JPH0374247A - Traction control device for vehicle - Google Patents

Abstract

PURPOSE:To prevent the stability of a vehicle while running straight at high speed during traction control from deterioration by applying brake to a drive wheel for traction control individually while a vehicle runs at medium or low speed and simultaneously and with the same force at high speed. CONSTITUTION:While a vehicle runs at such low speed as detected by a car speed detecting means 1 of specified value or less, an automatic braking means 3 brakes the right and left drive wheels 4 and 5, wherein drive slipping is generated, individually by an automatic brake control means 2 for preventing drive slipping individually. On the other hand, while a vehicle runs at such high speed of the specified speed or more, the automatic braking means 3 brakes the right and left drive wheels 4 and 5 by the automatic brake control means simultaneously and with the same force and regulates the drive slip of both drive wheels 4 and 5. Thus, the deterioration of the stability while a vehicle runs straight, which is caused by the imbalance of right and left braking force, during traction control at high speed can be prevented.

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) Conventionally, as a traction control device,
As disclosed in Japanese Patent No. 0-56662, there is a type that prevents spinning by braking the spinning drive wheels.

In this type of device, the wheel speeds of the left and right driving wheels are compared with the wheel speeds of the driven wheels, respectively, spin of the left and right driving wheels is determined individually, and the left and right driving wheels are braked individually to suppress wheel spin.

(Problem to be solved by the invention) However, in the conventional device, since the left and right drive wheels are always individually braked, drive slip in the medium and low speed range cannot be properly prevented and stability during starting and acceleration cannot be ensured. However, the following issues are of concern.

That is, in a high vehicle speed range, the gear ratio of the transmission is small, so the rotational inertia of the drive wheels is small.

Therefore, if braking is controlled individually for the left and right drive wheels in the high vehicle speed range as it is easy for braking to be effective, one-sided braking effect based on the difference in left and right braking force will become noticeable and the vehicle straight-line stability is impaired. This tendency becomes particularly noticeable when the differential gear between the re-driven wheels does not have a differential limiting mechanism.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem by performing braking in common for traction control of left and right drive wheels at high vehicle speeds, rather than independently.

(Means for Solving the Problems) For this purpose, the present invention provides a vehicle equipped with automatic braking means for braking the left and right drive wheels when drive slip occurs to prevent drive slip, as shown in the concept in FIG. The traction control device includes a vehicle speed detection means for detecting vehicle speed, and an automatic braking means that functions so that the left and right drive wheels are braked with separately determined forces when the vehicle speed is less than a set vehicle speed, and when the vehicle speed is higher than the set vehicle speed. The vehicle is configured to include automatic brake control means for operating the automatic brake means so that the left and right drive wheels are braked simultaneously with the same force.

(Function) When the vehicle speed is lower than the vehicle speed detected by the vehicle speed detection means or a set value, the automatic brake control means individually brakes the left and right drive wheels that have experienced drive slip to individually prevent drive slip.

On the other hand, when the vehicle speed is higher than the set value, the automatic brake control means functions to brake the left and right driving wheels simultaneously with the same force, thereby comprehensively suppressing the drive slip of both side driving wheels. do.

Therefore, the braking forces of the left and right drive wheels are made the same at the high vehicle speed, and it is possible to eliminate the problem of lack of straight-line stability that has conventionally occurred due to the braking forces being different at high vehicle speeds.

(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, where LL 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). It is assumed that the vehicle travels by driving wheels 2L2R by an engine (not shown), and the output of the engine is adjusted 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 TH from a throttle sensor 8 that detects the opening degree of the throttle valve 4 and the number of steps of the throttle motor 5 is fed back to the control circuit 7, and the amount of depression A of the accelerator pedal 6 is determined. Accelerator sensor 9 that detects C
The signal from the controller is input manually to the control circuit 7.

The control circuit 7 includes a microcomputer 1o, and an A/D converter 11 and an F/F/D converter 11 on the input side thereof.
A drive circuit 13 for the step motor 5 and a D/A converter 14 are provided on the output side. The A/D converter 11 receives the throttle opening signal T.
H and accelerator signal Acc are analog-to-digital converted and input to the microcomputer 10, and F/V
The converter 12 converts the frequency-voltage converted voltage signal into a digital signal and inputs it to the microcomputer 10 manually.

