JPH0788160B2 - Vehicle acceleration slip prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a vehicle acceleration slip prevention device capable of preventing an uncomfortable steering wheel shock at the start of braking on a split road.

(Prior Art) Conventionally, there is known an acceleration slip prevention device (traction control device) that prevents slippage of drive wheels that occurs when an automobile is suddenly accelerated. In such a traction control device, when the acceleration slip of the driving wheels is detected, the slip ratio S is controlled so that the friction coefficient μ between the tire and the road surface is in the maximum range (hatched range in FIG. 18). Here, the slip ratio S is [(VF-VB) / V
F] × 100 (percent), VF is the wheel speed of the drive wheels, and VB is the vehicle speed. That is, when the slip of the driving wheel is detected, the wheel speed VF of the driving wheel is controlled by controlling the engine output so that the slip ratio S is in the shaded range, and the friction coefficient μ between the tire and the road surface is maximum. The range is controlled so that the drive wheels do not slip during acceleration and the acceleration performance of the vehicle is improved. A trunkion control device has also been considered in which such engine output control and independent brake control for the left and right drive wheels are used together to prevent acceleration slip of the vehicle.

(Problems to be Solved by the Invention) Using the above traction control device, when braking is started on a split road where the friction coefficient μ between the road surface and the tire is different between the left wheel side and the right wheel side, a low friction coefficient μ Since a large braking force is applied to the driving wheels on the road surface, the inputs to the steering system are different between the left and right wheels, which causes steering wheel sickness, which is uncomfortable.

The present invention has been made in view of the above points, and an object thereof is to provide an acceleration slip prevention device for a vehicle capable of preventing an uncomfortable steering wheel shock at the start of braking on a split road.

[Configuration of the Invention] (Means and Actions for Solving the Problem) The vehicle is equipped with braking means capable of individually braking the left and right drive wheels, and when a slip occurs on the drive wheels, depending on the slip state. In an acceleration slip prevention device for a vehicle that controls the braking means to reduce the slip,
The slip state amount indicating the magnitude of the slip actually occurring on one of the left and right drive wheels and the magnitude of the slip actually occurring on the other drive wheel of the left and right drive wheels are represented by The slip detecting means for detecting the slip state amount and the slip state amount of both driving wheels detected by the slip detecting means at the start of the control of the braking means are equalized to the left and right by the braking means. Then, the braking force of the braking means for the drive wheel having the larger slip state is applied to the drive wheel having the smaller slip state according to the slip state amount of each drive wheel detected by the slip detecting means. A traction controller that makes the braking force larger than the braking force of the braking means is provided.

(Embodiment) Hereinafter, an acceleration slip prevention device for a vehicle according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an acceleration slip prevention device for a vehicle. The figure shows a front-wheel drive vehicle. WFR is the front right wheel, W
FL is the front left wheel, WRR is the rear right wheel, and WRL is the rear left wheel. Further, 11 is a wheel speed sensor for detecting the wheel speed VFR of the front right wheel (driving wheel) WFR, 12
Is a wheel speed sensor for detecting the wheel speed VFL of the front left wheel (driving wheel) WFL, 13 is a wheel speed sensor for detecting the wheel speed VRR of the rear right wheel (driving wheel) WRR, and 14 is a rear left wheel (driving wheel). Wheel) A wheel speed sensor for detecting the wheel speed VRL of WRL. The wheel speeds VFR, VFL, VRR, VRL detected by the wheel speed sensors 11 to 14 are traction controllers.
Entered in 15. The traction controller 15 sends a control signal to the engine 16 to perform braking to prevent the drive wheels from slipping during acceleration. This engine 16 is a main throttle valve whose opening is operated by an accelerator pedal.
In addition to THm, a sub throttle valve whose opening is controlled by a control signal Θs from the traction controller 15 described above.
It has THs, and controls the driving force of the engine 16 by controlling the opening of the sub-throttle valve THs by a control signal from the traction controller 15.

