JP2536177B2 - Vehicle acceleration slip prevention device - Google Patents

Description

Description of the Invention (Object of the Invention) (Industrial application field) The present invention relates to a device for preventing acceleration slip of a vehicle.

(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)
/ VF] × 100 (percent), VF is the wheel speed of the driving wheel, 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.

Although it is not easy to actually measure the road surface friction coefficient μ, there is a close relationship between the driven wheel acceleration and the road surface friction coefficient μ, for example, as shown in JP-A-60-197434. It has been known. The same thing can be said when the longitudinal acceleration of the vehicle is used instead of the driven wheel acceleration. Therefore,
If the torque transmitted from the drive wheels to the road surface is controlled based on this longitudinal acceleration, it is possible to perform control so that the maximum torque that can be transmitted to the road surface is obtained.

At this time, the actual longitudinal acceleration increases or decreases due to changes in the slip state of the driving wheels due to changes in the driving force, so even if the longitudinal acceleration corresponding to the shaded area in FIG. 18 is detected, the shaded area is again detected. There is a possibility that it will change to a longitudinal acceleration that deviates from. Therefore, the detected actual longitudinal acceleration is not used for control as it is, but a filter that outputs the corrected acceleration that changes with a certain delay time using the detected longitudinal acceleration as an input is used for the control. It is possible.

(Problems to be Solved by the Invention) In such a traction control device, since the delay time of the filter is a constant value, the actual longitudinal acceleration input this time is larger than the correction acceleration output last time. Even if there is, on the contrary, the actual longitudinal acceleration is delayed by the same amount as when the actual acceleration is smaller than the corrected acceleration and is output. Therefore, if the actual longitudinal acceleration input this time is larger than the corrected acceleration that was output the previous time, the corrected acceleration corresponding to the actual longitudinal acceleration should be output quickly and the shaded area in Fig. 18 should be displayed as quickly as possible. Although it is desired to shift to the corresponding control, this cannot be done. In addition, if the delay time of the above filter is shortened to prevent such a problem, if the actual longitudinal acceleration input this time is smaller than the corrected acceleration output last time, it would normally correspond to the previous corrected acceleration. Even though the above torque can be transmitted to the road surface, the corrected acceleration corresponding to the longitudinal acceleration this time changes in a short delay time, so it is possible to output only a torque lower than the actual transmittable torque. Become. That is,
Although it is desired to perform control in response to the state where the shaded portion in FIG. 18 is stopped as long as possible, in reality, the area immediately shifts to the area deviated from the shaded portion.

The present invention has been made in view of the above points, and when the longitudinal acceleration actually changes due to the slip state of the driving wheels accompanying the change of the driving torque, the actual longitudinal acceleration input this time and the previous acceleration output. The acceleration delay of the vehicle can be controlled by changing the delay time of the filter according to the magnitude relationship with the correction speed so that the maximum torque that can be transmitted to the road surface or a torque close to it can be obtained as long as possible. To provide a device.

[Structure of the Invention] (Means and Actions for Solving the Problem) The acceleration slip prevention device for a vehicle according to claim 1 is a slip detection means for detecting a slip state amount indicating a slip state in the drive wheels of the vehicle; An acceleration detection unit that repeatedly detects the longitudinal acceleration of the vehicle, and a longitudinal acceleration that is repeatedly detected by the acceleration detection unit are input and a corrected acceleration that changes with a preset delay time with respect to the change in the longitudinal acceleration is output. , Filter means for changing the delay time according to the magnitude relationship between the longitudinal acceleration input this time and the corrected acceleration output last time, and based on the corrected acceleration output by the filter means,
A reference torque calculation means for calculating a reference torque as a drive torque to be transmitted from the drive wheel to the road surface in order to travel at the corrected acceleration, and a slip state of the drive wheel based on a slip state amount detected by the slip detection means. Correction torque calculation means for calculating a correction torque as a torque reduction amount necessary for reducing the torque, and the reference torque added by the reference torque calculation means is corrected by the correction torque calculated by the correction torque calculation means. It is characterized by comprising a correction means for setting the target torque and an output control means for controlling the output of the engine mounted on the vehicle based on the target torque set by the correction means.

In the vehicle acceleration slip prevention device according to claim 2, when the longitudinal acceleration input this time is larger than the corrected acceleration output last time, the filter means according to claim 1 outputs the longitudinal acceleration input this time last time. The delay time is set to a value smaller than that when the correction acceleration is smaller than the calculated correction acceleration.

According to a third aspect of the present invention, in the vehicle acceleration slip prevention device, the filter means according to the first aspect, when the longitudinal acceleration input this time is smaller than the correction acceleration output last time,
The delay time is set to a larger value when the engine output is controlled by the output control means than when the engine output is not controlled by the output control means.

In claim 1, when the longitudinal acceleration changes, the filter means outputs a corrected acceleration that changes with a preset delay time, and delays according to the magnitude relationship between the longitudinal acceleration input this time and the corrected acceleration output last time. I try to change the time. Then, the reference torque calculating means calculates the reference torque for traveling at the corrected acceleration based on the corrected acceleration output from the filter means. Further, the correction torque calculation means calculates a correction torque as a torque reduction amount necessary for reducing the slip state based on the slip state amount detected by the slip detection means. Then, the reference torque is corrected by the correction torque to set the target torque, and the engine output is controlled based on the target torque.

