JPH03125661A - Traction control device for vehicle - Google Patents

Abstract

PURPOSE:To properly maintain the change of driving wheel braking force with each accelerator operation so as to prevent the occurrence of unreasonably large reduction in speed and braking a slip by changing the change speed of the braking force for traction control according to accelerator operating speed. CONSTITUTION:A vehicle is accelerated by changing the driving force of a driving wheel A by accelerator operation, and the driving wheel A is controlled by an automatic brake means B when a driving slip occurs, whereby the driving slip is prevented. In the above constitution, the operating speed of an accelerator C is detected by a means D. According to the detected accelerator operating speed, the braking force change speed of the driving wheel A by the automatic brake means B is changed by a means E. Hence, the change speed of traction controlling braking force by the automatic brake means B is properly maintained with each operation of the accelerator C.

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. 1-85248, there is a type that prevents spinning by braking the spinning drive wheels.

In this type of device, when a wheel drive slip occurs, the drive slip is suppressed by supplying the hydraulic pressure from a hydraulic pressure source provided for traction control to the drive wheel as brake fluid pressure, and when the drive slip is suppressed, the drive wheel is By repeating the cycle of reducing the brake fluid pressure, drive slip can be prevented most efficiently.

(Problems to be Solved by the Invention) However, in the past, brake fluid pressure was increased and decreased at a constant rate, so the rate of change in braking force was not always appropriate, and the following problems occurred. There are concerns.

That is, when the engine brake is requested by suddenly releasing the accelerator pedal during the traction control by braking as described above,
Normally, the braking should be released immediately, but the rate of change in braking force (speed of brake fluid pressure reduction) is too slow, and the braking state due to the remaining brake fluid pressure (residual pressure) is slightly reduced. This continues for a long time, and this combined with the effect of engine braking upon release of the accelerator pedal may cause unnatural deceleration, or even cause braking slip of the drive wheels due to the large deceleration at this time.

However, if the braking force change rate is set to a high speed, the traction control that prevents wheel spin when the accelerator pedal is operated relatively slowly will
The sensitivity is too high, leading to problems such as control hunting.

An object of the present invention is to solve the above-mentioned problem by changing the rate of change in braking force for traction control according to the accelerator operation speed.

(Means for Solving the Problems) For this purpose, the traction control device of the present invention, as conceptually shown in FIG. In a vehicle in which driving slip is prevented by braking by an automatic braking means, an accelerator operating speed detecting means detects an accelerator operating speed, and a braking force of the driving wheels by the automatic braking means is determined according to the accelerator operating speed. A braking force change rate changing means for changing the rate of change is provided.

(Function) The driving force of the wheels is changed by operating the accelerator, accelerating and decelerating the vehicle. When the wheels cause drive slip during acceleration, the automatic braking means brakes the wheels to prevent the drive slip;
When the drive slip is eliminated, the automatic braking means stops braking the wheels.

During such traction control, the braking force change speed changing means changes the braking force change speed of the driven wheels by the automatic braking means in accordance with the accelerator operation speed detected by the accelerator operation speed detecting means.

Therefore, the rate of change of the braking force for traction control by the automatic braking means can be made appropriate for each accelerator pedal, and when the accelerator is suddenly released during traction control to request engine braking,
It is possible to eliminate problems such as a delay in the reduction of the braking force causing deceleration greater than the accelerator operation, or a delay in the rise of the braking force resulting in insufficient prevention of initial drive slip during sudden acceleration due to the accelerator operation.

(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, and the number of steps (opening degree of the throttle valve 4) is set to correspond to the amount of depression of the accelerator pedal 6 by the driver except during traction control. It is controlled by a control circuit 7.

For this purpose, a signal T)l 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 an accelerator sensor that detects the depression of the accelerator pedal 6 1tAcc. The signal from 9 is input to the control circuit 7.

The control circuit 7 includes a micro combinator 10 and an A/D converter 11 and an F/D converter 11 on its input side.
A drive circuit 13 for the step motor 5 and a D/^ converter 14 are provided on the output side. The A/D converter 11 receives the throttle opening signal T.
H and the accelerator signal ACC are analog-to-digital converted and input to the microcomputer 10, and the frequency-to-voltage converted voltage signal is converted to a digital signal by the F/S converter 12 and input to the microcomputer 10.