Further, 17 is a wheel cylinder as a braking means for braking the front right wheel WFR, and 18 is a wheel cylinder as a braking means for braking WFL of the front left wheel.
Normally, pressure oil is supplied to these wheel cylinders by operating a brake pedal (not shown) through a master bag and a master cylinder (not shown). When the traction control is activated, pressure oil can be supplied from another route described below. Above wheel cylinder 17
Pressure oil from the hydraulic source 19 to the inlet valve 17i
Through the wheel cylinder 17 from the reservoir
The pressure oil is discharged to 20 through the outlet valve 17o. Further, the pressure oil is supplied to the wheel cylinder 18 from the hydraulic pressure source 19 through the inlet valve 18i, and the pressure oil is discharged from the wheel cylinder 18 to the reservoir 20 through the outlet valve 18o. The traction controller 15 controls the opening and closing of the inlet valves 17i and 18i and the outlet valves 17o and 18o.

Next, referring to FIG. 2, the traction controller described above.
The detailed configuration of 15 will be described. The wheel speeds VFR and VFL of the drive wheels detected by the wheel speed sensors 11 and 12 are sent to the high vehicle speed selection section (SH) 31 and the larger wheel speed is selected from the wheel speed VFR and the wheel speed VFL. Is output. At the same time, the wheel speeds VFR and VFL of the drive wheels detected by the vehicle speed sensors 11 and 12 are averaged by the averaging section 32 to calculate the average wheel speed (VFR + VFL) / 2. The wheel speed output from the high vehicle speed selection unit 31 is multiplied by the variable KG in the weighting unit 33, and the average wheel speed output from the averaging unit 32 is changed by the variable (1
-KG) times and sent to the adder 35 to be added to obtain the driving wheel speed VF. The variable KG is a variable that changes according to the centripetal acceleration GY as shown in FIG.
As shown in FIG. 3, the centripetal acceleration GY has a predetermined value (for example,
0.1g, where g is gravitational acceleration) is proportional to centripetal acceleration, and is set to "1" when the acceleration exceeds this value.

Further, the wheel speeds of the driven wheels detected by the wheel speed sensors 13 and 14 are input to the low vehicle speed selection section 36, and the smaller wheel speed is selected. Further, the wheel speed sensor 13,1
The wheel speed of the driven wheels detected in 4 is input to the high vehicle speed selection unit 37, and the larger wheel speed is selected. And
The smaller wheel speed selected by the low vehicle speed tip portion 36 is multiplied by the variable Kr in the weighting portion 38, and the high vehicle speed selection portion is obtained.
The weighting unit 39 multiplies the larger wheel speed selected at 37 by a variable (1-Kr). This variable Kr changes between "1" and "0" according to the centripetal acceleration GY as shown in FIG.

Further, the wheel speeds output from the weighting section 38 and the weighting section 39 are added in an adding section 40 to obtain a driven wheel speed VR, and the driven wheel speed VR is multiplied by (1 + α) in a multiplying section 40 '. The target drive wheel speed VΦ is set.

Then, the drive wheel speed VF output from the adder 35 and the target drive wheel speed VΦ output from the multiplier 40 'are subtracted in the subtractor 41 to obtain the slip amount DVi' (= VF-V).
Φ) is calculated. The slip amount DVi 'is further corrected in the adder 42 according to the centripetal acceleration GY and the rate of change G of the centripetal acceleration GY. That is, the slip correction amount Vg that changes according to the centripetal acceleration GY as shown in FIG. 5 is set in the slip amount correction unit 43, and the centripetal acceleration as shown in FIG. 6 is set in the slip amount correction unit 44. Slip correction amount that changes according to the change rate G of GY
Vd is set. Then, in the addition unit 42, the slip correction amounts VVi and Vg are added to the slip amount DVi ′ output from the subtraction unit 41 to obtain the slip amount DVi.

This sweep amount DVi is, for example, a sampling time T of 15 ms.
Is sent to the calculation unit 45a in the TSn calculation unit 45, and the slip amount DV
i is multiplied by a coefficient KI and integrated to obtain a correction torque TSn ′.
Is required. That is, the correction torque obtained by integrating the slip amount DVi, that is, the integral correction torque TSn ′ is obtained as TSn ′ = ΣKI · DVi (KI is a coefficient that changes according to the slip amount DVi). Then, the integral type correction torque TSn ′ is obtained by driving the drive forests WFR and WFL.
Correction value for the torque that drives the engine 16
Since it is necessary to adjust the control gain in accordance with the change in the characteristics of the power transmission mechanism between the drive wheels and the drive wheels, the coefficient multiplication unit 45b multiplies the respective gears by different coefficients GKi. Then, the corrected integral correction torque TSn corresponding to the shift speed is calculated.