Each wheel IL, IR, 2L, 2R is a wheel cylinder 22L operated by hydraulic pressure PM from a brake master cylinder 21 corresponding to the depression force of the brake pedal 20.

22R, 23L, and 23R, 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 have a hydraulic pressure control valve 24L for traction control.
, insert 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 inlet port 29 on the master cylinder side as it is to the corresponding wheel cylinder from the outlet port 3o on the wheel cylinder side in the normal state shown in the figure, and causes the spool 25 to move to the right. When the spool 25 stops moving to the right, the plunger 27 shuts off the port 1-29.30 and increases the hydraulic pressure to the wheel cylinder, and maintains the increased hydraulic pressure in the wheel cylinder when the spool 25 stops moving to the right.

The movement of the spool 25 to the right and its stopping are controlled by the pressure within the chamber 31, and this pressure is individually controlled by the respective solenoid valves 40L40R. 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 ( The chamber 31 is in the port-to-port connection position shown in B).
is cut off from both the drain circuit 42 and the accumulator 43, and when the solenoid 41 is turned on due to a large current, the port is in the port-to-port connection position shown in (C), cutting off the chamber 31 from the drain circuit 42 and communicating 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 accumulates hydraulic pressure from a pump 45 driven by a motor 44 via a check valve 46, and the accumulated pressure value of the accumulator 43 is kept at a constant value P. It is assumed that the control circuit 7 stops the motor 44 (pump 45) in response to a signal from the pressure switch 47, which detects this and turns OFF when this occurs. For this purpose, the signal from the pressure switch 47 is input to the microcomputer 1o, 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 electromagnetic valves 40L and 40R is also driven and controlled by the microcomputer 10, and the control signal therefor is converted into an analog signal by the D/A converter 14 and supplied to the solenoid 41.

Wheel rotation sensors 50L, 50R, 51L, and 51R are provided in association with each wheel IL, IR, 2L, and 2R, respectively, and these sensors detect the wheel speed of the corresponding wheel, VFL+VFR=
ν. Pulse signals having a frequency corresponding to L+vRR are generated and these pulse signals are supplied to the P/V converter 12. The F/shikonhak 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 and inputs them to the microcomputer. 1
Enter 0.

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 manually.

The microcomputer 10 executes the control programs shown in FIGS. 3 to 6 based on various 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 (hydraulic 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 that is determined within this main routine. ○CI for step motor drive (Output compare 1nt
errupt) 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.
)I, etc. In the next step 103, wheel speed VFRI VFL, VRL,
The VRM is read, and based on these, in step 104, the left and right drive wheels 2L, 2R (71 slip ratio SL, SR are set to 5L)
-(VRL-VFL)/VFL, 5ll-(VIIR
VFR) / After determining by VFR, step 105
The slip rate change speed of left and right drive wheels 2L and 2R is 5L =
SL 5L-1 (However, SL, I is the previous left driving wheel slip rate) and 5R=SR5R-1 (However, s, -1
is the previous right drive wheel slip rate).

In step 106, the smaller of the left and right drive wheel slip rates SL0 and SR is selected as the low slip rate Smr,
,,Set the larger one to select high slip rate S0. Next, in step 107, the smaller value Smi of the select low slip rate and the select high slip rate is determined. The weighting of the slip rate is based on the ratio of K (for example, O, 10, 9), and the average value Snv is 5aV = 4XS
, i, + (1-K)
However, 5av-+ is the previous slip rate weighted average value)
seek.

In step 150, the lower set value S1 of the slit ratio for engine output control necessary for traction control is looked up based on the average speed (vehicle speed) of the front two wheels (vehicle speed), and further, the engine output control necessary for traction control is performed using the following equation. The upper set value S2 of the slibbing ratio is calculated.

