JPH09280081A - Driving force control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly accelerate a driving wheel while restraining racing of it in a device reducing the driving force of the driving wheel at being judged to be in racing by correcting the target driving force so that actual acceleration generated in a vehicle is a value corresponding to engine driving force. SOLUTION: When the slip ratio of a driving wheel 101 connected to an engine 100 exceeds a prescribed value, racing of the driving wheel 101 is judged by a slip judging means 103, and the driving force of the driving wheel 101 is reduced by a driving force restraining means 102. In a driving force control device preventing racing of the driving wheel 101 in this way, the driving force restraining means 102 is provided with a target driving force computing means 104 computing the target driving force of the driving wheel 101, an actual acceleration detecting means 105 detecting actual acceleration in the longitudinal direction generated in a vehicle, and an engine torque computing means 106 computing the driving force of the engine 100, and it is constituted to correct the target driving force by a correcting means 107 so that the acceleration becomes a value corresponding to the engine driving force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a driving force control device for preventing idling of drive wheels to ensure vehicle stability and drivability.

[0002]

2. Description of the Related Art As a driving force control device (or a traction control system) for preventing the driving wheels from idling at the time of acceleration to reduce the acceleration performance, there is a device for controlling the engine driving force or the braking force. Known from the past,
For example, Japanese Patent Laid-Open No. 4-55156 is known.

This is because when the drive wheels spin idle, the road surface friction coefficient μ is estimated from the vehicle acceleration obtained each time from the driven wheel speed, while after a predetermined time elapses, the road surface friction coefficient μ is calculated according to the averaged vehicle acceleration. The engine driving force and the like are estimated and reduced according to the road surface friction coefficient μ.

[0004]

However, in such a conventional driving force control device, the road surface friction coefficient μ
If the drive wheels run idle when the running resistance (or road surface resistance) is large, such as on a high uphill road, the drive force suppression control is started based on the driven wheel speed, and the drive force is reduced by the first control. If it becomes too large, the driving force cannot be smoothly restored, and because the running resistance is large, sufficient acceleration force cannot be obtained, and the acceleration performance of the vehicle deteriorates and the driver feels uncomfortable. There was a point.

Therefore, the present invention has been made in view of the above problems, and even if the drive wheels run idle when running resistance is large, the vehicle is smoothly accelerated while suppressing the drive wheels from spinning. It is an object of the present invention to provide a driving force control device that can be operated.

[0006]

A first aspect of the present invention is, as shown in FIG. 16, a drive wheel 101 connected to an engine 100.
And a slip determination means 103 for determining idling of the drive wheel 101 when the slip ratio of the drive wheel 101 with respect to the road surface exceeds a predetermined value, and the drive when the slip determination means 103 determines the idling of the drive wheel. In the vehicle driving force control device including the driving force suppressing means 102 that reduces the driving force of the wheels 101, the driving force suppressing means 102 calculates the target driving force TRQE of the driving wheels. And the actual longitudinal acceleration Xg that occurs in the vehicle
And an actual engine torque calculating means 10 for calculating the driving force TRQES of the engine.
6 and correction means 107 for correcting the target driving force TRQE so that the acceleration Xg becomes a value according to the engine driving force TRQES.

In the second aspect of the invention, as shown in FIG. 16, the correction means 107 includes an acceleration estimation means 108 for calculating an estimated acceleration on a flat road from the driving force of the engine 100. The target driving force TRQE is corrected based on the difference in the actual acceleration Xg.

Further, in a third aspect of the present invention, as shown in FIG. 16, the target driving force calculating means 104 includes feedback calculating means 110 for calculating a feedback term of the target driving force based on the speed of the driving wheels, and Feedforward calculation means 111 for calculating the feedforward term of the target driving force based on the actual acceleration, and addition means 112 for adding these feedback term and feedforward term.
Consists of

[0009]

Therefore, according to the first aspect of the invention, the drive force suppressing means reduces the drive force transmitted from the engine to the drive wheels to prevent the drive wheels from slipping when the slip ratio of the drive wheels with respect to the road surface exceeds a predetermined value. However, the driving force that is reduced at this time is the target driving force that is corrected to obtain the longitudinal acceleration that matches the actual engine driving force, so the driving force is temporarily suppressed to prevent idling. After that, the vehicle can be accelerated with an acceleration according to the actual engine torque,
For example, even if the drive wheels run idle when running resistance is high on an uphill road or the like, it is possible to accelerate the vehicle quickly after suppressing the idle running of the drive wheels.