Further, the slip amount DVi is TPn at every sampling time T.
The correction torque TPn ′ proportional to the slip amount DVi is calculated by being sent to the calculation unit 46a of the calculation unit 46. That is, the correction torque proportional to the slip amount DVi, that is, the proportional correction torque TPn ′ is obtained as TPn ′ = DVi · GKp (Kp is a coefficient). The proportional correction torque TPn 'is multiplied by the different coefficient GKp depending on the shift speed in the coefficient multiplying unit 46b for the same reason as the integral correction torque TSn', and the corrected proportional correction torque TPn according to the shift speed is used. Is calculated.

The driven wheel speed VR output from the adder 40 is input to the reference torque calculator 47 as the vehicle body speed VB. Then, the vehicle body acceleration calculation unit 47 in the reference torque calculation unit 47
At a, the acceleration B (GB) of the vehicle body speed is calculated.

Then, the vehicle body acceleration B (GB) calculated by the vehicle body acceleration calculating section 47a is passed through the filter 47b to be the vehicle body acceleration GBF. In this filter 47b, GBF _n-1 which is the output of the previous filter 47b and GB detected this time are used in order to quickly shift to the "2" position state when the acceleration increases.
_n is weighted and averaged to obtain GBF _n (GB _n + GBF _n-1 ) / 2 (1). In addition, when the acceleration decreases with the slip ratio S> S1 (S1 is set to a value slightly smaller than the maximum slip ratio Smax), for example, when shifting from the "2" position to the "3" position, The filter 47b is switched to a slower filter in order to shift later than at the "1" position. That is, as _{GBF n (GB n + 7BF n} -1) / 8 ... (2), a weight is placed on the output of the previous filter 47b.

In addition, when the slip rate S ≦ S1 and the acceleration decreases, that is, “1”
When the acceleration decreases in the region of (4), the filter 47b is switched to a slower filter in order to stay at Smax as much as possible. In other words, the output of the previous filter 47b is weighted as GBF _n (GB _n + 15BF _n-1 ) / 16 (3). As described above, in the filter 47b, the filter 47b is switched in three stages as shown in the above equations (1) to (3) according to the state of acceleration. Then, the vehicle body acceleration GBF is sent to the reference torque calculation unit 47c and the reference torque TG is transmitted.
Is calculated. That is, TG = GBF × W × Re is calculated. Here, W is the vehicle weight and Re is the tire radius.

Then, the reference torque TG and the integral type correction torque TSn
Is subtracted in the subtracting unit 48, and further subtraction with the proportional correction torque TPn is performed in the subtracting unit 49.
In this way, the target torque TΦ is TΦ = TG-TSn-TP
Calculated as n.

Since this target torque TΦ indicates the torque for driving the drive wheels WFR and WFL, it is divided by the total gear ratio between the engine 16 and the drive wheels in the engine torque calculation unit 50,
It is converted to the target engine torque TΦ ′. Then, the lower limit value setting unit 51 that sets the lower limit value Tlim of the engine torque is set.
In FIG. 16 or 17, the lower limit value of the target engine torque TΦ ′ is limited by the lower limit value Tlim that changes according to the elapsed time from the start of traction control or the vehicle body speed VB. Then, the target end torque TΦ 'whose lower limit value of the engine torque is limited by the lower limit value setting unit 51 is the torque / throttle opening conversion unit.
It is sent to 52 and the opening Θs of the sub-throttle valve for generating the target endon torque TΦ ′ is obtained. Then, by adjusting the opening degree Θs of the sub-throttle valve, the output torque of the engine becomes the target engine torque TΘ ′.
It is controlled as in.

Further, the wheel velocities VRR and VRL of the driven wheels are calculated by the centripetal acceleration calculation unit 53.
The centripetal acceleration GY ′ is sent to determine the turning degree.
Is required. This centripetal acceleration GY 'is the centripetal acceleration correction unit.
54, the centripetal acceleration GY ′ is corrected according to the vehicle speed.

That is, GY = Kv · GY ′, and the coefficient Kv is shown in FIGS.
As shown in FIG. 12, the centripetal acceleration GY is corrected according to the vehicle speed by changing Kv according to the vehicle speed.

By the way, from the vehicle speed VFR of the driving forest, the high vehicle speed selection section
The wheel speed of the 37-output driven wheel having the larger value is subtracted by the subtraction unit 55. Further, the subtracting unit 56 subtracts the wheel speed of the driven wheel having the larger value from the high vehicle speed selecting unit 37 output from the driving wheel wheel speed VFL.