In the next step 151, the above slip rate average value Sm
v and its rate of change Snv, the throttle opening TH is adjusted to a value corresponding to the depression amount ^cc of the accelerator pedal 6 based on throttle opening control range data suitable for traction control as shown in FIG. 7(b). should be returned to (increased) in the uncontrolled range, or close the throttle valve 4 quickly (suddenly decrease the throttle opening TH) or slowly close it (slowly decrease the throttle opening TH) to prevent drive slip of the wheels 2L and 2R. It is determined whether the throttle opening TH should be kept unchanged in the rapid closing range or the slow closing range. Step 1
52 to 154, go to step 201 in the non-control area, go to step 301 in the slow closing area, and step 3 in the sudden closing area.
The control proceeds to step 51, and to step 401 in the holding area.

In the non-control area, in steps 201 to 20G, the map up counter MA is cleared in step 204 and incremented (stepped) in step 203 or 205.
Every time the PUPC indicates a certain recovery time TR, that is, every 18 hours, the throttle opening map M is
After determining the AP as the previous map (MAPO)-1, control proceeds to step 401. As shown in Figure 8, 20 types of maps are set from the 0th map to the 19th map, and the above map raising is a command to increase the throttle valve opening to a value corresponding to the accelerator pedal depression amount cc. It means something.

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 step 306, the map dropout number MAPDN is set to 1, and in other cases, MAPDN=2 is set in step 306.

In step 307, the larger one (the smaller throttle opening) of the previous map MAP O and the map number PMAP stored a predetermined time ago stored in memory as described later is set as the select high map MAPMAX, and in step 308, this select High map MAPMAX step 305
Alternatively, the current map is set by dropping the map by the number MAPDN determined in step 306 (MAPMAX + MAPDN), and commands are given to gently close and close the throttle opening. In addition, in steps 309 and 310, the initial map MA obtained when the above MAP first changes from the uncontrolled region to the loosely closed region is
When it is less than PINI, it means commanding an increase in the throttle opening, which goes against the intention of loose closing, so MAP=MA
Let it be PINI.

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 MA is the one in which PO is dropped by 1.
After issuing a command to reduce the throttle opening as P, the control proceeds to step 401.

If the control proceeds to step 351 due to the sudden closing region, first, the previous throttle opening control region is checked here. If it was in the non-control area last time, steps 352~
In step 360, the same processing as in steps 302 to 310 is performed, and in step 362, 2 is further added to the map obtained by this processing to command a sudden decrease in the throttle opening, after which the control proceeds to step 401. If it is determined in step 351 that it was in the sudden closing region from the previous time, the control proceeds directly to step 401, and if it was in the slow closing region or holding region last time, in step 361, the same processing as in step 3H is performed, and then the control is continued to step 401. Proceed to 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. Cent the outer MAP value to the nearest limit value O or 19. In the next steps 405 and 406, the brake fluid pressure increase state of the left and right drive wheels 2L and 2B, where both the left and right pressure reduction flags are not 0 and the left and right sudden pressure reduction flags are not 0, is checked. If the pressure is not increased (if the pressure is decreased), in step 407, the throttle slow/sudden closing control (
Steps 307 and 357) are used, and if the pressure is increasing, T in step 408, and the map before THI for a longer predetermined time is P.
Let it be MAP. In the next step 409, the current map MAP is stored as the previous map MAPO in preparation for the next map.

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 amount Acc 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 Dif between EP and the actual opening degree step number TH is calculated by Dif=STEP-TH. Furthermore, in steps 505 and 506, the speed of the step motor 5 is determined based on the deviation Dir, the regulation of forward rotation/reverse rotation/holding is determined, the OCI interrupt period is set, a flag regarding the motor rotation direction, etc. are set.

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 Po, less than the minute set value PL, or less than PL, and set the low pressure flag to 1 when PBL≧PM, and set the low pressure flag to 0 when PL≦PBL<PH. and reset the no-control flag to O when PBL<PL.

