JPH0382640A - Vehicle traction control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a traction control device for a vehicle that prevents wheel drive slip (wheel spin).

(Prior Art) This type of device generally prevents wheel drive slip by braking the drive wheels or reducing the force transmitted to the drive wheels, as shown in Japanese Patent Application Laid-Open No. 61-85248. .

(Problem to be Solved by the Invention) Conventionally, when determining drive slip, it is common to determine that drive slip has occurred when the slip rate or amount of slip of the drive wheels exceeds a certain set value. Therefore, the sensitivity of the traction control was fixed. However, the optimum sensitivity differs depending on the driving condition, and the traction control sensitivity should be relatively dull when driving straight ahead or turning with large lateral acceleration (high friction road), and when driving with small lateral acceleration (low friction road) excluding straight driving. It is better to make the traction control sensitivity relatively sharp.

However, if the traction control sensitivity is fixed as in the past, it will be too sensitive to the above requirements when driving straight ahead or when turning with high lateral acceleration, or it will be too sluggish during turning when driving with small lateral acceleration other than straight driving. In the former case, the Traxicon control starts too early, resulting in poor acceleration while driving straight ahead, and a tendency to understeer during turns with high lateral acceleration, resulting in a lack of sharpness. In the latter case,
The start of traction control is too late, resulting in a decrease in turning stability due to wheel spin during turning with small lateral accelerations.

This invention improves traction control sensitivity! The first purpose is to eliminate the above-mentioned disadvantages by making it possible to change the speed according to the acceleration.

On the other hand, when performing power drift driving while driving with large lateral acceleration (driving that changes the direction of the vehicle while sliding the drive wheels by depressing the accelerator pedal), the sensitivity control described above will cause the drive wheels to shift immediately after shifting to power drift driving. Since the lateral acceleration decreases due to sideslip, the traction control sensitivity is switched to a sharp one suitable for this small lateral acceleration turning, and traction control is executed, making the intended power drift driving impossible.

A second object of the present invention is to solve this problem as well.

(Means for Solving the Problems) For the first purpose, the traction control device of the present invention, as shown in concept in FIG. In a vehicle equipped with a traction control means that prevents drive slip by at least one of reducing the transmission force of The sensor is equipped with a sensitivity changing means.

Further, for the second purpose, the present invention maintains the sensitivity of the traction control means corresponding to the large lateral acceleration state at the beginning of switching the sensitivity changing means from the large lateral acceleration state to the small lateral acceleration state. Configure it like this.

(Function) When the wheel drive force becomes excessive compared to the road surface friction force, the wheels generate drive slip. When a drive slip occurs, the traction control means suppresses the drive slip by at least one of braking the drive wheels and reducing the force transmitted to the drive wheels.

The sensitivity changing means changes the sensitivity of the traction control means in accordance with the lateral acceleration of the vehicle detected by the lateral G sensor. Therefore, as is usually preferred, this sensitivity should be relatively dull when driving straight ahead or when turning with large lateral accelerations (high friction roads), and when driving with small lateral accelerations (low friction roads) other than when driving straight ahead.
It can be changed depending on the driving condition, such as making it relatively sharp when turning. Therefore, it is possible to delay the start of traction control when driving straight ahead or when turning with large lateral acceleration, to prevent poor acceleration during straight driving or lack of sharpness during turning with large lateral acceleration. During cornering, traction control can be started earlier to prevent a decline in cornering stability.

Further, in the configuration of claim 2, the sensitivity changing means leaves the traction control sensitivity as the sensitivity corresponding to the large lateral acceleration turning driving at the beginning of switching from the large lateral acceleration turning driving to the small lateral acceleration turning driving, so that the power is changed. Even if the lateral acceleration temporarily decreases due to the drive wheels slipping due to drifting, power drifting can continue.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a system diagram showing an embodiment of the traction control device of the present invention. IL and IR are the left and right driven wheels (
For example, left and right front wheels), 2L, and 2R are left and right drive wheels (
For example, left and right rear wheels). The vehicle has 2L wheels.

2R is driven by an engine (not shown) and runs 01. It is assumed that the output of the engine is controlled by a throttle valve 4.

The throttle valve 4 is opened and closed by a step motor 5.
The number of steps (opening degree of the throttle valve 4) is basically controlled by the control circuit 7 so as to correspond to the amount of depression of the accelerator pedal 6 by the driver except during traction control.

For this purpose, a signal TI from a throttle sensor 8 that detects the opening degree of the throttle valve 4, that is, the number of steps of the motor 5, is fed back to the control circuit 7, and an accelerator sensor 9 that detects the depression ItAcc of the accelerator pedal 6.
The signal from the controller is input manually to the control circuit 7.

The control circuit 7 includes a microcomputer 10 and an A/D converter 11 and a P/D converter 11 on its input side.
A V converter 12 is provided, and a drive circuit 13 for the step motor 5 and a D/A converter I4 are provided on the output side. The A/D converter 11 receives the throttle opening signal T.
l (and the accelerator signal 1'lcc is analog-to-digital converted and inputted to the microcomputer 10,
The frequency-voltage converted voltage signal is converted into a digital signal by the F/V converter 12, and the microcomputer 1
Enter 0.

Each wheel IL, 11? , 2L, and 2R are brake master cylinders 21 that correspond to the depression force of the brake pedal 20.
The wheel cylinder 22 is actuated by hydraulic pressure P from
L22R, 23L, and 23R are provided, and the corresponding wheels are individually braked by the operation of these wheel cylinders. Therefore, the brake fluid pressure systems of the driving wheels 2L and 2R each include a fluid pressure control valve 24 for traction control.
Insert L and 24R. These hydraulic pressure control valves have the same specifications and the same structure, and the spool 25 is elastically supported by a spring 26 at the leftmost position shown in the figure, and the plunger 27 is elastically supported by a spring 28 at the leftmost position shown in the figure. .