The output of the subtraction unit 55 is multiplied by KB in the multiplication unit 57 (0 <KB
The output of the subtraction unit 56 is multiplied by (1-KB) in the multiplication unit 58 and then added in the addition unit 59 to obtain the slip amount DVFR of the right drive wheel. At the same time, the output of the subtracting unit 56 is multiplied by KB in the multiplying unit 60, the output of the subtracting unit 55 is multiplied by (1-KB) in the multiplying unit 61, and then added in the adding unit 62 to obtain the left driving wheel. The slip amount is DVFL. As shown in FIG. 13, the variable KB changes according to the elapsed time from the start of the control of the traction control, and is set to "0.5" at the start of the control of the traction control, and becomes "0.8" as the control of the traction control progresses. Is set to approach. For example, when KB is set to "0.8", when one of the driving wheels slips, the other driving wheel recognizes that the slip occurs by 20% of the one driving wheel and performs the brake control. I have to. this is,
If the brakes on the left and right drive wheels are made completely independent, when only one drive wheel is braked and rotation is reduced, the drive wheel on the opposite side will slip due to the action of the diff and the brake will be applied, and this operation will be repeated. This is because it is not preferable. The slip amount DVFR of the right drive wheel is differentiated in a differentiator 63 to calculate its temporal change amount, that is, the slip acceleration GFR, and the slip amount DVFL of the left drive wheel is differentiated in a differentiator 64 to obtain its time. The dynamic change amount, that is, the slip acceleration GFL is calculated. And
The slip acceleration GFR is the brake fluid pressure change amount (ΔP).
It is sent to the calculation unit 65 and GFR (GFL) -ΔP shown in FIG.
By referring to the conversion map, the change amount ΔP of the brake fluid pressure for suppressing the slip acceleration GFR is obtained. Also,
Similarly, the slip acceleration GFL is the brake fluid pressure change amount (Δ
P) It is sent to the calculation unit 66, and GFR (GFL) -shown in FIG.
By referring to the ΔP conversion map, the change amount ΔP of the brake fluid pressure for suppressing the slip acceleration GFL is obtained.

In FIG. 14, when the brake is applied at the time of turning, the inner wheel side at the time of turning is indicated by a broken line a in order to strengthen the braking of the drive wheels on the inner wheel side.

Next, the operation of the vehicle acceleration slip prevention device according to the embodiment of the present invention configured as described above will be described. In FIGS. 1 and 2, the wheel speed sensors 13 and 14 are shown.
The wheel speeds of the driven wheels (rear wheels) output from are input to the high vehicle speed selection unit 36, the low vehicle speed selection unit 37, and the centripetal acceleration calculation unit 53. The low vehicle speed selection unit 36 selects the smaller wheel speed of the left and right driven wheels, and the high speed selection unit 37 selects the larger wheel speed of the left and right driven wheels. During normal straight running, when the wheel speeds of the left and right driven wheels are the same, the same wheel speed is selected from the low vehicle speed selection unit 36 and the high vehicle speed selection unit 37. Further, in the centripetal acceleration calculation unit 53, the wheel speeds of the left and right driven wheels are input, and the turning degree when the vehicle is turning from the wheel speeds of the left and right driven wheels, that is, how sharp a turn is made. This degree is calculated.

Hereinafter, what kind of centripetal acceleration is calculated by the centripetal acceleration calculation unit 53 will be described. Since the rear wheels of the front-wheel drive vehicle are the driven wheels, the vehicle speed at that position can be detected by the wheel speed sensor regardless of the slip caused by driving, and therefore Ackermann geometry can be used. That is, in the steady turn, the centripetal acceleration GY ′ is calculated as GY ′ = v ² / r (4) (v = vehicle speed, r = turn radius).

For example, when the vehicle is turning to the right as shown in FIG. 16, the turning center is Mo, the turning center Mo is the inner wheel side (the distance to WRR is r1, the tread is Δr,
Inner wheel side (WRL wheel speed is v1 and outer wheel side wheel speed is
v2.

v2 / v1 = (Δr + r1) (5)

Then, the above equation (5) is modified to be 1 / r1 = (v2-v1) / Δr · v1 (6). Then, the centripetal acceleration GY ′ based on the inner ring side
Is calculated as GY ′ = v1 ² / r1 = v1 ² · (v2-v1) / Δr · v1 = v1 · (v2-v1) ′ / Δr (7).