In step 598, the vehicle speed vF is set to 60 km/h.
Check whether the vehicle speed is higher than 601an/h or lower than 601an/h. If the vehicle speed is high, the left and right driven wheels speed VFL+VF is set in step 599 in order to simultaneously brake the left and right driven wheels with the same force for traction control, which will be described later.
R is set to the same vehicle speed VF, the slip ratios SL and SR of the left and right driving wheels are respectively set to the weighted average value Sav, and the slip rate of change SL and SR of the left and right driving wheels is set to the average value Sav.
The weighting is set to the average value change rate Sav. Therefore, if the vehicle speed is low, step 599 is not executed and v
By using FL, VFR, SL, SR, and 5LSR as they are, braking of the left and right drive wheels is performed under individual control.

Thereafter, in steps 600-693, the left drive wheel is braked and unbraked for traction control at an appropriate speed as follows. In step 600, left front wheel speed VF
Look up the slip ratio lower set value S11 for driving wheel braking required for traction control based on the table data corresponding to FIG. The upper set value S, □ of the slip ratio is calculated.

In the next step 601, the left driving wheel slip rate SL and its change rate SL are calculated based on the table data corresponding to FIG.
Determine whether the left drive wheel brake fluid pressure should be rapidly increased, gradually increased, or maintained. The table data in Fig. 9 shows the control mode of the left drive wheel brake fluid pressure suitable for traction control. It is assumed that the lower the slip ratio SL and its rate of change SL, 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, and therefore the right drive shaft slip ratio SR and its rate of change SR are also shown.

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.
5, the control proceeds to step 661 if the area is a slow decompression area, and to step 681 if the area is a rapid decompression area.

When step 611 is selected for a rapid pressure increase area, first, a slow pressure reduction counter, a sudden pressure reduction counter, a slow pressure increase counter, a pressure holding counter, and an increase counter that are not related to the sudden pressure increase are cleared.

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 rapid pressure reduction flag are O, that is, whether rapid pressure reduction has been performed for a predetermined period of 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 24I7 is connected to the spool 2.
5 in FIG. 2, the left driving wheel brake fluid pressure is increased and the left driving wheel is braked for traction control. Therefore, if the pressure reduction flag is not O or the sudden pressure reduction flag is -O, the above-mentioned initial pressure increase is not necessary, so step 61
Increment the rapid pressure counter at step 6 and proceed to step 69.
Execute 1.

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 0, but if step 615 has been executed, the pressure increase is repeated in step 691 while repeating the path of steps 619, 620 and 621 three times, 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 sudden pressure counter is 5 or not, and in step 624 it is checked whether this sudden pressure counter is O or 1. If step 616 has not been executed, the routes of steps 623, 624 and 627 will be repeated twice and the pressure will be increased by executing step 691 each time, but if step 616 has been executed, the above route will be selected only once. Then, step 691 is executed to increase the pressure. After that, step 624 is step 62
5 is selected, and by executing step 692 three times until the rapid pressure counter reaches 5, the solenoid valve 40L is selected.
to position B. At this solenoid valve position, the hydraulic pressure control valve 24I,
Then, the spool 25 is stopped moving and the left driving wheel brake fluid pressure is maintained at the value at this time. After that, the rapid increase pressure rank was 1.
Duty to increase pressure at 2 and hold pressure at 3 to 5 (215
The left drive wheel brake fluid pressure can be rapidly increased at a speed corresponding to the duty (duty).

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 area is switched to the rapid pressure area at instant t with the pressure reduction flag -1 or sudden pressure reduction flag -1, then the pressure reduction flag is -1 until instant t.
In response to this, as will be described later, gradual pressure reduction is performed at a duty rate of 115 in which one cycle is <50 m5ec and the pressure is reduced by 10 m5ec. Instant 1. Steps 614-616
-691 loop is selected once and then step 618
-619-620-623-624-627-691 loop is selected once, then step 618619-
By selecting the loop including 620-623-624-625-692 three times, <2
Rapid pressure surge can be performed at 75 duty.

