradually shifted to the Lo side and the engine torque is gradually reduced. While keeping the overall driving force constant, the distribution of driving force by gear ratio control and engine control can be gradually shifted to gear ratio control, preventing fuel deterioration and preventing the engine speed from rapidly increasing. Without giving a sense of incongruity, it is possible to improve both fuel efficiency and driving performance.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
[0011]
FIG. 1 shows a control unit for connecting an automatic transmission 8 having a torque converter to an engine 9 and controlling an output of the engine 9 and a gear ratio of the automatic transmission 8 so as to obtain an optimum driving force according to a traveling state. An example in which the present invention is applied to a vehicle having 2 is shown.
[0012]
The control unit 2 includes an accelerator depression amount APO (or throttle opening) from the accelerator position sensor 1, a select signal from a range selection lever or an inhibitor switch (not shown) for switching the shift range of the automatic transmission 8, wheel speed. The vehicle speed VSP detected by the sensor 11, the primary pulley rotation speed detected by the primary pulley rotation sensor 6, the secondary pulley rotation speed detected by the secondary pulley rotation sensor, etc. are input as driving states, and the target drive calculated based on these driving states The driving force of the vehicle is controlled by controlling the fuel injection amount of the engine 9 and the ignition timing, or by controlling the shift of the automatic transmission 8 so that the power can be obtained.
[0013]
For this reason, an electronically controlled throttle valve 30 that is opened and closed by the throttle actuator 3 is interposed in the intake passage of the engine 9, and the electronically controlled throttle is based on the throttle valve opening signal sent from the control unit 2. The opening degree of the valve 30 is controlled.
[0014]
The automatic transmission 8 is a continuously variable transmission capable of continuously changing the gear ratio in accordance with a gear change command from the control unit 2, and is obtained from the ratio between the primary pulley rotation speed and the secondary pulley rotation speed. The transmission mechanism is controlled so that the transmission gear ratio RATIO matches the command value from the control unit 2.
[0015]
Here, an example of the driving force control performed by the control unit 2 is shown in FIG.
[0016]
In FIG. 2, a reference target driving force TFDD which is a driving force of the vehicle on a flat road based on a map set in advance based on the accelerator depression amount APO from the accelerator position sensor 1 and the vehicle speed VSP detected by the wheel speed sensor 11. A reference target driving force calculating unit 21 for calculating the driving force, a corrected driving force calculating unit 22 for calculating a correcting driving force from a running resistance (acceleration resistance, climbing resistance, etc.) increased with respect to a preset reference value of the vehicle, and fuel increase An increased driving force speed ratio reflection ratio calculating unit 23 (distribution ratio correcting means) that calculates a reflection ratio αsft of the corrected driving force increased from the ratio to the speed ratio control, and a correction driving that multiplies the corrected driving force by the speed ratio reflecting ratio αsft. A force correction unit 26 and a gear ratio control request correction driving force calculation unit 27 (driving force) for obtaining a request correction driving force commanded to the gear ratio control by adding the multiplication result to the reference target driving force. The required driving force mMTFDD for gear ratio control is determined from the distribution correction means.
[0017]
In the engine control, the target engine torque calculation unit 24 calculates the target engine torque TTEP from the reference target driving force TFDD, the actual gear ratio, and the torque ratio of the torque converter, and the engine torque demand unit 25 calculates the necessary air from the target engine torque TTEP. After obtaining the amount, the target throttle opening degree TGTVO is calculated, and the throttle actuator 3 is driven at this target throttle opening degree TGTVO. Further, the engine torque demand unit 25 calculates the fuel injection amount necessary for realizing the target engine torque TTEP and controls the fuel injection valve (not shown).
[0018]
In the gear ratio control, the gear ratio control demand correction driving force mMTFDD obtained by the vehicle speed VSP and the gear ratio control request correction driving force calculation unit 27 based on a map preset by the gear ratio control accelerator opening calculation unit 28. The speed ratio control accelerator opening is obtained from the above, the speed ratio control accelerator opening is normalized by the normalizing section 29, and then the target input shaft rotational speed calculation section 41 is used to determine the vehicle speed VSP based on a preset map. The target input shaft rotational speed DsrREV is obtained from the speed ratio accelerator opening and the feedback control unit 42 determines the target speed ratio based on the target input shaft rotational speed DsrREV, and the actual speed ratio matches the target speed ratio. The hydraulic pressure control unit 5 is controlled as described above.