That is, the centripetal acceleration GY 'is calculated by the equation (7). By the way, since the wheel speed v1 on the inner wheel side is smaller than the wheel speed v2 on the outer wheel side during turning, the centripetal acceleration GY ′ is calculated using the wheel speed v1 on the inner wheel side.
Y'is calculated smaller than the actual value. Therefore, the weighting unit 3
The coefficient KG multiplied by 3 has a smaller value as the centripetal acceleration GY 'is estimated to be smaller. Therefore, since the driving wheel speed VF is estimated to be small, the slip amount DV '(VF-V
Φ) is also underestimated. As a result, the target torque T
Since Φ is largely estimated and the target engine torque is largely estimated, sufficient driving force is applied even during turning.

By the way, in the case of extremely low speed, as shown in FIG.
The distance from the inner wheel side to the center of turning M0 is r1, but in vehicles that understeer as speed increases,
The center of turning turns to M, and the distance is r (r> r1). Even when the speed is increased in this way, the centripetal acceleration GY ′ calculated based on the above equation (7) is calculated as a value larger than the actual value because the turning radius is calculated as r1. Therefore, the centripetal acceleration GY ′ calculated by the centripetal acceleration calculation unit 53 is sent to the centripetal acceleration correction unit 54 so that the centripetal acceleration GY becomes small at high speed.
The centripetal acceleration GY 'is multiplied by the coefficient Kv in FIG. This variable Kv is set to decrease according to the vehicle speed,
It may be set as shown in FIG. 8 or FIG. In this way, the centripetal acceleration GY corrected by the centripetal acceleration correction unit 54 is output.

On the other hand, as the speed increases, oversteering (r <
r1) In the vehicle, the centripetal-acceleration correction unit 54 performs a correction that is completely opposite to the above-described understeering vehicle. That is, any one of the variables Kv in FIG. 10 to FIG. 12 is used to correct the centripetal acceleration GY ′ calculated by the centripetal acceleration calculation unit 53 as the vehicle speed increases.

By the way, the smaller wheel speed selected by the low vehicle speed selection unit 36 is multiplied by a variable Kr in the weighting unit 38 as shown in FIG. 4, and the high wheel speed selected by the high vehicle speed selection unit 37 is weighted by the weighting unit. At 39 is multiplied by the variable (1-Kr). The variable Kr is set to "1" at the time of turning such that the centripetal acceleration GY becomes larger than 0.9 g, and the centripetal acceleration GY becomes
When it is less than 0.4g, it is set to "0".

Therefore, for turning in which the centripetal acceleration GY is larger than 0.9 g, the wheel speed of the low vehicle speed among the driven wheels output from the low vehicle speed selection unit 36, that is, the wheel speed on the inner wheel side during steering is selected. To be done. Then, the weighting units 38 and 39
The wheel speed output from the addition section 40 is added to obtain a driven wheel speed VR, and the driven wheel speed VR is multiplied by (1 + α) in the multiplication section 40 'to obtain the target drive wheel speed VΦ.
It is said that

Also, after the wheel speed of the larger one of the wheel speeds of the drive forest is selected by the high vehicle speed selection unit 31, the weighting unit 33 multiplies it by the variable KG as shown in FIG. Further, the average vehicle speed (VFR + V) of the drive wheels calculated by the averaging unit 32.
FL) / 2 is multiplied by (1-KG) in the weighting unit 34,
The output of the weighting section 33 and the addition section 35 add up to obtain the drive wheel speed VF. Therefore, when the centripetal acceleration GY is, for example, 0.1 g or more, KG = 1, so that the wheel speed of the larger drive wheel of the two drive wheels output from the high vehicle speed selection unit 31 is output. Become. In other words, when the turning degree of the vehicle is increased and the centripetal acceleration GY is, for example, 0.9 g or more, “KG = Kr = 1” is established, so that the driving wheel side changes the wheel speed of the outer wheel side, which has a higher wheel speed, to the driving wheel side. Speed VF
On the driven wheel side, the wheel speed on the inner wheel side where the wheel speed is small is set as the driven wheel speed VR and is set as the sweep amount DVi ′ (= VF−VΦ) calculated by the subtraction unit 41, so the slip amount DVi ′ is It is greatly estimated. Therefore, since the target torque TΦH is underestimated, the output of the engine is reduced, the slip ratio S is reduced, and the lateral force A can be increased as shown in FIG. You can increase the force and make a safe turn.