As shown in FIG. 11(b), if the pressure reduction area is switched to the rapid pressure area at instant tl with the pressure reduction flag -○ and sudden pressure reduction flag -○, then the pressure reduction flag is -0 until instant t1.
In response to the sudden pressure reduction flag -0, the rapid pressure reduction with a duty of 100% is continued as described later. At the instant t, steps 614-613-615-
691 loop is selected once and then step 618
-619620-621-691 loop is selected 3 times, then step 6]8-619-622-623-
The loop 624-627-691 is selected twice, resulting in instant 1. 4 times (JTX 4 = 40 m5ec
), the initial pressure is increased faster than the rapid pressure increase to eliminate the response delay, and then the pressure is increased twice (,
! III T x 2 = 20 m5ec). Thereafter, it is possible to perform a sudden pressure increase with a duty of 275 as described above.

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, first, the unrelated slow pressure decrease counter, rapid pressure decrease counter, pressure holding counter, and promotion counter are respectively cleared here. In the next step 632, check the previous area,
If the area was previously in a depressurized area, the loop including step 634 is executed only once; if the area was previously in the pressure increase or hold area, the 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 increase counter in step 616. Also, step 638.639.640
．． 64L 642 but step 618.619.620
, 62L Performs the same processing as 622. However, in step 638, processing for setting the sudden pressure reduction flag to 1 is added.

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 O again, slow pressure increase control is performed in steps 645, 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.

Moment 1 in FIGS. 11(a) and (b). Thereafter, the switch from pressure reduction to pressure increase is carried out in the same way as during a rapid pressure increase, but as the duty is small as mentioned above, the pressure increase time is shortened to 10 m5ec as shown by the solid line in these figures, making it possible to gradually increase pressure. Make it.

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, when switching from a slow pressure increase area to a rapid pressure increase area at instant t as shown in FIG. 13(a), rapid pressure 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 5t, which is the waiting time 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 O to 9, that is, l
Step 692 during a time of tX10=100 m5ec
and keep the solenoid valve 40L at the B position during the next cycle time (d tX 1 = 10 m5ec) in step 69.
1 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 gradual pressure reduction 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 drive shaft brake fluid pressure PBL is a low value less than PM 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 is OK at normal pressure reduction speed.
gf/cm25 G, causing the above-mentioned inconvenience, in step 663 the slow decompression cycle TSL is set to a long 7,
If the brake fluid pressure PBL is a high value of 111 or more,
By setting the gradual pressure reduction period TSL to a short value of 5 in step 664, the following slow pressure reduction speed control is performed.

That is, in step 665, it is checked whether the slow decompression counter has reached the slow depressurization period TSL (7 or 5) set as described above. This slow decompression counter is
As long as the no-control flag is determined to be 1 in step 66, that is, as shown in steps 553 and 554 in FIG.
It is assumed that the depressurization speed control with P s L < P ++ is incremented in a selected step 673 or 674 as long as it is necessary, and is reset to 0 in step 675 when the set depressurization period TSL is reached by this increment. Further, each time the gradual pressure reduction counter reaches TSL, the promotion counter is incremented in step 676, and after step 674 is executed, the solenoid valve 40L is set to the A position in step 693. At this solenoid valve position, the hydraulic pressure control valve 24L reduces the left driving wheel brake hydraulic pressure by moving the spool 25 to the left in FIG. 2, making it possible to re-accelerate the left driving wheel after spin suppression.

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 shaft brake fluid pressure) in step 667.

That is, in step 667, the brake fluid pressure is high (PBL≧
P, ), step 672 determines that the gradual decompression counter is between 0 and 3 regardless of the promotion counter.
93, and the slow depressurization counter is 4 to T3L (T3L).
SL is now set to 5 in step 664), the holding pressure is performed in step 692, and 3/TSL
-Reduce the brake fluid pressure at a normal speed corresponding to the duty of 315.

In step 667, the brake fluid pressure PBL is low (PBL<
PM), 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 O and 1; is 2~T
SL (TSL is now set to 7 in step 663), perform the holding pressure in step 692, and
/Ts The brake fluid pressure pBt is reduced at an extremely low speed corresponding to the duty of L=1/1.