According to a second aspect of the present invention, the target driving force is based on the difference between the estimated acceleration that would be obtained on the flat road from the driving force of the engine at that time and the actually generated acceleration, It is corrected so as to obtain the acceleration corresponding to the driving force.

According to a third aspect of the present invention, the target driving force calculation means targets the result obtained by adding the feedback term of the target driving force based on the speed of the driving wheels and the feedforward term of the target driving force based on the actual acceleration. The driving force is used as the driving force, and the correction means corrects the addition result to a value that gives an acceleration corresponding to the actual engine driving force. Therefore, the reduction of the driving force transmitted to the driving wheels becomes excessive. Can be prevented.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, the driving force control device comprises a TCS controller 1 composed of a microcomputer and the like, and a second throttle 10 as a driving force suppressing means controlled by the TCS controller 1 via an actuator 9. Indicate the case.

The engine 4 is connected to driving wheels via a transmission 6, and the engine 4 is controlled by the engine controller 2 in terms of fuel injection amount, ignition timing and the like according to operating conditions. Ne is sent from the engine controller 2 to the TCS controller 1.

The transmission 6 is of the FR type which is connected to the rear wheels RR and RL, and hereinafter, the left and right rear wheels RL and RR.
Is the driving wheel, and the left and right front wheels FL, FR are the driven wheels.

In the intake passage of the engine 4, a first throttle 8 that responds to an accelerator pedal 7 and a second throttle 10 that is controlled by a TCS controller 1 via an actuator 9 are arranged. The opening sensor 11 that detects the opening outputs the opening TVO of the first throttle 8 to the TCS controller 1.

The transmission 6 connected to the engine 4 is set by the transmission controller 3 to a gear ratio or a transmission ratio according to the operating state. The transmission controller 3 sets the set gear position GEAR or gear ratio iGEAR to TCS. It is sent to the controller 1.

The TCS controller 1 includes wheel speed sensors 12FR, 12 for detecting the rotational speed of each wheel or axle.
The detection signals of FL, 12RR, and 12RL are input, and the TCS controller 1 determines the wheel speeds VTF of these wheels.
Drive wheel R based on R, VTFL, VTRR, VTRL
When the idling of R and RL and the longitudinal acceleration Xg of the vehicle are detected, and the drive wheels RR and RL are idling, the second throttle 10 is controlled via the actuator 9 to adjust the torque (driving force) of the engine 4. By doing so, idling of the drive wheels RR and RL is suppressed.

An example of the control performed by the TCS controller 1 is shown in the flow charts of FIGS. 2 to 5, and the driving force control will be described in detail below with reference to these flow charts. Note that the control based on these flowcharts is executed every predetermined time.

First, in step S1, the outputs of the wheel speed sensors 12FR to 12RL are read, and in step S2.
At each wheel speed VTFR, VTFL, VTRR, VTR
Calculate L.

Then, in step S3, the engine speed N is changed from the engine controller 2 and the shift controller 3.
e, the gear position GEAR (or the gear ratio may be used) are read.

In step S4, the average speed VF of the driven wheels is
F is the wheel speed VTFR, VTFL of the left and right front wheels FR, FL
Then, in step S5, the average speed VRR of the driving wheels is similarly calculated as the wheel speed VT of the left and right rear wheels RR and RL.
Calculated from RR and VTRL.

Next, at step S6, the drive wheel speed threshold value VRRBS for detecting the idle rotation of the drive wheels is obtained by adding a predetermined constant β to the average driven wheel speed VFF corresponding to the current vehicle speed.

VRRBS = VFF + β In step S7, the target value VRRS of the drive wheel speed according to the current vehicle speed is obtained by adding a predetermined constant α to the driven wheel average speed VFF.