Each of the hydraulic pressure control valves 24L and 24R outputs the hydraulic pressure P to the artificial boat 29 on the master cylinder side directly to the corresponding wheel cylinder from the outlet port 1-30 on the wheel cylinder side in the normal state shown, and controls the spool 25. When moving to the right, the plunger 27 isolates the boat 29 and 30 and increases the hydraulic pressure to the wheel cylinder, and when the spool 25 stops moving to the right, the increased hydraulic pressure in the wheel cylinder is maintained.

The right movement of the spool 25 and its stop are controlled by the pressure inside the chamber 31, and this pressure is controlled by the solenoid valves 40L, respectively.

Controlled individually by 40R. These solenoid valves are also similar, and when the solenoid 41 is OFF, it is in the boat-to-boat connection position shown in (A), connecting the chamber 31 to the drain circuit 42 and is cut off from the accumulator 43, and when the solenoid 41 is ON with a small current ( When the solenoid 41 is turned on due to a large current, the chamber 31 is in the port-to-port connection position shown in B) and the chamber 31 is drained. It is assumed that it is cut off from the circuit 42 and communicated with the accumulator 43.

When the solenoid valves 40L and 40R are in the (A) position, the chamber 31 is in a no-pressure state, the spool 25 is in the illustrated position, and the solenoid valve 40L is turned on.
At the position (C) of 40R, the chamber 31 is supplied with the constant value Pc of the accumulator 43, causing the spool 25 to move to the right in the figure, and at the position (B) of the solenoid valves 40L and 40R, the chamber 31 stops supplying and discharging pressure. to hold the spool 25 in its current rightward position.

The accumulator 43 stores hydraulic pressure from a pump 45 driven by a motor 44 via a check valve 46, and when the accumulated pressure value of the accumulator 43 reaches a constant value PC, a pressure switch 47 detects this and turns it off. It is assumed that upon receiving the signal, the control circuit 7 stops the motor 44 (pump 45). For this purpose, the signal from the pressure switch 47 is input to the microcomputer 10, and the motor control signal from the microcomputer 10 is converted into an analog signal by the D/A converter 14 and supplied to the motor 44.

The solenoid 41 of the solenoid valves 40L and 40R is also controlled by the microcomputer 10 on the drive side? 3'ff L, the control signal therefor is converted into an analog signal by the D/A converter 14 and supplied to the solenoid 1-41.

Wheel rotation sensors 50L, 50R, 511, and 51R are provided in association with each wheel IL, IR, 2L, and 2R, respectively, and these sensors detect the wheel speed VFL+VFR1 of the corresponding wheel.
Pulse signals of frequencies corresponding to νRLI V and 1R are generated, and these pulse signals are supplied to the F/V converter 12. The F/V converter 12 converts each pulse signal into a voltage corresponding to its frequency (wheel rotation speed) and inputs it to the A/D converter 11. The A/D converter 11 converts these voltages into digital signals. input to the microcomputer 10. The A/D converter 11 further converts a signal from a lateral G sensor 52 that detects the lateral acceleration G of the vehicle into a digital signal and inputs it to the microcomputer 10 .

In addition, the hydraulic pressure of the driving wheel cylinders 23L and 23R,
That is, pressure sensors 60L and 60R are provided to detect the drive wheel brake fluid pressures PBL+PBR, respectively, and the signals from these are converted into digital signals by the A/D converter 11 and input to the microcomputer 10.

The microcomputer 10 executes the control programs shown in FIGS. 3 to 6 based on various human input information to control the normal opening of the throttle valve 4 and the opening for traction control, and also controls the opening of the solenoid valve solenoid 41. position control, that is, braking control for traction control of the driving wheels, and further controls the position of the pump motor 44 (extraction pump 4).
5) performs drive control. 3 to 5 are main routines in which an operating system (not shown) performs regular interrupt processing at fixed intervals ΔT (for example, ΔT=10 m5ec) after engine startup, and FIG. 6 shows interrupt processing determined within this main routine. OCI (Output compare 1nter
rupt) indicates interrupt processing.

In FIG. 3, first, in steps 101 and 102, the first
Only for the second processing, the microcomputer 10 uses the built-in RA.
Initialize M, etc. The next step 103 is wheel speed VFR+VFL+v+tt,
The VRII is read, and based on these, in step 104, the slip ratios S, S, of the left and right drive wheels 2L and 2R are set to SL.
= (VRL VFL)/VFL, SN = (
VIIRVFR) / Tod: After obtaining from Step 105, the slip rate change speed of the left and right driving wheels 2L and 2R ゑL = SL 5L-1 (However, S, -1 is the previous left driving wheel slip rate) SR5R-1 (However, 5l
l-1 is the previous right drive wheel slip rate).

In step 106, the smaller of the left and right drive wheel slip ratios 5LSR is selected as the low slip ratio S. , set the larger one to the select high slip rate 5lnaX. Next, in step 107, the smaller value S of the select low slip rate and the select high slip rate is determined.
Slip rate weighting that emphasizes m1n with a ratio of K (for example, 0.6-0.9) is based on the average value Sav as S, v-KXSf
fii, +(1-K) x 5m5x, and its rate of change Sav is determined by S, v=S-vS-v-1 (5aV-+ is the average value of the previous slip rate weighting).