[0019]
Next, an example of the driving force control performed by the control unit 2 shown in FIG. 2 will be described in detail below with reference to the flowchart shown in FIG. Note that the flowchart of FIG. 3 is executed every predetermined time, for example, every 10 msec.
[0020]
First, in steps # 1 and # 2, the vehicle speed VSP and the accelerator depression amount APO are read from the wheel speed sensor 11 and the accelerator position sensor 1, and in step # 3, the map of the reference target driving force calculation unit 21 shown in FIG. Based on this, the reference target driving force TFDD is calculated.
[0021]
In step # 4, it is determined whether or not the driving force needs to be corrected. If correction is necessary, the process proceeds to step # 5. If not, the gear ratio reflection rate adjustment value αhos = 0 is set. After resetting, the process proceeds to step # 9 to perform gear ratio control. The determination of whether or not the driving force needs to be corrected may be made by determining that the driving force needs to be corrected when the vehicle speed VSP decreases when the accelerator depression amount APO is constant.
[0022]
In step # 5, a corrected driving force for the gradient resistance is calculated from the running resistance increased with respect to a preset reference value of the vehicle.
[0023]
Next, in step # 6 and subsequent steps, a distribution rate (reflection rate αsft) for transmission ratio control when the increased driving force determined in step # 5 is realized by the engine rotation speed and engine torque is determined.
[0024]
In step # 6, a reflection ratio (correction coefficient) α for the gear ratio control is determined for the driving force corresponding to the gradient obtained in step # 5. The transmission ratio reflection rate α is a value between 0 and 1, and is obtained in the same manner as in the conventional example.
[0025]
In step # 7, the gear ratio reflection rate α determined in step # 6 is determined depending on whether fuel increase is necessary.
[0026]
This request for increasing fuel is determined in step # 14.
[0027]
This determination is made based on the operating point of the engine (engine speed, engine torque). As shown in FIG. 5, it is determined whether the engine speed and engine torque are within a predetermined fuel increase range. It is determined by. If the fuel increase is necessary in this determination, the process proceeds to step # 16 to determine the gear ratio reflection rate adjustment value αhos. If the fuel increase is not required, the process proceeds to step # 15 and the gear ratio reflection rate adjustment value. Holds the value of αhos.
[0028]
In step # 16, when the fuel increase is necessary, the transmission ratio reflection rate adjustment value αhos is increased by a predetermined ratio (ratio) β,
αhos = αhos (previous value) + β
Asking. Note that β is an adapted constant ratio.
[0029]
In step # 7, the transmission ratio reflection ratio α is adjusted using the transmission ratio reflection ratio adjustment value αhos determined as described above. That is, if the gear ratio reflection rate after taking into account the fuel increase is αsft,
αsft = α + αhos
As a result, the gear ratio reflection rate αsft after taking into account the fuel increase is calculated.
[0030]
In step # 8, the corrected driving force is multiplied using the gear ratio reflection rate αsft after taking into account the fuel increase, and the required corrected driving force is obtained by adding the reference target driving force to the multiplication result (corrected driving force correcting unit). 26, transmission ratio control request correction driving force calculation unit 27).
[0031]
In step # 9, the accelerator opening for gear ratio control is obtained based on the required corrected driving force, and the target gear ratio is determined from the target input shaft rotational speed DsrREV by the target input shaft rotational speed calculator 41 in FIG. The hydraulic control unit 5 of the automatic transmission 8 is driven by the unit 42.
[0032]
Next, in steps # 10 and # 11, the actual gear ratio is calculated from the primary pulley rotation speed and the secondary pulley rotation speed and the torque ratio of the torque converter is obtained. In step # 12, the target engine is calculated from the actual gear ratio and the torque ratio. Torque is obtained (target engine torque calculator 24).
[0033]
In step # 13, the required air amount is obtained from the target engine torque TTEP, the target throttle opening TGTVO is calculated, the throttle actuator 3 is driven at the target throttle opening TGTVO, and the target engine torque TTEP is calculated. The fuel injection amount necessary for the realization is calculated to control the fuel injection valve (engine torque demand unit 25).