VRRS = VFF + α However, the predetermined value is set to α <β.

In step S8, the driven wheel average speed VF is set.
The current value VFF (n) of F and the value VF obtained in the previous processing
The difference between F (n-1) is multiplied by a predetermined conversion constant K to obtain the actual longitudinal acceleration (actual acceleration) Xg generated in the vehicle as follows.

Xg = {VFF (n) -VFF (n-1)} × K In the above steps S1 to S8, the drive wheel average speed VRR, the drive wheel speed threshold value VRRBS, the drive wheel speed target value VRRS and the longitudinal acceleration. After obtaining Xg, in step S9, the idling of the drive wheel is detected by determining whether or not the drive wheel average speed VRR exceeds the drive wheel speed threshold value VRRBS, and if the drive wheel is idling, step S9 is performed. In step S10, the driving force control flag FTCS (hereinafter, referred to as TCS control flag) for suppressing idling of the drive wheels RR and RL is set to 1.

On the other hand, when the drive wheel average speed VRR is less than the drive wheel speed threshold value VRRBS, the routine proceeds to step S11, where it is determined whether the TCS control flag FTCS is set, and if it is set, the driving force is set. Since the control is in progress, the process proceeds to step S12 in FIG. 3 and the TCS control flag FTCS is set.
If is not 1, the driving force control process ends.

Next, at step S12, the target drive torque TRQF required for accelerating the vehicle is calculated by the following equation based on the longitudinal acceleration Xg obtained at step S8.
The target drive torque TRQF constitutes a feedforward (hereinafter, F / F) term.

TRQF = Xg × INN where INN is a constant indicating the torque required per unit acceleration and is a characteristic value of the vehicle.

In step S13, the smaller one (select low) of the first throttle opening TVO and the second throttle opening THR read in step S3,
The actual engine torque TRQES is obtained from the engine speed Ne by the map F2 shown in FIG. The map of FIG. 6 is a map in which the actual engine torque TRQES is preset according to the select low of the first throttle opening TVO and the second throttle opening THR, and the engine speed Ne.

Then, in step S14, the estimated acceleration Xg 'that will be obtained on a flat road is obtained from the actual engine torque TRQES by the following equation.

Xg '= TRQES × INNG where INNG is the acceleration per unit weight,
This value is unique to the vehicle. In step S15, the difference DG between the actual acceleration Xg in step S8 and the estimated acceleration Xg 'in step S14 is calculated as follows.

DG = Xg'-Xg Then, in step S16, the correction coefficient τ of the F / F term is calculated by multiplying the acceleration difference DG by a predetermined coefficient K1.

Τ = K1 × DG Next, at step S17, the correction coefficient τ is added to the target drive torque TRQF of the F / F term obtained at step S12.
The target drive torque F / F term TRQF ′ is calculated by multiplying by.

After the feedforward term is calculated in this manner, the feedback (hereinafter, F / B) term is calculated in steps S18 to S23. The feedback control performed here is PID (proportional, integral, differential) control.

First, in step S18, the slip deviation GSLIP of the driving wheel is obtained from the difference between the driving wheel speed average value VRR and the driving wheel speed target value VRRS, and in step S19, the present value (n) of this slip deviation and the previous value. First slip deviation DGSL, which is the differential value of the slip deviation from (n-1)
The IP calculation is performed as follows.

GSLIP = VRR-VRRS DGSLIP = GSLIP _(n) -GSLIP _(n-1 ) Then, in step S20, the slip deviation GSL is obtained.
The change amount DTRQBI of the target drive torque F / B term integral term is obtained by multiplying IP by a predetermined integral gain KI.

DTRQBI = KI × GSLIP Next, in step S21 of FIG. 4, the F / B term integral term TR
The current value (n) of QBI is calculated from the previous value (n-1) plus this integral term change amount DTRQBI.

TRQBI _(n) = TRQBI _(n-1) + DTRQBI Thus, the integral term of the F / B term is obtained, and then step S
In 22, the proportional term and the derivative term T of the target drive torque F / B term
RQBP is calculated as follows from the slip deviation GSLIP and the slip first-order deviation DGSLIP obtained in steps S18 and S19.