In step 148, the table data engine output control lower set value S1 corresponding to FIG. The upper setting value S2 for engine output control is determined by the calculation. In the next step 149, the slip ratio setting value correction coefficient ε is amplified from the lateral acceleration G based on the table data corresponding to FIG. This coefficient ε is calculated in step 15.
As shown in 0, the correction setting values (indicated by the same symbols S, , S2) to be set are determined by multiplying the setting values Sl+s2 by each of the above setting values S. , S2 are respectively shown in Fig. 7, and as will be described later, they are set values for determining the occurrence of wheel drive slip, so the ε〉1 traction control sensitivity is dulled and reduced. 1 corresponds to sharpening the traction control sensitivity. By the way, according to the table data in Figure 16, in light of the above requirements, if the lateral acceleration G is less than 0.4 g, the traction control sensitivity should be set to sharp <<, G≧0.
．． If it is 4 g, the traction control sensitivity will be decreased.

In step 151, the throttle opening degree Tl+ is changed to the depression amount Ace of the accelerator pedal 6 based on the above-mentioned slip ratio average value Siv and its rate of change Sav, based on the throttle opening control range data as shown in FIG. 7, which is suitable for traction control. The direction should be returned (increased) to the value corresponding to the non-control range, or the throttle valve 4 should be quickly closed (suddenly decreasing throttle opening Tl+) or slowly closing (slowly decreasing throttle opening Tll) the wheel 2L. , Determine whether the 2R drive slip should be applied in the rapid closing region or the gradual closing region, or in the holding region where the throttle opening TH should be kept unchanged. The result of this determination is processed in step 152.
~154, and in the non-control area, go to step 201, in the slow closing area, go to step 301, and in the sudden closing area, go to step 351
In the hold area, the control proceeds to step 401, respectively.

In the non-control area, in steps 201 to 206, the map up counter MA is cleared in step 204 and incremented (stepped) in step 203 or 205.
Each time P(IPC indicates a fixed recovery time TR, that is, every TR time, the throttle opening map MAP is determined as the previous map (M^PO)-, 1 in step 206, and then the control proceeds to step 401. MAP is number 8
As shown in the figure, 20 types are set from the 0th page to the 19th page, and the above map up means a command to increase the throttle valve opening degree to a value corresponding to the accelerator pedal depression IACc.

When the control proceeds to step 301 because the throttle is in the slow closing range, first in this step it is checked which throttle control range was used last time. If it was in the uncontrolled area last time, perform the following process 1.
Do it only once. That is, in step 302, the above map up counter MAPUPC is cleared, and in the next step 303
．． In 304, it is determined whether the left or right pressure reduction flag and the left or right sudden pressure reduction flag are both 0. As described later, these flags become O when the brake fluid pressure for traction control of the corresponding left and right drive wheels 2L and 2R is suddenly reduced for a predetermined period of time or more, and becomes O when the pressure is suddenly reduced for a predetermined period of time or more, and at least one of the drive wheels is in a sudden pressure reduction state. If so, step 305
In this case, the map drop number MAPDN is set to 1, and in other cases, l'DN=2 is set to the gate in step 306.

In step 307, the larger of the previous map gate ΔPo and the map number PMAR from a predetermined time ago stored in memory as described later (the one with the smaller throttle opening) is set as PMAX in the select high temperature gate. pump 30
Step 3 of this select high map MAPMAX with 8
The current map is set by lowering the map by the number MAPDN determined in step 05 or 306 (MAPMAX + MAPDN), and a command is given to gently close or close the throttle opening. In addition, in steps 309 and 310, if the above MAP is less than the initial map MAPIN1 obtained when the non-control area first changes to the slow closing area, it means that an increase in throttle opening is commanded, and the intention of slow closing is not met. Since it is contrary to MAP=
Let it be MAPINI.

If it is determined in step 301 that the previous time was in the slow closing region or rapid closing region, the control proceeds directly to step 401, and if the previous time was in the holding region, in step 311 the previous map MA
This time MAP is the one where PO is dropped by 1.
After issuing a command to reduce the throttle opening as follows, the control proceeds to step 401.

If the control proceeds to step 351 due to a sudden closing range, the previous throttle opening control range is first checked here. If it was in the non-control area last time, the same processing as steps 302 to 310 is performed in steps 352 to 360, and in step 362, 2 is added to the map obtained by this processing to command a sudden decrease in the throttle opening. Control step 4
Proceed to 01. If it is determined in step 351 that the area was in the sudden closing area from the previous time, the control proceeds directly to step 401, and if it was in the gradual closing area or holding area last time, step 36
After performing the same processing as in step 311 in step 1, control proceeds to step 401.

If the control proceeds to step 401 because of the holding area (same after processing for the non-control area, slow pressure increase area, and rapid pressure increase area), in steps 401 to 404, the set map number is in the range of O to 19 shown in FIG. Set the outer MAP value to the nearest limit value 0 or 19. In the next steps 405 and 406, the brake fluid pressure increase state of the left and right drive wheels 2L and 2R, in which both the left and right pressure reduction flags are not O, and both the left and right sudden pressure reduction flags are not O, is checked. If the pressure is not increased (if the pressure is decreased), in step 407, the throttle slow/sudden closing control (
If the pressure is increased, in step 408, the map of a predetermined time THI longer than T is set as PMAP. In the next step 409, the current map MAP is stored as the previous map MAP O in preparation for the next time.

After the above processing shown in FIG. 3, the control proceeds to step 5 in FIG.
The program proceeds to step 02, where the accelerator pedal depression fiAcc is read. In the next step 503, the target step number 5TEP of the step motor 5 corresponding to the accelerator pedal depression amount Acc is determined by searching the map based on the opening characteristic map corresponding to the map MAP obtained as described above.

In step 504, the target opening step number 5T of the throttle valve 4 determined in step 503 is determined.
The deviation Dir between EP and the actual opening step number TH is calculated by Dif=STEP-Tll. Further, in steps 505 and 506, the speed of the step motor 5 is determined based on the above deviation Dir, forward rotation/reverse rotation/holding is determined, and furthermore, 0(, I interrupt period is set, a flag regarding the motor rotation direction is set, etc. .