In the slip amount correcting unit 43, the slip amount correcting unit 43 adds the slip correcting amount Vg as shown in FIG. 5 only when the turning occurs when the centripetal acceleration GY is generated.
At 44, the slip amount Vd as shown in FIG. 6 is added. For example, assuming that a curve turns at a right angle, the centripetal acceleration GY and its temporal change rate G have positive values in the first half of the turn, but the temporal change rate of the centripetal acceleration GY in the latter half of the curve. G has a negative value. Therefore, in the first half of the curve, the slip correction amount VVi (> 0) and the slip correction amount Vd (> 0) shown in FIG.
i, and the slip correction amount Vg in the latter half of the curve
(> 0) and the slip correction amount Vd (<0) are added to obtain the slip amount DVi. Therefore, by estimating the slip amount DVi in the second half of the turn as smaller than the slip amount DVi in the first half of the turn, the engine output is reduced in the first half of the turn to increase the lateral force and improve the turning performance. In the above, the engine output is recovered from the first half to improve the acceleration of the vehicle after the end of turning.

In this way, the corrected slip amount DVi is, for example, 15 m.
It is sent to the TSn calculator 45 at the sampling time T of s. this
In the TSn calculator 45, the slip amount DVi is integrated while being multiplied by the number KI to obtain the correction torque TSn. That is, the correction torque obtained by integrating the slip amount DVi, that is, the integral correction torque TSn, is obtained as TSn = GKi.SIGMA.KI.DVi (KI is a coefficient that changes according to the slip amount DVi).

Further, the slip amount DVi is TPn at every sampling time T.
The correction torque TPn is sent to the calculation unit 46 and is calculated. That is, the correction torque proportional to the slip amount DVi, that is, the proportional correction torque TPn is obtained as TPn = GKp · DVi · Kp (Kp is a coefficient).

Further, the values of the coefficients GKi, GKp used for the calculation in the coefficient multiplying units 45b, 45b are switched to values according to the gear after the shift after a set time from the start of the shift during the shift-up. This takes time from the start of gear shifting until the gear is actually switched and the gear shifting ends, and when shifting up, the above-mentioned coefficients GKi, GKp corresponding to the high gear after gear shifting as well as the start of gear shifting
When using, the values of the correction torques TSn and TPn become values corresponding to the above-mentioned high speed stages, so that the actual torque change is not finished, but the value is smaller than the value before the shift start and the target torque TΦ is increased. This is because slip is induced and control becomes unstable.

The driven wheel speed VR output from the adder 40 is input to the reference torque calculator 47 as the vehicle body speed VB. Then, the vehicle body acceleration calculation unit 47a calculates the vehicle body speed acceleration B (GB). Then, the acceleration GB of the vehicle body speed calculated by the vehicle body acceleration calculation unit 47a is (1) as described in the configuration with the filter 47b.
Any one of the expressions (3) to (3) is applied to stop GBF at an optimum position according to the state of the acceleration GB. Then, the reference torque calculation unit 47c calculates the reference torque TG (GBF × W × Re).

Then, the reference torque TG and the integral type correction torque TSn
Subtraction with and is performed in the subtraction unit 48, and the proportional correction torque TPn is further performed in the subtraction unit 49. In this way, the target torque TΦ is calculated as TΦ = TG−TSn−Tpn.

The target torque TΦ is calculated by the engine torque calculation unit 50.
In, it is converted to the target engine torque TΦ ′. Then, in the lower limit value setting unit 51 that sets the lower limit value Tlim of the engine torque, as shown in FIG. 16 or 17, the lower limit value Tlim that changes according to the elapsed time from the start of traction control or the vehicle body speed VB. Thus, the lower limit of the target engine torque TΦ 'is limited. In other words, even when the reference torque TG cannot be detected well at the start of traction control or at low speed, as shown in FIG. 16 or 17, the torque lower limit value Tl
By setting im to be slightly larger, it is possible to output an engine torque TΦ ′ that is equal to or more than the torque at which slip does not occur, and obtain good acceleration. This is because the engine torque TΦ 'that is equal to or more than the torque at which slip does not occur is output, and even if slip occurs, the brake control suppresses the occurrence of slip.