TRQBP = KP × GSLIP + KD × DGSLIP where KP is a predetermined proportional gain and KD is a predetermined differential gain.

From the integral term TRQBI, proportional term and derivative term TRQBP of the F / B term, the target drive torque F / B term TR is obtained.
QB is calculated as follows.

TRQB = TRQBI + TRQBP In step S24, the target drive torque TRQE is calculated by adding the corrected target drive torques F / F term TRQF 'and F / B term TRQB.

TRQE = TRQF '+ TRQB Then, in step S25, the target drive torque TR
In order to obtain the engine torque TRQ corresponding to QE, the target drive torque TRQE obtained in step S24 is multiplied by a predetermined conversion constant NGEARG to calculate the target value of the engine torque TRQ. The conversion constant NGEARG is a value set according to the specifications of the vehicle.

TRQ = TRQ × ENGEARG Furthermore, in step S26, the engine torque TR
In order to realize Q, the second throttle opening degree THR is calculated from the engine torque TRQ and the engine speed Ne according to the following equation.

THR = F3 (TRQ, Ne) where F3 is the engine speed Ne as shown in FIG.
And the second throttle opening T depending on the engine torque TRQ
It is a map in which HR is preset.

Then, in step S27, it is determined whether or not the value of the second throttle opening THR is fully opened (8/8). If the second throttle opening THR is fully opened, the driving force suppression control is performed. To end the TCS in step S28.
The control flag FTCS is cleared to 0, and the integral term TRQBI of the target drive torque F / B term is cleared to 0 in step S29.

On the other hand, when the second throttle opening THR is less than full open, the process proceeds directly to step S30, the second throttle opening THR obtained in step S26 is output to drive the actuator 9, and the second Throttle 10
Is set to a predetermined opening degree THR, the driving force suppression control is performed so that the generated torque of the engine 4 matches the engine torque TRQ that is the target value.

By performing the above-described control every predetermined time, it becomes possible to surely accelerate the vehicle while suppressing the idling of the drive wheels at the time of starting and accelerating. One example is shown below.

Now, as shown in FIGS. 8 to 14, the case where the vehicle starts and accelerates on an uphill road having a high road friction coefficient μ will be described. From time t ₀ , the driver depresses the accelerator pedal 7 to full opening. The first throttle opening T
VO increases, and along with this, the engine speed Ne also rises and the drive wheel average speed VRR rises, while the driven wheel average speed VFF remains 0 and the drive wheels become idling.

Then, at time t ₁ , the drive wheel average speed VRR is
Exceeds the threshold value VRRBS, the above steps S9, 1
At 0, the TCS control flag FTCS is set to 1 and the driving force suppression control is started.

This driving force suppression control is carried out after step S12 in the target driving torque F / F term TRQF (step S1).
2) and the target drive torque F / B term TRQB (step S2
3) is obtained, and the F / F term TRQF is calculated as shown in FIG.
The correction result TRQF ′ of the F / F term is corrected by the correction coefficient τ (step S16) obtained from the difference DG between the estimated acceleration value Xg ′ that will be obtained in (1) and the actual acceleration Xg. The value is such that the acceleration Xg commensurate with the actual engine torque TRQES can be obtained. Then, the second throttle opening TH corresponding to the engine torque TRQ obtained from the corrected F / F term TRQF ′ and F / B term TRQB.
By the R, the drive torque is temporarily reduced in order to suppress the idling of the drive wheels, and then the engine torque TRQ can be quickly returned to smoothly accelerate the vehicle.

Here, a conceptual diagram of this control is as shown in FIG. 15, and the target drive torque F / B term TRQB obtained by PID control based on the drive wheel average speed VRR and the longitudinal acceleration Xg, and the above actual value. The target drive torque TRQE is calculated by adding the F / F term TRQF ′ corrected according to the correction coefficient τ corresponding to the engine torque TRQES, and the second throttle opening THR based on the target drive torque TRQE is obtained.
The driving force of the engine 4 is controlled in accordance with

On the other hand, in the conventional example, the above F /
The actual engine torque TRQ consisting of only the B and F / F terms
No correction is made by ES and longitudinal acceleration Xg.