In steps 550 to 554, the left driving wheel brake fluid pressure P
Determine whether BL is greater than or equal to the set value P□, or less than this and the minute set value 14, or less than PL, and set the low pressure flag to 1 when PBL≧P□, and set the low pressure flag when PL≦PAIL<PH. The flag is reset to 0, and the no-control flag when PBL<PL is reset to 0.

In step 599, the lower setting value Sz of the slip ratio for driving wheel braking (common to the left and right driving wheels) required for traction control is looked up based on the table data corresponding to FIG. 15 from the front two wheels average speed VF, and at the same time, the traction The driving wheel braking slip ratio upper set value SI2 necessary for control is determined by the calculation. Then, in the next step 600, each of the SII+ 812 is sent to step 149 in FIG.
is multiplied by the correction coefficient ε, and the correction setting value (same sign SIl+31
(indicated by □) and set it.

Thereafter, in steps 601 to 693, the left drive shaft is braked and released for traction control at an appropriate speed as follows. In step 601, based on the table data corresponding to FIG. 9, the slip ratio average value SaW and its rate of change Smv are used to determine whether the left driving wheel brake fluid pressure should be rapidly increased, gradually increased, or held, and whether the pressure should be gradually decreased. Determine whether the area should be rapidly depressurized or not. The table data in Fig. 9 shows the control mode of the left drive wheel brake fluid pressure suitable for traction control, and the slip ratio average value S, v (Sz, Szz are the area boundary values determined above) and its rate of change 5-v. (S21.0. Szz is a fixed area boundary value) should be increased at a higher speed, and the lower the slip ratio average value SaV and its rate of change SmV, the faster the pressure should be reduced. Note that FIG. 9 also shows the right drive wheel brake fluid pressure control mode, which will be described later. Therefore, the brake 1711 for traction control of the left and right drive wheels is a common control based on a common slip ratio average value Siv and its rate of change Saw. Become.

The above area determination result is determined in steps 602 to 605, and the process branches to the corresponding steps in FIG.

That is, if it is a rapidly increasing pressure area, go to step 611, if it is a slow pressure increasing area, go to step 631, and if it is a holding pressure area, go to step 65.
If the pressure reduction area is <1, the control proceeds to step 661, and if it is a sudden pressure reduction area, the control proceeds to step 681.

If step 611 is selected due to the increase in pressure area,
First of all, don't get involved in the sudden pressure increase! decompression counter,
Clear the rapid pressure reduction counter, slow pressure increase counter, pressure hold taunter, and promotion counter, respectively.

In the next step 612, the previous area is checked, and if it was the previous decompression area, the loop passing through step 614 is 1
If the pressure was increased or maintained in the pressure area last time, a loop passing through step 618 is executed.

In the former loop, first, in steps 614 and 613, it is checked whether the pressure reduction flag and the 2N pressure flag are O, that is, whether rapid pressure reduction has been performed for a predetermined time or more.

If the previous pressure was in a sudden pressure reduction state, it is necessary to perform an initial pressure increase faster than the sudden pressure increase to eliminate response delay, so the initial pressure increase counter is incremented in step 615. Thereafter, in step 691, the solenoid valve 40L is set to the C position. At this solenoid valve position, the hydraulic control valve 24L is connected to the spool 25.
According to the second row in Figure 2, the left drive wheel brake fluid pressure is increased and the left drive shaft is braked for traction control.

Therefore, if the pressure reduction flag is not 0 or the sudden pressure reduction flag is not -0, the above initial pressure increase is not necessary, so step 616
Increment the rapid pressure counter in step 691.
Execute.

Thereafter, step 612 selects step 618, in which the pressure reduction flag is set to 1.

In steps 619 and 620, it is checked whether the above-mentioned initial pressure increase counter is 4 or O, but if step 615 has been executed, the path of steps 619, 620, and 621 is repeated three times, and the pressure is increased in step 691. Next time, step 619 will select steps 622 and 623, and thereafter step 619 will select steps 620 and 623. In step 623, it is checked whether the increased pressure counter is 5 or not, and in step 624, it is checked whether the increased pressure counter is 0 or 1. If step 616 is not executed, steps 623, 624, and 627 are repeated twice, and step 691 is executed each time to increase the pressure. However, if step 616 is executed, the above route is repeated once. is selected, the execution of step 691 is stopped, and the pressure is increased. After that, step 624 selects step 625, and step 692 is executed three times until the sudden pressure counter reaches 5, so that the solenoid valve 4
Set 0L to B position. At this solenoid valve position, the hydraulic pressure control valve 24
Then, the spool 25 is stopped and the left driving wheel brake fluid pressure is maintained at the current value. After that, the rapid pressure counter increases to 1.
, 2, n;'H pressure increase, and the left driving wheel brake fluid pressure can be rapidly increased at a speed corresponding to the duty (duty of 215) of holding the pressure at 3 to 5.

The above rapid pressure effect will be explained with reference to FIGS. 11 to 13.

As shown in FIG. 11(a), if the pressure reduction flag = 1 or sudden pressure reduction flag = 1 and the pressure reduction area is switched to the rapid pressure reduction area at instant t1, then the pressure reduction flag = 1 until instant t1.
As will be described later in accordance with No. 1, 112 pressure is applied at a duty of 115 where one cycle is 50 m5ec and the pressure is reduced by 10 m5ec. At instant t, step 614-
The loop of 616-691 is selected once, then steps 618-619-62 (1-623-624, -627
-691 loop is selected once, then step 6I
8-619-620-623-624-625-692
By selecting the loop including three times, it is possible to perform a rapid pressure increase with a duty of <215 as shown by the dotted line in the middle of FIG. 11(a).