Each wheel IL, IR, 2L, 2R is a wheel cylinder 22 operated by hydraulic pressure PH from a brake master cylinder 21 according 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 traffic 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 2415 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 boat 30 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 gap between port 29 and 29, 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 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 port-to-port 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 turned ON by a small current. The chamber 31 is cut off from both the drain circuit 42 and the accumulator 43 by entering the boat-to-boat connection position shown in (B), and becomes the boat-to-boat connection position shown by (C) when the solenoid 41 is turned on by a large current. It is assumed that it is cut off from the drain circuit 42 and communicated with the accumulator 43.

When the solenoid valves 40L and 40R are at position (A) 1, the chamber 31 is in a no-pressure state, and the sub-rules 25 are set to the positions shown, and the solenoid valves 40
L.

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 the control circuit 7 stops the motor 44 (pump 45) upon receiving the signal. For this purpose, the signal from the pressure switch 47 is input to the microcomputer 10, and the morph control signal from the micro combinator 10 (No. 8 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 speeds of the corresponding wheels.
, VRLI V+u+4: Generates pulse signals of the corresponding frequency and supplies these pulse signals to the F/V converter 12. The F/Si converter 12 converts each pulse signal into a voltage corresponding to its frequency (wheel rotation speed) and converts it into an A/D converter.
The A/D converter 11 converts these voltages into digital signals and sends 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 drive wheel brake fluid pressures P, PIl, and l, respectively, and signals from these are converted into digital signals by an 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 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 determined within this main routine. 0CI (Output compare 1interr) for driving the step motor is processed at a cycle corresponding to the rotational speed of the step motor 5.
upt) 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. In the next step 103, wheel speeds VFII, VFL, VRL,
Read the VRR, and based on these, set the left and right drive wheels 2L, 2R nozzle') to 7" ratio SL and SR in step 104.
−(VRL VFL)/VF iSR= (VIRV
After calculating from FR) / Vy*d, in step 105, the slip rate change speed of the left and right drive wheels 2L and 2R is calculated as L=S.
L St-+ (where SL-1 is the previous left drive wheel slip rate) and 5ll=SRSll-1 (where SR-1 is the previous right drive wheel slip rate) are determined.

In step 106, the left and right drive wheel slip ratio is 5LSII.
Select the smaller of these low slip rates S. 3. ,,
Set the larger one to the select high slip rate Semx. Next, in step 107, the smaller value Sm of the select low slip rate and the select high slip rate! The weighting of the slip rate that emphasizes +% by the ratio of K (for example, 0.6-0.9) is the average value S, and Smv = KX
S, Sz-+ (1-K)
(However, 5IIV-1 is the average value of the previous slip rate weighting).

In step 151, the throttle opening Tll is determined by the depression amount Δ of the accelerator pedal 6 based on the throttle opening control range data suitable for traction control as shown in FIG. , the direction should be returned (increased) to the value corresponding to the non-control range, or the throttle valve 4 should be suddenly closed (the throttle opening T
Is it a sudden closing range or a slow closing range where the drive slip of the wheels 2L and 2R should be prevented by closing (quickly reducing the throttle opening TH) or a slow closing (gradually reducing the throttle opening TH), or a holding range where the throttle opening TH should be kept unchanged? Determine. This determination result is used in steps 152-1.
54, go to step 201 in the non-control area, go to step 301 in the slow closing area, go to step 351 in the sudden closing area,
In the holding area, 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.
Every time the PUPC indicates a certain recovery time T, that is, every T9 hours, the throttle opening map M is displayed in step 206.
After determining AP as the previous MAPO -1, control proceeds to step 401 . MAP is number 8
As shown in the figure, 20 types are set from the 0th to the 19th map, and the above map up means a command to increase the throttle valve opening to a value corresponding to the accelerator pedal depression amount Acc.

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. In other words, in step 302, the above map up counter l'1APUPc is cleared, and in the next step 3
At 03.304, it is determined whether the left or right pressure reduction flag and the left or right sudden pressure reduction flag are both 0. As will be 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 in a state of slow depressurization for a predetermined period of time or more, or is in a depressurized state for a predetermined period of time or more.
At least one drive wheel is 2. If the pressure is reduced, the map drop number MAPDN is set to 1 in step 305; otherwise, 18 PDN=2 is set in step 306.

In step 307, the larger one (the one with 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 PMAX in the select high-speed engine control. Ste Soph.