Then, the target engine torque TΦ ′ having the lower limit value of the engine torque limited by the lower limit value setting unit 51 is sent to the torque / throttle opening degree conversion unit 52 to generate the target engine torque TΦ ′. Opening Θs
Is required. Then, by adjusting the opening degree Θs of the sub-slot valve, the output torque of the engine is controlled to be the target engine torque TΦ ′.

By the way, from the wheel speed VFR of the driving wheels, the high vehicle speed selection section is selected.
The wheel speed of the 37-output driven wheel having the larger value is subtracted by the subtraction unit 55. Further, the subtracting unit 56 subtracts the wheel speed of the driven wheel having the larger value from the high vehicle speed selecting unit 37 output from the driving wheel wheel speed VFL. Therefore, the subtraction unit 55
By estimating the outputs of 56 and 56 to be small, even if a difference in the left and right driven wheel speeds occurs due to the difference in the inner wheels during turning, braking operation due to false detection of slip is prevented, and running stability is improved.

The output of the subtraction unit 55 is multiplied by KB in the multiplication unit 57 (0 <KB
The output of the subtraction unit 56 is multiplied by (1-KB) in the multiplication unit 58 and then added in the addition unit 59 to obtain the slip amount DVFR of the right drive wheel. At the same time, the output of the subtracting unit 56 is multiplied by KB in the multiplying unit 60, the output of the subtracting unit 55 is multiplied by (1-KB) in the multiplying unit 61, and then added in the adding unit 62 to obtain the left driving wheel. The slip amount is DVFL. As shown in FIG. 13, the variable KB changes according to the elapsed time from the start of the control of the traction control, and is set to "0.5" at the start of the control of the traction control, and becomes "0.8" as the control of the traction control progresses. Is set to approach. When the value of KB is set to 0.5 at the start of control, for example, when only one driving wheel slips,
As is clear from the slip amount calculation formula, braking is performed assuming that one of the drive wheels has a slip amount that is half the generated slip amount, but at this time, the other drive wheel actually slips. However, the braking is performed assuming that the same magnitude of slip as that of the one drive wheel has occurred, although the above has not occurred. Therefore, if the value of KB is 0.5, the left and right drive wheels will be uniformly braked.

On the other hand, in the case where only one drive wheel slips as described above, the control responsiveness is lower than that in the case where braking is intensively applied to the drive wheel having the slip. However, in such a case, if only the drive wheels on the slip generation side are suddenly braked from the control start point, in the case of a front wheel drive vehicle, a steering wheel shock will occur as described in the examples of the specification. Moreover, in some cases, the behavior of the vehicle may be unexpected by the driver.

In order to eliminate such a problem, it is necessary to equalize the braking force to the left and right driving wheels even if the responsiveness of the slip control is sacrificed to some extent. Therefore, in the present invention, the value of KB is set to 0.5 at the control start point so that the left and right drive wheels are uniformly braked. However, since KB is increased to a predetermined value over time, it is necessary. By adjusting the time to increase to the above predetermined value accordingly,
It is possible to solve the above-mentioned problems while minimizing the decrease in control responsiveness. The operation will be described when the brake control is continuously performed and KB becomes "0.8". In this case, when the slip occurs in only one drive wheel, the brake control is performed by recognizing that the slip also occurs in 20% of the one drive wheel in the other drive wheel. This is because if the brakes on the left and right drive wheels are made completely independent, the brake will be applied to only one drive wheel and the rotation will decrease. This is because it is repeated, which is not preferable. The slip amount DVFR of the right drive wheel is differentiated in a differentiator 63 to calculate its temporal change amount, that is, the slip acceleration GFR, and the slip amount DVFL of the left drive wheel is differentiated in a differentiator 64 to obtain its time. The dynamic change amount, that is, the slip acceleration GFL is calculated. Then, the slip acceleration GFR is sent to the brake fluid pressure change amount (ΔP) calculation unit 65, and the 14th
By referring to the GFR (GFL) -ΔP conversion map shown in the figure, the change amount ΔP of the brake fluid pressure for suppressing the slip acceleration GFR is obtained. Similarly, the slip acceleration G
FL is sent to the brake fluid pressure change amount (ΔP) calculation unit 66,
By referring to the GFR (GFL) -ΔP conversion map shown in FIG. 14, the change amount ΔP of the brake fluid pressure for suppressing the slip acceleration GFL is obtained.