As shown in FIG. 11(b), if the pressure reduction area is switched to the rapid pressure area at instant t1 with the pressure reduction flag -O and the sudden pressure reduction flag = 0, then the pressure reduction flag -O until instant t1 is switched to the rapid pressure reduction area.
0 and the sudden pressure reduction flag = 0, the duty is 100% as described later! , continuing to depressurize. At instant t1, the loop of steps 614-613-615-691 is 1
times, and then step 618-619620-6
The loop of 21-691 is selected three times, then steps 618-619-622-623-624-627-6
As a result of the loop No. 91 being selected twice, the initial pressure increase is performed faster than the rapid pressure increase for four times (IT x 4 = 40 m5ec) from the instant tl, resulting in a response delay (Fig. 11).
b) Two times as shown by the dotted line (J TX 2 = 20 m
sec). From then on, 215 is the same as described above.
It is possible to perform a surge pressure due to duty.

Note that, as is clear from the above, on a regular basis, a rapid pressure increase is performed with a duty of 215 as shown in FIG. 12(a).

When step 631 in FIG. 5 is selected for the slow pressure increase area, the unrelated JfiN pressure counter, sudden pressure decrease counter, pressure holding counter, and promotion counter are respectively cleared here. In the next step 632, the previous area is checked, and if it was a depressurized area last time, a loop including step 634 is executed only once, and if it was a pressurized increase or pressure holding area last time, a loop including step 638 is executed. In the former loop, steps 634, 633, 635, and 636 perform the same processing as in steps 614, 613, 615, and 616, but in step 636, a slow pressure increase counter is incremented instead of the rapid pressure counter in step 616. do. Also, steps 638, 639.
640.641.642 as well as step 618.619.
The same processing as 620, 621, and 622 is performed. However, in step 638! , add processing to set the N pressure flag.

At steps 643 and 648, when switching from rapid pressure increase to slow pressure increase, it is checked whether the rapid pressure counter is 5, 0, or something else in order to set a waiting time for the change.

When the rapid pressure counter is other than 0.5, that is, when the rapid pressure is in the middle of rapid pressure, the rapid pressure counter is incremented in step 649, and the pressure is maintained in step 692, and when the rapid pressure counter reaches 5, step 644 is executed. After resetting this counter, if the rapid pressure counter is 0 again, slow pressure increase control is performed using step controllers 45, 646, 647, 650, and 651. This slow pressure increase control is performed in step 62.
3.624.625 This is the same as the sudden pressure control by 626 and 627, but in step 646 corresponding to step 624, the pressure is increased only when the slow pressure increase counter is O, so the duty of 115 is smaller than that during the sudden pressure increase. The pressure can be increased slowly.

The effect of the above-mentioned gradual pressure increase will be explained with reference to FIGS. 11 to 13.

From the instant t in Figures 11(a) and (b) onwards, the switching from pressure reduction to pressure increase is performed in the same way as during the rapid pressure increase, but as the duty is small as mentioned above, the pressure increase is as shown by the solid line in these figures. Pressure time is reduced to 10 m5ec, allowing for gradual pressure build-up.

As is clear from the above, the pressure is steadily increased at a duty rate of 115 as shown in FIG. 12(b).

In addition, if the pressure is switched from the slow pressure increase area to the rapid pressure increase area at instant t1 as shown in FIG. 13(a), the pressure increase starts immediately, but as shown in FIG. If the pressure area switches to the slow pressure increase area, proceed to step 6.
Unnecessary braking can be prevented by delaying the start of gradual pressure increase by the waiting time dt due to the loop including 43.644.648.649.692.

When step 655 in FIG. 5 is selected for the pressure holding area, the initial pressure increase counter, rapid pressure increase counter, and slow pressure increase counter are respectively cleared here, and then step 65
6 to 658, while the holding pressure counter shows 0 to 9, that is, l
Step 692 during a time of tX10=100 m5ec
The solenoid valve 40L is kept at the B position during the next cycle time (l tX 1 = 10 m5ec) in step 691.
to keep the solenoid valve 40L at position C. As a result, the left drive wheel brake fluid pressure can be maintained at the current value as required while replenishing the amount of fluid leakage.

When step 661 in FIG. 5 is selected for the slow pressure increase area, the slow pressure increase counter, rapid pressure increase counter, pressure holding counter, and initial pressure increase counter are respectively cleared here. In the next step 662, it is checked whether the left driving wheel brake fluid pressure PIIL is a low value less than P□ depending on whether the pressure reduction flag is O or not. When the brake fluid pressure PBL is low, that is, when pressure is reduced, this brake fluid pressure becomes O at normal pressure reduction speed.
kgf/cm2, causing the above-mentioned inconvenience, in step 663 the slow pressure reduction cycle TSL is set to a long 7, and if the brake fluid pressure PBL is higher than the PH group, in step 664 the slow pressure reduction cycle TSL is set to 7. By setting the pressure reduction period T1 to a short value of 5, the following slow pressure reduction speed control is performed.

In other words, the slow decompression counter of Stainless Steel 1665 has the slow decompression period "gIT S L < 7 or 5) set as above.
Check whether it has been reached. As long as the no-control flag is determined to be 1 in step 666, the il && pressure counter is counted as 1 in steps 553 and 554 in FIG.
As shown in , since the left drive wheel brake fluid pressure PIIL is more than the minute set value PL, it is incremented at step 673 or 674, which is selected as long as pressure reduction speed control with PIIL<PM is necessary, and this increment causes the set pressure reduction to be controlled. When the period TSL is reached, the 11M pressure counter is reset to 0 in step 675. Also, each time the 11M pressure counter reaches TSL, the promotion counter is incremented in step 676, and after step 674 is executed, the solenoid valve is reset in step 693. 40L is set to position A. At this solenoid valve position, the hydraulic pressure control valve 24L reduces the left driving wheel brake fluid pressure by moving the spool 25 to the left in FIG. 2, and enables re-acceleration after spin suppression of the left driving wheel. Make it familiar.