In step 308, this select high map MAPMAX is lowered by the number MAPDN determined in step 305 or 306 (MA song AX 1 MAPDIJ) as the current map MAP, and a gradual closing/closing of the throttle opening is commanded. In addition, in steps 309 and 310, if the above-mentioned gate ^P is less than the initial map MAPIN1 obtained when it first changes from the non-control area to the slow-closing area, it means that an increase in throttle opening is commanded, and the slow-closing is Things that go against my intentions l'l
Let AP=MAPINf.

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 the sudden closing region, first the previous throttle opening control region is changed 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 closed or closed from the previous time, the control proceeds directly to step 401; if it was in the slowly closed area or held area last time, step 3
In step 61, the same process as in step 311 is performed, and then 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 range of 0 to 19 shown in FIG. 8 is determined. Cent the outer MAP value to the nearest water boundary 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 2R, 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), the corresponding predetermined time T is determined in step 407. The previous throttle control map is used as PMAP to perform throttle slow/sudden closing control (
If the pressure is increased, then in step 408, T, a longer predetermined time T, and 4 degrees earlier map 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 amount Acc is read. In the next step 503, the step motor 5 is adjusted according to the accelerator pedal depression 1AiLAcc based on the opening characteristic map corresponding to the map MAP obtained as described above.
The target number of steps, 5 TEP, is determined by searching the map.

Further, 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 degree step number Tl+ is calculated by Dif=STEP-T■. Furthermore, in steps 505 and 506, the speed of the step motor 5 is determined, forward rotation/reverse rotation/holding is determined, furthermore, the OCI interrupt period is set, a flag regarding the motor rotation direction, etc. are determined based on the above-mentioned deviation Dir.

In steps 550 to 554, the left driving wheel brake fluid pressure P
Determine whether IL is greater than or equal to the set value p, or less than the minute set value PL, and set the low pressure flag to 1 when PBL≧P, and set the low pressure flag when PL≦pat<214. Reset to 0, P I L < P t.

Reset the no-time control flag to 0.

In steps 556 and 558, the accelerator pedal depression amount A
An engine brake request state in which cc has returned to the previous read value A, (OLD), which is greater than the set value A1, with respect to the read value 10 m5ec ago (updated last time at step 560) corresponding to the calculation cycle ΔT of this braking program. The accelerator operating speed and operating direction are determined based on whether the accelerator pedal is being operated in a gentle manner, whether the accelerator pedal is being pressed for acceleration by more than the set value A2, or whether the accelerator pedal is being operated gently. If the accelerator pedal is returned to 2 to request engine braking, the engine brake flag HNGBF is set to 1 to indicate this in step 557, and the flag ENGBF is set to 1 in step 569 when the accelerator pedal is suddenly depressed to request acceleration. Reset to 0.

Note that in step 560, the ACC(OL) is set for the next time.
D) is updated to the current read value Acc of the accelerator pedal depression amount.

Thereafter, in steps 601 to 693, the left drive wheel is braked and released for traction control at an appropriate speed as follows. In step 601, if the engine brake flag ENGBF=0, then ENGBF=1 based on the table data corresponding to FIG. 9(a).
If so, based on the table data corresponding to FIG. 9(b),
Based on the left driving wheel slip rate SL and its rate of change SL, determine whether the left driving wheel brake fluid pressure should be rapidly increased, gradually increased, held, gradually reduced, or suddenly reduced in the range ( area) to judge. The table data in FIGS. 9(a) and 9(b) is based on the 4PJ mode of controlling the brake fluid pressure of the left driving wheel, which is suitable for traction control, and the slip rate is 5.
The higher the L (Sll, SI2 is the area boundary value) and its rate of change 5L (S21, 0. SZ□ is the area boundary value), the faster the pressure will increase, and the lower the slip rate and its rate of change SL, the faster the pressure will decrease. It should be done. Furthermore, Fig. 9(a),
(b) also shows the right drive wheel brake fluid pressure control mode, which will be described later, and therefore the right drive slip ratio S and its rate of change SR are also shown.

By the way, Fig. 9(b) shows the situation when the accelerator pedal is suddenly released, and compared to Fig. 9(a), the control speed in some areas is changed so that the brake fluid pressure reduction speed is faster in accordance with the above-mentioned request. This is a modified version of .

The above region determination result is determined in steps 602 to 605, and branched to the corresponding step shown 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, control proceeds to step 661 if the area is a slow decompression area, and to step 681 if the area is a decompression area.