Thereafter, in the middle period until the promotion counter becomes 6 as determined in step 669, based on the determination result in step 671, while the gradual decompression counter is O~2, step 69
3, and the slow depressurization counter is 3~TSL (3~
7) while performing the pressure holding in step 692;
/TSt, the brake fluid pressure is reduced at a slightly faster speed corresponding to the duty of -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 slow pressure reduction counter is 4~Ts+14~7), the pressure reduction is performed in step 693, and the pressure retention is performed in step 692 while the slow depressurization counter is 4~Ts+14~7), at a faster speed corresponding to the duty of 3/TSL""3/7, but If it is determined in step 662 or 667 that the brake fluid pressure PIL is a low value less than P)1, that is, the normal slow pressure reduction speed (31
When the pressure is reduced at a speed corresponding to 5 duty, the brake fluid pressure becomes Okgf/cm'' and the next pressure increase cycle is Okgf/cm''.
Figure 12 (C
). That is, in the initial stage when the promotion counter is O~2, 10 m5e during the period of TsL-10m5ec.
In the middle period when the promotion counter is 3 to 5, the pressure is reduced by 20 m5ec during the period of TSL-7Q m5ec.
is decompressed, and after that the promotion counter is 6 or more, T
The pressure is reduced by 30 m5ec during the period of st-70m5ec. By making the pressure reduction speed slower than usual in this manner, even if the brake fluid pressure PBL is low, it is possible to prevent the brake fluid pressure from decreasing to Okgf/cm2 in the pressure reduction cycle. As a result, the next pressure increase cycle will not be from Okgf/cm2, and this will prevent the braking sound of the drive wheels and vertical vibration of the vehicle body from occurring. . By gradually increasing the pressure reduction speed while in the slow pressure reduction area, it is possible to prevent a pressure reduction delay 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)
50-554 and 600-693) is also performed for the right drive wheel in steps 695 and 696, and wheel spin of the same drive wheel is similarly prevented. Note that step 695 corresponds to step 601 in FIG. 4, but also includes processing equivalent to steps 550 to 554 and 600 in the same figure, and step 696 corresponds to step 601 in FIG.
This corresponds to control contents 2 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 PC of the accumulator 43 has reached a predetermined value. As shown in FIG. 10, the pressure switch 47 has a hysteresis characteristic that turns ON when the accumulator internal pressure PC falls below P1, and turns OFF when it rises above 12. When the pressure switch 47 is turned on, in step 702, the motor 44 is turned on to drive the pump 45 and reduce the accumulator internal pressure P.
Step 70 when increasing the C and turning off the pressure switch
3, the pump 45 is stopped by turning off the motor 44, and the increase in the accumulator internal pressure PC is stopped. Therefore, a predetermined pressure PC is always accumulated in the accumulator 43,
The brake fluid pressure increase control for the traction control can be performed.

Next, the OCI interrupt flowchart for opening and closing the throttle valve shown in FIG. 6 will be explained. This program is repeatedly executed at a cycle such that the step motor 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 set to one-step forward rotation in step 801, and if reverse rotation is to be performed, step motor 5 is set to one-step reverse rotation in step 802. If it is to be maintained, 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 set to the opening degree corresponding to the calculation result in step 503 in FIG.

Traction control using the drive wheel braking control section 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, and that the same drive wheels are simultaneously and similarly brake-controlled.

Up to instant t, the slip ratio SL (sa+) is less than 311 and its rate of change 5L (SR) is between 0 and SZ+, and as is clear from FIG. 9, it is in the slow depressurization area.

Therefore, the brake fluid pressure of the driving wheels is slowly reduced by the above action, and the braking force of these driving wheels is gradually reduced. instant 1
Between 1 and 12, the slip ratio is between Sl+ and 31□,
The rate of change is between 0 and 32I, and as is clear from FIG. 9, it is in the slow pressure increase area. Therefore, the brake fluid pressure of the driving wheels is slowly increased by the above action, and the braking force of these driving wheels is gradually increased. Between instants t2 and t3, the slip ratio is between 5l131□ and its rate of change is 521
If the slip ratio is 31□ or more, the rate of change is positive, so as is clear from FIG. 9, the slip ratio is in the rapidly increasing pressure area.

Therefore, the brake fluid pressure of the driving wheels increases rapidly due to the above action, and the braking force of these driving wheels increases rapidly.