[0034]
By the above control, the torque generated by the fuel increase in the conventional technology can be replaced with the gear ratio control, thereby preventing the deterioration of the fuel consumption due to the fuel increase. In particular, the correction drive force is generated by entering the gradient road. When shifting, the gear ratio is controlled so as to smoothly shift by a predetermined ratio β when shifting from the driving force increasing state due to engine torque to the driving force increasing state due to gear ratio control. By suppressing the sudden increase in the engine speed and preventing the driver from feeling uncomfortable, the smooth transition from the torque control state to the gear ratio control state allows the driver to feel uncomfortable when entering the hill and increase fuel consumption. It is possible to achieve both improvement of deterioration.
[0035]
That is, when entering the slope road (uphill road), the relationship among the accelerator depression amount APO, the target driving force TFDD, the engine torque, the fuel increase rate, and the engine rotation speed is as shown in FIG. In FIG. 4, the present invention is indicated by a broken line, and a conventional example is indicated by a solid line.
[0036]
When the accelerator is depressed in a constant driving state and the vehicle approaches the uphill road at time T1, the target driving force increases by the amount of the gradient due to the increase in running resistance. In the conventional example, in order to compensate for the increase in the target driving force by increasing the engine torque, the engine torque enters the area where the fuel increase is required (the hatched area in the figure), while the speed ratio is constant. Therefore, as described in the above problem, the fuel consumption is remarkably deteriorated.
[0037]
On the other hand, according to the present invention, when the vehicle approaches the uphill road at time T1, the target driving force increases by the gradient due to the increase in running resistance. First, the increase in the target driving force due to the increase in engine torque is achieved. In order to compensate for this, the engine torque (driving force by engine control) temporarily enters the region where the fuel increase is necessary (the shaded area in the figure) and is increased, but the gear ratio reflection rate αsf after taking into account the fuel increase is Since the speed ratio increases by a predetermined ratio β, the speed ratio gradually shifts to the Lo side (large side) with the passage of time, and the driving force by the speed ratio control gradually increases. Along with this, the engine torque gradually decreases, and at time T2, the engine torque falls below the region where fuel increase is required.
[0038]
As a result, when the target driving force increases, the engine torque is temporarily increased to increase the engine torque, and then the gear ratio is gradually shifted to the Lo side and the engine torque is gradually reduced. While keeping the driving force constant, the distribution of the driving force by the gear ratio control and the engine control can be gradually shifted to the gear ratio control, preventing the deterioration of fuel consumption and preventing the engine speed from rapidly increasing, giving the driver a sense of incongruity Therefore, it is possible to achieve both improved fuel efficiency and improved drivability.
[0039]
Note that the increase in the gear ratio to the Lo side may be performed until the engine torque deviates from the fuel increase requirement region.
[0040]
Further, the reduction of the engine torque may be set so as to correspond to a value obtained by multiplying the target driving force by (1−αsft).
[0041]
Further, it is determined whether or not the engine torque enters the region where the fuel increase is required due to the increase of the target driving force, and when it is determined that the engine torque enters the fuel increase region, the correction is made so that the engine torque is gradually reduced. In addition, by performing distribution ratio correction that gradually increases the gear ratio, when the target driving force increases due to entering an uphill road, the gear ratio is gradually shifted to the Lo side and the engine torque is gradually reduced. As a result, while maintaining the overall driving force constant, the distribution of the driving force by the gear ratio control and the engine control can be gradually shifted to the gear ratio control, preventing deterioration of fuel consumption and suppressing rapid gear shifting. Therefore, the rapid increase in engine rotation speed can be prevented without causing the driver to feel uncomfortable, and both improved fuel efficiency and improved drivability can be achieved.
[0042]
Further, if the engine torque is in the region where the fuel increase is required due to the increase in the target driving force, the engine torque is temporarily increased, and then the engine torque is gradually decreased and the gear ratio is gradually increased. By shifting the torque to a region where fuel increase is not required, when the target driving force increases due to entering the uphill road, the fuel torque is temporarily increased to increase the engine torque to prevent the vehicle speed VSP from decreasing. Later, by gradually shifting the gear ratio to the Lo side and gradually reducing the engine torque, the gear ratio control and the distribution of the driving force by the engine control are gradually controlled while keeping the overall driving force constant. To prevent the deterioration of fuel efficiency and prevent sudden increase in engine speed without causing driver discomfort and improving fuel efficiency. We can achieve both an improvement in drivability.