When step 611 is selected for the rapid pressure increase area, first, the slow pressure reduction counter, sudden pressure reduction counter, slow pressure increase counter, pressure holding counter, and promotion 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 a decompression area last time, a loop passing through the steering knob 614 is executed only once, and if it was a pressure increase or holding 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 0, that is, whether the pressure has been reduced 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 24L is connected to the spool 25.
As shown 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 0 or the sudden pressure reduction flag is -0, the above-mentioned 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 O or 1 in this case. If step 616 has not been executed, steps 623, 624, and 627 will be repeated twice, and step 691 will be executed each time to increase the pressure, but if step 616 has been executed, the above route will only be executed once. If selected, step 691 is executed to increase the pressure. 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 0 to position B. At this solenoid valve position, the hydraulic control valve 24
L causes the spool 25 to stop moving and maintains the left driving wheel brake fluid pressure at the current value. After that, the rapid pressure counter increases to 1.
Duty to increase pressure when 32 and hold pressure when 3 to 5 (21
It is possible to rapidly increase the left driving wheel brake fluid pressure at a speed corresponding to duty No. 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 is -1 or the 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 L1.
As will be described later in response to
Depressurization is performed by 0m5ec. Gradual depressurization is performed with a duty of 115. Step 614616-6 at instant t1
91 loop is selected once and then step 61B-6
The loop of 19-620-623-624-627-691 is selected once, then steps 618-619-6
By selecting the loop containing 20-623-624-625-692 three times, <27
Rapid pressure increase can be performed with a duty of 5.

As shown in FIG. 11(b), if the pressure reduction area is switched from the pressure reduction area to the rapid pressure area at instant t1 with the pressure reduction flag -O and the sudden pressure reduction flag -○, then the pressure reduction flag -○ and the sudden pressure reduction flag until instant t are - In response to 〇, rapid depressurization continues with a duty of 100% as described below. At instant tI, the loop of steps 614-613-615-691 is selected once, then steps 618,619-620-621
-691 loop is selected three times, then step 61
As a result of the loop 8-619-622-623-624627-691 being selected twice, from instant 1 to 4 times (Δ
T
As shown in the middle dotted line in Figure (b), two doses (ΔT×2 = 2On
Increase the pressure by +5ec). From then on, the same 27 as mentioned above.
A rapid pressure increase with 5 deaTs can be performed.

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
．． 641.642 but step 618.619.620
, 621, 622. However, in step 638, processing for setting the decompression flag to 1 is added.

In steps 643.64.8, when switching from rapid pressure increase to slow pressure increase, the rapid pressure counter is checked to see if it is 5, 0, or something else in order to set a waiting time for the switch. If the value is other than 0 or 5, that is, if it is in the middle of a rapid pressure increase, the pressure increase counter is incremented at step 649, and the pressure is held at step 692. When the rapid pressure counter reaches 5, this counter is incremented at step 644. After resetting , if the pressure increase counter is 0 again, proceed directly to steps 645.646.647.650.
651 to perform slow pressure increase control. This slow pressure increase control is the same as the rapid pressure increase control in steps 623, 624, 625, 626, and 627, but the pressure increase is executed only when the slow pressure increase counter is 0 in step 646 corresponding to step 624. , pressure can be increased slowly with a duty of 115, which is smaller than that during a rapid pressure increase.

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

After instant t1 in Figures 11(a) and (b), the switching from pressure reduction to pressure increase is performed in the same way as during the sudden pressure increase, but as the duty is small as described above, the pressure is increased as shown by the solid line in these figures. The time is reduced to 10 m5ec, allowing for gradual pressure increase.

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

Also, as shown in FIG. 13(a), instant 1. If the pressure is switched from the gradual pressure increase area to the rapid pressure increase area in is step 6
Unnecessary braking can be prevented by delaying the start of gradual pressure increase by the waiting time Δt 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, Δ
The solenoid valve 40L is kept at the B position in step 692 during the time of t
At step 691, the solenoid valve 40L is maintained at the C position. As a result, the left drive wheel brake fluid pressure can be maintained at the current value as requested 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 driving wheel brake fluid pressure PBL is a low value less than PH 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/cm", causing braking noise and vibration, set the gradual pressure reduction cycle TffL to a long value of 7 in step 663. If the brake fluid pressure PBL is a high value of P or more, step 664 to shorten the slow decompression device 5
By setting it to , the following slow depressurization speed control is performed.