Step 6 until the slow decompression counter reaches TSL
As long as the no-control flag is determined to be -1 in step 66, the brake fluid pressure is reduced by executing step 693 at a frequency according to the determination result of the low pressure flag (left drive wheel brake fluid pressure) in step 667.

That is, in step 667, the brake fluid pressure is high (PIIL
≧po), the pressure is reduced in step 693 while the 1'JiH pressure counter is 0 to 3 regardless of the promotion counter in step 672, and 1! Decompression counter is 4~
Tst (Tst is now set to 5 in step 664), performing the holding pressure according to step 692;
3/Reduce the brake fluid pressure at a normal speed corresponding to the duty of TSL-315.

In step 667, the brake fluid pressure PBL is low (PBL<
Po), in the initial stage when the promotion counter is determined to be less than 3 in step 668, based on the determination result in step 670, the depressurization in step 693 is performed while the gradual decompression counter is between 0 and 1; is 2~T
SL (TSL is now set to 7 in step 663), perform the holding pressure in step 692, and
The brake fluid pressure put is reduced at an extremely low speed corresponding to the duty of /TSL=1/7.

Thereafter, in the middle period until the promotion counter reaches 6 as determined in step 669, based on the determination result in step 671, while the gradual decompression counter is ON2, step 69
Pressure reduction by 3 and ff [pressure counter is 3~TSL (3
to 7), perform pressure holding in step 692,
The brake fluid pressure is reduced at a slightly faster speed corresponding to the duty of 2/TSL=2/7.

Next, after the promotion counter reaches 6, the gradual decompression counter changes from 0 to 3 based on the determination result in step 672.
While , the pressure is reduced in step 693, and while the slow pressure reduction counter is 4 to TSL (4 to 7), the pressure is maintained in step 692. , but the brake fluid pressure is reduced at a slower rate than normal.

If it is determined in steps 662 and 667 that the brake fluid pressure PBL is a low value below PM, that is, the normal slow pressure reduction speed (speed corresponding to 315 duty as described above)
When the brake fluid pressure is reduced to Okgf/cm2, the next pressure increase cycle is forced to increase the pressure from Okgf/cm2, causing the above-mentioned disadvantage. c).In other words, at the beginning when the promotion counter is ON2, TSL=70 m5
The pressure is depressurized by 10 m5ec during the ec cycle, and in the middle period when the promotion counter is 3 to 5, TSL-10m5ec
The pressure is depressurized by 20 m5ec during the period of TSL-70m5ec after that when the promotion counter is 6 or more.
The pressure is reduced by 0 m5ec. By making the pressure reduction speed slower than usual in this way, the brake fluid pressure PIIL
Even if the brake fluid pressure is low, this brake fluid pressure is O during the pressure reduction cycle.
It is possible to prevent the air pressure from decreasing to kgf/cm2. As a result, the next pressure increase cycle is Okgf/c.
m2, and it is possible to prevent the braking noise of the drive wheels and the vertical vibration of the vehicle body caused by this. By speeding up the decompression speed for each mass in the slow decompression area, it is possible to prevent a delay in depressurization from occurring.

Note that if it is determined in step 666 that the no-control flag is O, that is, if the brake fluid pressure PBL is so low that the pressure reduction speed control described above is unnecessary, step 6 is unconditionally performed.
By continuing to execute 93, the brake fluid pressure is quickly removed.

When step 681 in FIG. 5 is selected for the rapid pressure reduction area, the slow pressure increase counter, rapid pressure increase counter, pressure holding counter, and initial pressure increase counter are respectively cleared here. Then, the control proceeds directly to step 693, and as shown in FIG. 12(d), the duty is 100% and the pressure is rapidly reduced as requested.

Above left driving wheel brake fluid pressure (braking) control (step 5)
Controls similar to those in steps 50 to 693) are executed for the right drive wheel in step 695696, and wheel spin of the right drive wheel is similarly prevented. Note that step 695 corresponds to step 601 in FIG. 4, but steps 550 to 550 in the same figure
It also includes a process corresponding to step 554, and also includes a process corresponding to step 6.
96 corresponds to the control contents of steps 602 to 693.

Thereafter, in steps 701 to 703, the drive control of the hydraulic pump 45 is performed as follows. In step 701, it is checked whether the pressure switch 47 is ON, that is, whether the pressure Pe of the accumulator 43 has reached a predetermined value. The pressure switch 47 switches between 01JL and 12 when the accumulator internal pressure PC drops below P1 as shown in FIG.
It has a hysteresis characteristic that turns off when the voltage rises above this level.

When the pressure switch 47 is turned on, the motor '4 is turned on in step 702.
4 is turned on, the pump 45 is driven to increase the accumulator internal pressure PC, and when the pressure switch 47 is turned off, step 7
At 03, the pump 45 is stopped by turning off the motor 44, and the upper limit of the accumulator internal pressure PC is stopped. Therefore, a predetermined pressure P is always accumulated in the accumulator 43, and it is possible to perform the brake fluid pressure increase control for the traction control.

Next, the throttle valve opening/closing OC■ interrupt flowchart shown in FIG. 6 will be explained. This program is repeatedly executed at a cycle such that the step morph speed determined in step 505 in FIG. 4 is obtained.
Based on the execution result of step 506 in FIG. 4, it is determined whether the step motor 5 should be rotated in the forward direction, reverse direction, or maintained at the current position. If forward rotation is to be performed, the step motor 5 is rotated one step forward in step 801, and if it is to be reversed, the step motor 5 is rotated one step in reverse in step 802.If it is to be held, steps 801 and 802 are skipped. .