In FIG. 14, when the brake is applied at the time of turning, the inner wheel side at the time of turning is indicated by a broken line a in order to strengthen the braking of the drive wheels on the inner wheel side. In this way, when the vehicle is turning, the load is moved to the outer wheel side and the inner wheel side is more likely to slip. By making the change amount ΔP of the brake fluid pressure larger on the inner wheel side than on the outer wheel side, At times, it is possible to prevent the inner ring side from slipping.

In the above embodiment, the coefficient GKi, GKp used in the calculation by the coefficient multiplying units 45b, 46b is set to a value corresponding to the gear after the gear shift after the set time has elapsed from the start of the gear shift during the upshift. However, the above switching at the time of shift up may be performed at the end of color change, and the above switching at the time of shift down may be performed at the start of gear shift. In this way, the target engine torque at the time of shift up and at the time of shift down is also good. In this way, the target engine torque TΦ 'during upshift and downshift is suppressed to a small value to prevent the slip from being induced.

Further, in the filter 47b, when the slip ratio S ≦ S1 and the acceleration is decreased, the filter is switched to the formula (3) filter, but the vehicle body acceleration GB is maintained without using the filter of the formula (3). Is also good. Furthermore, when the acceleration is increased, the filter of the above formula (1) is used. However, when the vehicle speed is extremely low (VB <3km / h), GBFn = (GBn + 3GBFn _-1 ) / 4 is used as a slow filter, and when the vehicle speed is normal ( For VB> 3 km / h), a fast filter may be used with GBF = (GBn + GBFn _-1 ) / 2.

Further, in the lower limit value setting unit 51, the lower limit value Tlim may be reduced when the degree of turning increases, that is, when the centripetal acceleration GY increases. In other words, Tlim = Tlim = α · GY (≧ 0) (α is a coefficient) so that even a slight slip is not generated during turning, the lateral force is kept at a large value, and a small slip occurs during turning, Are prevented from deflecting.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a vehicle acceleration slip prevention device capable of reducing an uncomfortable steering wheel shock at the start of control at the split portion.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a vehicle acceleration slip prevention device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing control of the traction controller of FIG. 3 shows the relationship between the centripetal acceleration GY and the variable KG, FIG. 4 shows the relationship between the centripetal acceleration GY and the variable Kr, and FIG. 5 shows the relationship between the centripetal acceleration GY and the slip correction amount Vg. Figures 6 show the rate of change G of the centripetal acceleration over time.
And FIG. 7 to FIG. 12 showing the relationship between the slip correction amount Vd and the slip correction amount Vd.
The figures show the relationship between vehicle speed VB and variable Kv,
FIG. 13 is a diagram showing a change with time of the variable KB from the start of the brake control, and FIG. 14 is a change amount of slip amount GFR (GF
L) and the amount of change in brake fluid pressure ΔP.
FIGS. 5 and 18 show the relationship between the slip ratio S and the friction coefficient μ of the road surface, FIG. 16 shows the Tlim-t characteristic, FIG. 17 shows the Tlim-VB characteristic, and FIG. The figure is a diagram showing a state of the vehicle at the time of turning. 11 to 14 …… Wheel speed sensor, 15 …… Traction controller, 45 …… TSn calculator, 45b, 46b …… Coefficient multiplier, 46
...... TPn calculation unit, 47 ...... Reference torque calculation unit, 53 …… Centripetal acceleration calculation unit, 54 …… Centripetal acceleration correction unit

Claims (1)

[Claims] 1. A braking device capable of individually braking left and right driving wheels of a vehicle, and when a slip occurs on the driving wheels, the braking device is controlled according to the slip state to reduce the slip. In the acceleration slip prevention device for a vehicle, the slip state amount indicating the magnitude of the slip actually occurring in one of the left and right drive wheels and the other drive wheel in the left and right drive wheels are actually The slip detection means for detecting the slip state quantity indicating the magnitude of the generated slip, and the slip state quantity for both drive wheels detected by the slip detection means at the start of control of the braking means The driving wheels are evenly braked by the braking means, and then the slip is detected according to the slip state amount of each driving wheel detected by the slip detecting means. And a traction controller for making the braking force of the braking means for the driving wheel of the larger state larger than the braking force of the braking means for the driving wheel of the smaller slip state. .