That is, in step 665, it is checked whether the slow decompression counter has reached the slow decompression device (7 or 5) set as described above. This slow decompression counter is
As long as the I flag is determined to be 1, that is, as shown in step 553554 in FIG. is incremented in step 673 or 674, which is selected as long as the pressure reduction speed control is necessary, and is reset to 0 in step 675 when the set pressure reduction period T or L is reached by this increment.

Also, each time the slow decompression counter reaches T or L, step 67 is executed.
6, the promotion counter is incremented, and after step 674 is executed, the solenoid valve 401 is set to A in step 693.
position. 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 T3L.
As long as the non-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 (PAIL
≧PH), in step 672, the pressure is reduced in step 693 while the slow decompression counter is between O and 3, regardless of the promotion counter, and when the slow decompression counter is between 4 and T+L (
Tst is now set to 5 in step 664), the holding pressure is executed in step 692, and 3/Ts
The brake fluid pressure is reduced at a normal speed corresponding to the duty of t=315.

In step 667, the brake fluid pressure pmt is low (PBL-
<pl(), in the initial stage when the promotion counter is determined to be less than 3 in step 668, step 67
Based on the determination result of 0, the pressure is reduced in step 693 while the slow pressure reduction counter is O to l, and the slow pressure reduction counter is set to 2.
~T9L (T!L is currently set to 7 in step 663), the pressure holding is performed in step 692, and the brake fluid pressure P is maintained at a low speed corresponding to the duty of 1/T9L=1/7. Depressurize.

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 between 0 and 2, step
3, and the slow pressure reduction counter is 3~T1 (3~7).
[During the period of 2/
The brake fluid pressure is reduced at a slightly faster speed corresponding to the duty of TSL=2/7.

Next, after the promotion counter reaches 6, based on the determination result in step 672, the gradual decompression counter increases from O to 3.
While 3/T!, the pressure is reduced in step 693, and while the slow pressure reduction counter is 4 to T3L (4 to 7), the pressure is maintained in step 692, and 3/T! The brake fluid pressure is reduced at a faster speed corresponding to the duty of L=3/7, but slower than the normal speed.

If it is determined in steps 662 and 667 that the brake fluid pressure PBL is a low value below pH, that is, the normal 412
When the brake fluid pressure is reduced at the pressure speed (speed corresponding to 315 duty as described above), the brake fluid pressure becomes Okgf/CllI2.
Therefore, the next pressure increase cycle is forced to increase the pressure from "Okgf/cm", and the above-mentioned gradual pressure reduction effect when braking noise and vibration occur is shown in Fig. 12 (c). That is,
In the initial stage when the promotion counter is 0 to 2, TAIL =
During the period of 70 m5 ec, depressurization is performed for 10 m5 ec, and in the middle period when the promotion counter is 3 to 5, TSL = 7
During the period of Qmsec, the pressure is depressurized for 20m5ec, and after the promotion counter is 6 or more, T S L = 70m
During a period of 5 ec, the pressure is reduced by 30 m5 ec. By making the pressure reduction speed slower than usual in this way, even if the brake fluid pressure PIIL is low, it is possible to prevent the brake fluid pressure from being reduced to Okgf/cm2 in the pressure reduction cycle. As a result, the next pressure increase cycle will not be from "Okgf/cm", 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 increasing 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 PIIL is so low that the pressure reduction speed control described above is unnecessary, step 693 is continued to be executed unconditionally. Brake fluid pressure should be removed quickly.

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), rapid pressure reduction is performed as requested with a duty of 100%.

Above left driving wheel brake fluid pressure (braking) control (step 5)
The same control as in steps 50 to 693) is also performed 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 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 P2. When the pressure switch 47 is turned on, the motor 44 is turned on by the valve 702.
When the pressure switch 47 is turned on, the pump 45 is driven to increase the accumulator internal pressure Po, and when the pressure switch 47 is turned off, step 70
At step 3, the pump 45 is stopped by the leaf F of the motor 44, and the upper male of the accumulator internal pressure P is stopped. Therefore, a predetermined pressure PC is always accumulated in the accumulator 43, and 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 it is to be reversed, 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.

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, when ENGBF = 0, the left and right driving wheels will be synchronously spun to the same extent, and the explanation will be developed assuming that both driving wheels are simultaneously and similarly brake-controlled.

Up to instant 1, the slip ratio 5L(SR) is less than S11 and the rate of change 5L(SR) is between 0 and 321, which is in the slow depressurization area as is clear from FIG. 9(a).