Then, in step 803, a motor drive signal is output to the step motor 5, and the throttle valve 4 is opened to an opening degree corresponding to the calculation result in step 503 in FIG.

The traction control based on the drive wheel braking control of the present invention will be explained below based on the operation example shown in FIG. In this operation example, the explanation will be based on the assumption that the left and right drive wheels are synchronized and spin to the same extent. Note that even if the wheel spins of the two driving wheels are different, the braking of both driving wheels is simultaneously controlled in the same manner as described above.

Up to the instant tl, the slip ratio average value SaW is less than S8 and its rate of change SaV is between 0 and SKI, and as is clear from FIG. 9, it is in the slow depressurization area.

Therefore, the brake fluid pressure of both driving wheels is slowly reduced by the above action, and the braking force of these driving wheels is gradually reduced. Instant L
During the period from 1 to t2, the slip rate average value Sav is S.

and 81□, the rate of change is between O and SKI, and as is clear from FIG. 9, it is in the slow pressure increase area. Therefore, the brake fluid pressure of both driving wheels is slowly increased by the above action, and the braking force of these driving wheels is gradually increased. Between instants 12 and 13, the slip rate average value Smv is SII+
As is clear from FIG. 9, the rate of change is positive when the value between SI□ is greater than 2° or the average slip ratio S0 is greater than SI□.

Therefore, the brake fluid pressure of both driving wheels increases rapidly due to the above action, and the braking force of these driving wheels increases rapidly. Instant 13~1
During the period 4, the average value of the slip ratio Sav is S12 or more, and the rate of change is between O and 2□, and as is clear from Fig. 9, it is in the slow pressure increase area, and the control of both driving wheels. Increase power gradually. Between instants 14 and 13, the average slip rate Sa
V has a value between S and SI□, and its rate of change is between 0 and O2□, and as is clear from FIG. 9, it is in the holding pressure area. Therefore, the brake fluid pressure of both driving wheels is maintained at the instantaneous value L4 by the above action, and the braking force of these driving wheels is maintained.

After the instant t, the same area determination based on FIG. 9 is performed,
The brake fluid pressure of both driving wheels is controlled according to the determination result, and the pressure is maintained between instants t and t6, and between instants t6 and t.

Slow pressure increase in between, instantaneous 1? Pressure holding is performed between t8 and t8, and gradual pressure reduction is performed after instant t8.

Therefore, traction control is performed by the drive wheel brake fluid pressure control corresponding to FIG. 9, and drive slip of the drive wheels can be prevented.

However, since the control mode shown in Fig. 9 determines the rate of brake fluid pressure increase and decrease depending on the average value of the slip ratio and the rate of change thereof, under conditions that cause large drive slips or sudden drive slips, slippage may occur. In order to prevent unnecessary braking, the braking speed of the drive wheels can be increased to compensate for the occurrence of this problem, to prevent a decline in traction control performance, or the brake release speed can be increased to match the fact that the drive slip due to braking is quickly settled, to prevent unnecessary braking. can. Conversely, in situations where drive slip is small and occurs slowly, the braking speed may be slowed down to compensate for the occurrence of slip to prevent unnecessary braking, or if the drive slip is slow to subside due to braking. In addition, the brake release speed is slow, which prevents deterioration in traction control performance.

Note that the slip rate setting value S is the standard for determining drive slip that should be performed during engine output (throttle opening) control for traction control and drive wheel braking control.
,, S2 (for engine output control) and Sz, Szz
(for driving wheel braking control) are changed according to the lateral acceleration G in steps 150 and 600, respectively, so the lateral acceleration M (sensitivity) at the start of traction control by engine output control and driving wheel braking is changed as shown in Fig. 16. When the acceleration G is around 0 g (straight ahead) and around 0.4 g or more (high lateral acceleration turning), the speed is relatively slow, and when the acceleration G is around 0.4 g (high lateral acceleration turning), the speed is relatively sharp.

Therefore, it is possible to delay the start of traction control when driving straight ahead or when turning with high lateral acceleration (high friction road) to prevent poor acceleration while driving straight ahead or lack of sharpness when turning with high lateral acceleration. In addition, when the vehicle is turning with low lateral acceleration (low friction road), excluding straight-line driving, traction control can be started earlier to prevent a decrease in turning stability.

In addition, when braking the left and right drive wheels in common as in the illustrated example, the left and right drive slips are detected individually and the left and right drive wheels are brake-controlled individually based on these without correlation. Although the start of traction control tends to be delayed, this delay can be eliminated by making the traction control sensitivity variable according to the lateral acceleration as in the present invention.

17 to 19 show other examples of the present invention. In this example, since the above-mentioned embodiment makes power drift driving difficult for the reason mentioned above, in order to solve this problem, a large lateral acceleration turning state is used. At the beginning of switching from a small lateral acceleration turning state, the traction control sensitivity is kept at a value corresponding to a large lateral acceleration state.

Therefore, the program portion between steps 107 and 151 in FIG. 3 is changed as shown in FIG. 17. Also, in this example, the 9th
In the figure, brake control slip S1. .

In order to make Slt the same as the engine output control fffll slip rate set value SI+Sz in FIG. 7, steps 599 and 600 in FIG. 4 are replaced with step 598 as in FIG. 18.
Replace with

In FIG. 17, in step 121, the average speed of the two front wheels (
Vehicle speed) Based on the table data corresponding to the dashed-dotted line in Fig. 15 from VF, the lower set value S of the slug ratio for engine control,
is looked up and the upper set value S2 is calculated.

In the next step 122, the slip ratio setting value correction coefficient ε corresponding to the lateral acceleration G is looked up from the table data corresponding to the solid line a in FIG. Correct the slip ratio setting value SI+82. In step 124, it is checked whether drive slip is occurring or not, depending on whether the slip rate average value SMV is equal to or higher than the lower set value 31. If slip is not occurring, in step 125, the lateral G flag (old GHG) is checked.
After resetting to 0, control proceeds to step 151.