Therefore, as shown by the alternate long and short dash line in FIG. 9, after the time t ₂ when the idling of the drive wheels converges, the target drive torque F
Since the / F term TRQF is suppressed, the second throttle opening THR remains almost closed, and the vehicle speed does not increase even though the driver depresses the accelerator pedal to accelerate. turn into. Where F /
It is possible to increase the gain of the B term, but when the gain becomes excessive, hunting occurs on a low μ road,
Drivability may be reduced.

On the other hand, in the present embodiment, the F / F term TRQF added to the F / B term TRQB as described above.
Is the acceleration Xg commensurate with the actual engine torque TRQES.
Since the target drive torque F / F term TRQF ′ is corrected by a correction coefficient τ such that the following equation is obtained, the target drive torque F / F term TRQF ′ rapidly rises after the time t ₂ when the idling of the drive wheels converges, as shown by the solid line in FIG.
Second throttle opening THR which is once closed at time t _1.
Is smoothly opened from time t2 onward in response to an increase in the F / F term TRQF ', and after suppressing idling of the drive wheels, the vehicle can be smoothly accelerated according to the driver's intention. Prevents a situation where the target driving torque does not rise smoothly and the acceleration performance deteriorates as in the conventional example,
When running resistance such as an uphill road or a road surface friction coefficient μ is large, it is possible to reliably accelerate the vehicle while suppressing idling of the driving wheels by suppressing excessive reduction of the driving force. Of course, since it is not necessary to increase the control gain of the F / B term as described above, hunting of control on a low μ road or the like with low running resistance is prevented, and a vehicle equipped with a driving force control device in all road surface conditions. It is possible to improve drivability and acceleration performance.

In the above embodiment, the means for suppressing the driving force is driven by the second actuator 9 through the actuator 9.
Although configured by the throttle 10, although not shown, the same operation and effect as above can be obtained by controlling the engine such as fuel cut and timing retard, and operating the brakes of the drive wheels RR and RL.

In the above embodiment, the F / F term TRQF is corrected by the correction coefficient τ according to the actual engine torque TRQES and the accelerations Xg, Xg '. Although not shown, the F / B term TRQB and The added value TRQE of the F / F term and the F / B term may be corrected by the correction coefficient τ.

[0059]

As described above, according to the first aspect of the present invention, the driving force suppressing means temporarily drives the driving force transmitted from the engine to the driving wheels when the slip ratio of the driving wheels to the road surface exceeds a predetermined value. Although the drive wheel slip is reduced to suppress the drive wheel slip, the drive force reduced at this time is the target drive force that is corrected to obtain the longitudinal acceleration commensurate with the actual engine torque. After temporarily suppressing the driving force, the vehicle can be accelerated at an acceleration according to the actual engine torque. For example, even if the driving wheels run idle when running resistance is large on an uphill road, etc. It becomes possible to accelerate the vehicle quickly while preventing idling, and prevent the situation where the target driving torque does not rise smoothly and the acceleration performance deteriorates as in the conventional example, and the driving force control device is provided. Car luck equipped It is possible to improve the sexual and acceleration performance.

In the second invention, the target driving force to be reduced is based on the difference between the estimated acceleration that would be obtained from the driving force of the engine at that time on a flat road and the acceleration actually generated. Since the acceleration is corrected so as to match the actual engine driving force, the vehicle can be smoothly accelerated according to the driver's intention after suppressing the idling of the driving wheels. As described above, it is possible to prevent a situation in which the target driving torque does not rise smoothly and the acceleration performance deteriorates, and it is possible to improve the drivability and the acceleration performance of the vehicle equipped with the driving force control device.