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 t
Between 1 and t2, the slip rate is between S11 and 31□,
The rate of change is between 0 and S□, and as is clear from FIG. 9(a), 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 t2 and L3,
If the slip ratio is between S ll + s + z, the rate of change is 32□ or more, or if the slip rate is 31□ or more, the rate of change is positive, so as is clear from Figure 9(a), the rapid pressure area is reached. be. 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. Between instant L3 and t4, the slip ratio is greater than or equal to sag and the rate of change is between 0 and SZ2, as shown in Fig. 9 (
As is clear from a), it is in the slow pressure increase area, and the braking force of the driving wheels at both stations increases rapidly. (2) Between time t4 and time t5, the slip ratio is between S11 and SI2, and the rate of change is between 0 and 32□, which is in the holding pressure area as is clear from FIG. 9(a). Therefore, the brake fluid pressure of both station drive wheels is maintained at the instantaneous value L4 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(a) is performed, and the brake fluid pressure of both station wheels is controlled according to the determination result, and the brake fluid pressure is maintained between instants L5 and t7, and between instants L6 and t7. Slow pressure increase, pressure holding between instants 17 and 18, and slow pressure reduction after instant t are executed, respectively.

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

However, since the control mode shown in FIG. 9(a) determines the rate of brake fluid pressure increase and decrease depending on the slip ratio and its rate of change, under conditions that cause large drive slips or sudden drive slips, To prevent unnecessary braking, the braking speed of the driving wheels is increased to compensate for the occurrence of slip to prevent a decline in traction control performance, and the braking release speed is also increased to match the fact that the drive slip due to braking is quickly subsided. Can be done. 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 the drive slip may be slow to subside due to braking). Accordingly, the brake release speed is also slow, which prevents a drop in traction control performance.

By the way, as shown in FIG.
, at 2, and at instant t3, 2. To explain the brake fluid pressure control for traction control when the engine brake is requested in the case where the engine brake is requested in the case of accelerating again, at instant t2 it becomes 8 cc"-1 icc (OLD) <-AI, and at instant L4 Acc-Acc (OLD) ≧ ＾2 becomes tz
-L, the engine brake flag ENGBF is set to 1 to indicate that the engine brake is required due to sudden release of the accelerator pedal.

During this time, the left drive wheel brake fluid pressure region determination at 601 in FIG. 4 and the similar right drive wheel brake fluid pressure region determination at 695 in FIG. Figure (b)
As a result, the brake fluid pressure is reduced at a relatively high speed, and in the engine brake request state, the braking force for traction control of the driving wheels can be quickly reduced. Therefore, no braking force for traction control remains during engine braking, and problems such as unnaturally large deceleration and braking slippage of the drive wheels due to this can be eliminated.

In addition, in the above example, when the accelerator pedal is suddenly released, the release speed of the traction control brake fluid pressure is increased, but when the accelerator pedal is suddenly released, the traction control brake fluid pressure is It is also possible to easily take measures to increase the rate of increase in hydraulic pressure and thereby prevent a delay in the response of the traction control.

(Effects of the Invention) As described above, since the traction control device of the present invention is configured to change the rate of change of the braking force of the driving wheels for traction control according to the accelerator operation speed, the change in the braking force can be made appropriate for each accelerator operation. This makes it possible to prevent unnaturally large deceleration or braking slip of the driving wheels due to a delay in reducing the braking force.

[Brief explanation of the drawing]

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 throttle opening control map 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 Figures 9 (a) and (bl are A region map diagram of the driving wheel brake hydraulic pressure control used in the same example, FIG. 10 is an ON/OFF diagram of the pump in FIG. 2, and FIGS. (
The waveform diagram of the n-valve drive duty, and FIGS. 14 and 15 are operation time charts of the traction control by the device of the present invention, respectively. 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 , 22R, 23L, 23...Wheel cylinder 24L, 24R...Liquid pressure control valve 40L, 4
01'i... Solenoid valve 43... Accumulator 4
5... Pump 47... Pressure switch 50L, 50R, 51L, 51R... Wheel rotation sensor 60L, 60... Pressure sensor

Claims (1)

[Claims] 1. A vehicle in which the driving force of the wheels is changed by accelerator operation to accelerate or decelerate, and the driving wheels are braked by automatic braking means when a driving slip occurs to prevent driving slip, The vehicle is characterized by comprising an accelerator operation speed detection means for detecting an accelerator operation speed, and a braking force change rate changing means for changing the rate of change in braking force of the driving wheels by the automatic braking means in accordance with the accelerator operation speed. Traction control device for vehicles.