If a slip is occurring, in step 126 the old GIIG-
2, that is, whether or not it was in the previous Daiken acceleration state. If it is not in the previous major inspection acceleration state, it is checked in step 127 whether the currently detected lateral acceleration G is a large acceleration state of 0.5 g or more, and if it is in the large lateral acceleration state, in step 128 it is checked whether the previous GIIG was non-slip compared to the old GIIG. Check. If it was a slip last time, the correction coefficient ε is set to l in step 129, and if it was a non-slip last time, it is set to HIGIIG=2 in step 130, and then
In step 131, a correction coefficient ε corresponding to the lateral acceleration G is looked up from the table data corresponding to the characteristic shown in FIG.

If it is determined in step 126 that the acceleration state was in the previous major inspection, the current lateral acceleration state is checked in step 132, and if it is also in the large acceleration state this time, the small lateral acceleration counter LOWGC is reset in step 133, and then step 131 is performed. Execute. If it is determined that the current medium lateral acceleration state has occurred, the correction coefficient is applied until the small lateral acceleration counter LOWGC indicates the set time TL in steps 134 to 136, that is, during the initial TL time of transition from large lateral acceleration to small lateral acceleration. ε is set to 1, 25 corresponding to the characteristic C in FIG. 19, after which the counter LOWGC is reset in step 134, the flag old GIIG is set to 1 in step 138, and the correction coefficient ε is determined in step 131. .

In step 139, during the occurrence of drive slip, the slip ratio set values S, , S2 obtained in step 121 are multiplied by the correction coefficient ε determined as described above to correct these set values, and the control proceeds to step 151.

In step 598 in FIG. 18, step 123 (during drive slip not occurring) or step 13 in FIG.
The slip ratio setting values S, , S2 corrected in step 9 (during drive slip) may be set to the brake control setting value SIl+s+z in FIG. 9, respectively.

In this example, during the set time IL when changing from a large lateral acceleration state to a small lateral acceleration state, the correction coefficient ε is maintained at 1.25 for large lateral acceleration in step 135, and the switching of the traction control sensitivity is waited during this time. Therefore, during power drift driving in a state of large lateral acceleration, even if the lateral acceleration decreases due to slipping, power drift driving can be continued.

(Effects of the Invention) As described above, the traction control device of the present invention is configured to change the traction control sensitivity according to the lateral acceleration. By making it relatively dull when driving and making it relatively sharp when driving in a corner with a small lateral acceleration other than going straight, it is possible to prevent poor acceleration while driving straight and a lack of sharpness when driving in a corner with a large lateral acceleration (high friction road). Also, it is possible to prevent a decrease in turning stability during turning with a small lateral acceleration (low friction road).

According to the structure of claim 2, when changing the traction control sensitivity, at the beginning of the transition from the large lateral acceleration state to the small lateral acceleration state, the sensitivity is kept as the sensitivity corresponding to the large lateral acceleration state. Therefore, it is possible to prevent power drift driving from becoming difficult to perform due to the sensitivity change.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of the traction control device of the present invention; FIG. 2 is a system diagram showing an embodiment of the device of the present invention; FIGS. 3 to 6 are flow charts showing the control program of the microcomputer in the same example; Figure 7 is a map of the throttle opening control for traction control used in the same example, Figure 8 is a map of throttle valve opening versus accelerator pedal depression used in the same example, and Figure 9 is a map of the drive used in the same example. 10 is an ON/OFF diagram of the pump in FIG. 2; FIGS. 11 to 13 are waveform diagrams of the electromagnetic valve drive duty in the device shown in FIG. 2, respectively; Fig. 14 is an operation time chart of the tractor engine control by the device of the present invention, Fig. 15 is a change characteristic diagram of the slip ratio set value, Fig. 16 is a change characteristic diagram of the set value correction coefficient, and Figs. 17 and 18 are A flowchart of the main part of a control program showing another example of the present invention, FIG. 9 is a change characteristic diagram of the set value correction coefficient used in this example. IL, IR...driven wheels 2L, 2R...
Drive wheel 4... Throttle valve 5... Step motor 6... Accelerator pedal 8
...Throttle sensor 9...Accelerator sensor 10
...Microcomputer 11...A/D converter 12...F/V converter 13...Motor drive circuit 14...D/A converter 20...Brake pedal 21...Brake master cylinder 22L , 221? , 23L, 23R...Wheel cylinder 24L, 24R...Fluid pressure control valve 40L
, 401? ...Solenoid valve 43...Accumulator
45... Pump 47... Pressure switch 50L, 50R, 51L, 51R... Wheel rotation sensor 52... Lateral G sensor 60L, 60R... Pressure sensor 0 Fig. 8 0 100 (□≦1 n) Press the accelerator firmly into iAcc + ,,, O, □ 7) Turn the needle into a deafening combination, ♂ Fig. 9 Fig. 10 Fig. 1 2 Pc (Accu A leg internal pressure) Fig. 14 O4 5 1,0 Music MJ speed G (chi)

Claims (1)

[Scope of Claims] 1. In a vehicle equipped with a traction control means that prevents drive slip by at least one of braking the drive wheel or reducing the force transmitted to the drive wheel when drive slip occurs in the drive wheel. A traction control device for a vehicle, comprising: a lateral G sensor that detects lateral acceleration of the vehicle; and a sensitivity changing device that changes the sensitivity of the traction control device in accordance with the lateral acceleration. 2. The vehicle traction control device according to claim 1, wherein the sensitivity changing means is configured to maintain the sensitivity of the traction control means corresponding to the large lateral acceleration state at the beginning of switching from the large lateral acceleration state to the small lateral acceleration state. control device.