According to a third aspect of the present invention, the target driving force calculation means targets the result obtained by adding the feedback term of the target driving force based on the speed of the driving wheels and the feedforward term of the target driving force based on the actual acceleration. The driving force is used as a correction value, and the correction means corrects the addition result so as to obtain an acceleration value corresponding to the actual engine driving force. Therefore, even if the running resistance is large without changing the feedback gain. While suppressing the idling of the vehicle, while obtaining an acceleration corresponding to the actual engine driving force, and preventing hunting of the control on a low μ road where running resistance is small, the drivability of the vehicle equipped with the driving force control device The acceleration performance can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a driving force control device showing an embodiment of the present invention.

FIG. 2 is a flowchart showing an example of control similarly performed by the TCS controller, showing the first half.

FIG. 3 is a flowchart showing the first intermediate portion.

FIG. 4 is a flowchart showing a second intermediate portion.

FIG. 5 is a flowchart showing the latter half.

FIG. 6 is a map for calculating engine torque according to throttle opening and engine speed.

FIG. 7 is a second diagram according to engine speed and engine torque.
It is a calculation map of throttle opening THR.

FIG. 8 shows a state of driving force control at the time of starting, wheel speed,
5 is a graph showing the relationship between throttle opening, engine speed and time.

[Fig. 9] Similarly, actual longitudinal acceleration Xg, target drive torque feedback term TRQF, actual engine torque TRQES
6 is a graph showing the relationship between time and time.

FIG. 10 is an estimated acceleration Xg ′ on a flat road,
7 is a graph showing the relationship between the difference DG between the actual longitudinal acceleration and the estimated acceleration, the F / F term correction coefficient τ, and time.

FIG. 11 is a graph showing the relationship between slip deviation GSLIP, slip first floor deviation DGSLIP and time.

FIG. 12 is a graph showing the relationship between the target drive torque F / B term integration amount change amount DTRQBI, the F / B term integration term TRQBI, and time.

FIG. 13 is a graph showing a relationship between a target drive torque F / B term proportional term, a differential term TRQBP, a target drive torque F / B term, and time.

FIG. 14 is a graph showing a relationship between target drive torque TRQE, target engine torque TRQ and time.

FIG. 15 is a conceptual diagram of control.

FIG. 16 is a claim correspondence diagram corresponding to any one of the first to third inventions.

[Explanation of symbols]

1 TCS controller 2 engine controller 3 speed change controller 4 engine 6 transmission 7 accelerator pedal 8 first throttle 9 actuator 10 second throttle 11 throttle opening sensor 12FR, 12FL, 12RR, 12RL wheel speed sensor 100 engine 101 driving wheel 102 driving force Suppression means 103 Slip determination means 104 Target driving force calculation means 105 Actual acceleration detection means 106 Engine torque calculation means 107 Correction means 108 Acceleration estimation means 110 Feedback calculation means 111 Feedforward calculation means 112 Addition means

Claims (3)

[Claims] 1. A drive wheel connected to an engine, a slip determination means for determining idle rotation of the drive wheel when a slip ratio of the drive wheel with respect to a road surface exceeds a predetermined value, and the slip determination means for determining the drive wheel In a vehicle driving force control device including a driving force suppressing unit that reduces the driving force of the driving wheels when it is determined that the vehicle is idling, the driving force suppressing unit is a target drive that calculates a target driving force of the driving wheels. Force calculation means, actual acceleration detection means for detecting the actual longitudinal acceleration generated in the vehicle, actual engine torque calculation means for calculating the driving force of the engine, and so that the acceleration has a value according to the engine driving force. A driving force control device for a vehicle, comprising: a correction unit that corrects the target driving force. 2. The correcting means includes acceleration estimating means for calculating an estimated acceleration on a flat road from the driving force of the engine, and corrects the target driving force based on a difference between the estimated acceleration and the actual acceleration. The driving force control device for a vehicle according to claim 1, wherein 3. The target driving force calculating means calculates a feedback calculating means for calculating a feedback term of the target driving force on the basis of the speed of the driving wheels, and a feedforward term for the target driving force on the basis of the actual acceleration. 2. The vehicle driving force control apparatus according to claim 1, further comprising: a feedforward calculation unit that performs the above, and an addition unit that adds the feedback term and the feedforward term.