Between instants 13 and 14, the slip ratio is SI2 or more and the rate of change is between O and 32□, and as is clear from Fig. 9, it is in the slow pressure increase area, and the braking force of the driving wheel is Increase gradually. Between instants t4 and t5, the slip 3 4 ratio is between S and 312, and its rate of change is between O and 2□, and as is clear from FIG. 9, it is in the holding pressure area. Therefore, the brake fluid pressures of both station drive wheels are maintained at the value at instant t4 by the above-mentioned action, and the braking force of these drive wheels is maintained.

After the instant t, the same area determination based on FIG. 9 is performed,
The brake fluid pressure of both station wheels is controlled according to the judgment result, and the pressure is maintained between instants 15 and 16, the pressure is slowly increased between instants t6 and t7, the pressure is maintained between instants t7 and tl1, and the pressure is slowly decreased after instant t8. are executed respectively.

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 slip ratio and its rate of change, slips may occur under conditions that cause large drive slips or sudden drive slips. It is possible to increase the braking speed of the drive wheels to match this, to prevent deterioration in traction control performance, or to increase the speed at which the brake is released, as drive slip due to braking settles down quickly, 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.

By the way, in steps 598 and 599, if the vehicle speed is high, the information used to determine drive slip is the same for the left and right drive wheels (VFL-VF□5L-SR,S).

=SR), at the high vehicle speed, the braking that should be performed for traction control of the left and right drive wheels is performed at the same time and with the same force. Therefore, at high vehicle speeds, the braking force for traction control on the left and right drive wheels can be made the same.
It is possible to prevent deterioration in straight-line stability during traction control at high vehicle speeds, which conventionally occurred because these were different from each other.

(Effects of the Invention) Thus, as described above, the traction control device of the present invention can appropriately prevent drive slips at the time of starting, etc. by individually braking the drive wheels for traction control at medium and low speeds, and at the same time, at high speeds At vehicle speeds, the braking of the left and right drive wheels for traction control is performed simultaneously and in the same way, so during traction control at high vehicle speeds, the deterioration of straight-line stability that conventionally occurs due to the imbalance of left and right braking forces can be avoided. It can be prevented.

[Brief Description of the 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, and Figs. 3 to 6 are diagrams of the microcomputer in the same example. Flowchart showing the control program, FIG. 7(a)
is a change characteristic diagram of the slip ratio lower setting value used to determine drive slip in the same example, Figure (b) is a throttle opening control map diagram for traction control used in the same example, and Figure 8 is a map diagram used in the same example. Map of throttle valve opening relative to accelerator pedal depression, No. 9
The figure is a region map of the drive wheel brake fluid pressure control used in the same example, Figure 10 is the pump ON/OFF diagram in Figure 2, and Figures 11 to 13 are the electromagnetic diagrams in the device in Figure 2. A waveform diagram of the valve driving duty, and FIG. 14 is an operation time chart of the traction control by the device of FIG. 2. IL, IR...driven wheels 2L, 2R...
Drive wheel 4... Throttle valve 5... Step motor 6... Accelerator pedal 8
...Throttle valve 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 7-8 221.221? , 231.23R...wheel cylinder 24L, 24R...hydraulic pressure control valve 40L,
40R...Solenoid valve 43...Accumulator 45
...Pump 47...Pressure switch 50L, 50R, 51L, 51R...Wheel rotation sensor 60L, 60R...Pressure sensor 9 1st Japanese Unexamined Patent Publication No. 3 74247 (17) Seitaibe ψd 沫も 0 HISTORY BEBEMA）←Yin

Claims (1)

[Scope of Claims] 1. A traction control device for a vehicle equipped with automatic braking means for braking left and right drive wheels when a drive slip occurs to prevent drive slip, comprising: a vehicle speed detection means for detecting vehicle speed; An automatic brake that causes the automatic braking means to function so that the left and right drive wheels are braked with individually determined forces, and also causes the automatic braking means to function so that the left and right drive wheels are simultaneously braked with the same force when the vehicle speed is equal to or higher than the set vehicle speed. A traction control device for a vehicle, comprising a control means.