[0043]
In addition, the target driving force realized by engine control and the target driving force realized by gear ratio control are calculated, and when the target driving force increases, a correction coefficient that gradually increases as time elapses is changed. Multiplying the target driving force realized in step 1 to increase the driving force realized by gear ratio control, while increasing the driving force realized by engine control by multiplying the target driving force realized by engine control with a correction coefficient that gradually decreases over time By reducing the driving force to be used, when the target driving force increases due to entering the uphill road, etc., the gear ratio is gradually shifted to the Lo side and the engine torque is gradually reduced with the passage of time. , While maintaining the overall driving force constant, the distribution of the driving force by the gear ratio control and engine control can be gradually shifted to the gear ratio control, preventing deterioration of fuel consumption and rapid gear shifting Preventing rapid increase in engine speed by suppressing without discomfort to the driver, we can achieve both an improvement in drivability and improve fuel efficiency.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a vehicle for controlling a driving force according to an embodiment of the present invention.
FIG. 2 is a block diagram showing an example of driving force control performed by a control unit.
FIG. 3 is a flowchart similarly showing an example of driving force control.
FIG. 4 is a graph showing a change in each value due to an increase in gradient, in which a broken line indicates the case of the present invention, and a solid line indicates a case of the conventional example. The relationship between fuel increase rate and engine speed and time is shown.
FIG. 5 is a map showing a relationship between engine rotation speed and engine torque.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Accelerator position sensor 2 Control unit 3 Throttle actuator 5 Hydraulic control part 6 Primary pulley rotation sensor 7 Secondary pulley rotation sensor 8 Automatic transmission 9 Engine 10 Crank angle sensor 11 Wheel speed sensor 21 Reference target driving force setting part 27 Gear ratio control request Driving force calculation unit 22 Correction driving force calculation unit 23 Increased driving force gear ratio reflection rate calculation unit 24 Target engine torque calculation unit 25 Engine torque demand unit 26 Correction driving force correction unit 41 Target gear ratio setting unit 42 Gear ratio feedback control unit

Claims (4)

An accelerator pedal operation position detecting means for detecting the amount of depression of the accelerator pedal;
Vehicle speed detection means for detecting the speed of the vehicle;
A target driving force calculating means for calculating a target driving force based on the depression amount of the accelerator pedal and the vehicle speed;
In the vehicle driving force control device including the driving force control means for controlling the engine and the automatic transmission to achieve the target driving force,
When the target driving force increases, the driving force control means temporarily increases the driving force by engine control, and then gradually decreases the driving force by engine control while gradually increasing the driving force by speed ratio control. A driving force control apparatus for a vehicle comprising driving force distribution correcting means. The driving force distribution correcting means includes an engine operating point determining means for determining whether or not the engine torque enters an area where fuel increase is required due to an increase in the target driving force;
2. A distribution ratio correction unit that corrects the engine torque to be gradually reduced when it is determined that the engine torque enters a fuel increase region, and gradually increases a gear ratio. The driving force control device for a vehicle according to claim 1. If the engine torque is in a region where the fuel increase is required due to an increase in the target driving force, the distribution ratio correcting means temporarily increases the engine torque and then gradually decreases the engine torque and gradually increases the speed ratio. The driving force control apparatus for a vehicle according to claim 2, wherein the engine torque is increased and the engine torque is shifted to a region where fuel increase is not required. The target driving force calculating means calculates a target driving force realized by engine control and a target driving force realized by gear ratio control, respectively.
When the target driving force increases, the driving force distribution correcting unit multiplies the target driving force realized by the gear ratio control by a correction coefficient that gradually increases with the passage of time, and the driving force realized by the gear ratio control. The driving force realized by the engine control is reduced by multiplying the target driving force realized by the engine control by a correction coefficient that gradually decreases as time elapses. 4. The driving force control apparatus for a vehicle according to any one of 3 above.

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