In claim 2, when the longitudinal acceleration input this time is larger than the correction acceleration output last time, the filter means of claim 1 is more than the correction acceleration output last time input in this time. By setting the delay time to a small value, if the actual longitudinal acceleration input this time is larger than the corrected acceleration output last time, the corrected acceleration corresponding to the actual longitudinal acceleration is output quickly and the road surface is reached as quickly as possible. It is possible to perform control so as to approach the maximum torque that can be transmitted to. On the other hand, if the actual longitudinal acceleration input this time is smaller than the corrected acceleration output last time, the delay time is increased to stop the control corresponding to the previous corrected acceleration as long as possible, and the torque actually transmitted to the road surface. It is possible to suppress the decrease in the maximum torque that can be transmitted to the road surface.

In claim 3, the filter means according to claim 1,
When the longitudinal acceleration input this time is smaller than the correction acceleration output last time, when the engine output is controlled by the output control means rather than when the engine output is not controlled by the output control means. By setting a large value for the delay time, even if the engine output is excessively controlled and the longitudinal acceleration sharply decreases, the reduction of the correction acceleration is suppressed by the filter means having a larger delay time. The sudden decrease in engine output due to the decrease in acceleration is eliminated, and the decrease in acceleration is suppressed.

(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,
WFL indicates a front left wheel, WRR indicates a rear right wheel, and WRL indicates a 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 (driven wheel) WRR, and 14 is a rear left wheel (secondary wheel). Driving 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 control to prevent the drive wheels from slipping during acceleration. This engine 16 has a main throttle valve whose opening is controlled by an accelerator pedal.
In addition to THm, an auxiliary throttle valve whose opening is controlled by a control signal Θs from the traction controller 15
The driving force of the engine 16 is controlled by controlling the opening degree of the auxiliary throttle valve THs by a control signal from the traction controller 15.

Reference numeral 17 denotes a wheel cylinder for braking the front right wheel WFR, and reference numeral 18 denotes a wheel cylinder for braking the front left wheel WFL. Normally, by operating a brake pedal (not shown) to these wheel cylinders, pressure oil is supplied via a master bag, a master cylinder, etc. (not shown). At the time of traction control operation, pressure oil can be supplied from another path described below. The pressure oil is supplied to the wheel cylinder 17 from the hydraulic pressure source 19 through the inlet valve 17i, and the pressure oil is discharged from the wheel cylinder 17 to the reservoir 20 through the outlet valve 17o. The supply of pressure oil from the hydraulic pressure source 19 to the wheel cylinder 18 is performed via an inlet valve 18i, and the discharge of pressure oil from the wheel cylinder 18 to the reservoir 20 is performed via an outlet valve 18o. Then, the inlet valves 17i and 1
8i, the opening / closing control of the outlet valves 17o and 18o is performed by the traction controller 15.

Next, the detailed configuration of the traction controller 15 will be described with reference to FIG. Wheel speed sensor 11
The wheel speeds VFR and VFR of the drive wheels detected in
The FL is sent to a high vehicle speed selecting section (SH) 31, and a higher wheel speed is selected and output from the wheel speed VFR and the wheel speed VFL. 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 in an averaging unit 32 to calculate an average wheel speed (VFR + VFL) / 2. The wheel speed output from the high vehicle speed selection unit 31 is multiplied by a variable KG in the weighting unit 33, and the average wheel speed output from the averaging unit 32 is multiplied by a variable (1-KG) in the weighting unit 34 and added. It is sent to the section 35 and added to obtain the driving wheel speed VF. Note that the variable KG is the third
As shown in the figure, it is a variable that changes according to the centripetal acceleration GY. As shown in FIG. 3, the centripetal acceleration GY is proportional to the centripetal acceleration up to a predetermined value (for example, 0.1 g, where g is the gravitational acceleration), and is set to "1" when it exceeds this value.

The wheel speeds of the driven wheels detected by the wheel speed sensors 13 and 14 are input to the low vehicle speed selection unit 36, and the smaller wheel speed is selected. Further, the wheel speed sensor 1
The wheel speeds of the driven wheels detected in 3 and 14 are input to the high vehicle speed selection unit 37, and the larger wheel speed is selected. Then, the smaller wheel speed selected by the low vehicle speed selector 36 is multiplied by the variable Kr in the weighting unit 38, and the larger wheel speed selected by the high vehicle speed selector 37 is weighted by the weighting unit 39.
Is multiplied by the variable (1-Kr). This variable Kr is the fourth
As shown in the figure, it changes between "1" and "0" according to the centripetal acceleration GY.

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

The drive wheel speed VF output from the adder 35
And the target drive wheel speed VΦ output from the multiplication unit 40 'is subtracted by the subtraction unit 41 to obtain the slip amount DVi' (= VF-
VΦ) is calculated. The slip amount DVi 'is further corrected in the adding section 42 according to the centripetal acceleration GY and the rate of change GY 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. Change rate of GY Slip correction amount Vd that changes according to GY
Is set. Then, in the addition unit 42, the subtraction unit
The slip correction amounts VVi and Vg are added to the slip amount DVi ′ output from 41 to obtain the slip amount DVi.

The slip amount DVi is sent to the calculation unit 45a in the TSn calculation unit 45 at a sampling time T of, for example, 15 ms, and
DVi is integrated while being multiplied by the coefficient KI to obtain the correction torque TS
n 'is required. That is, the correction torque obtained by integrating the slip amount DVi, that is, the correction type correction torque TSn ′ is obtained as TSn ′ = ΣKI · DVi (KI is a coefficient that changes according to the slip amount DVi). The integral type correction torque TSn 'is applied to the drive wheels WFR and WFL.
Correction value for the torque for driving the engine 16
It is necessary to adjust the control gain in accordance with the change in the characteristic of the power transmission mechanism between the power transmission mechanism and the drive wheels due to the switching of the shift speed. Therefore, in the coefficient multiplying unit 45b, different coefficients GKi are multiplied depending on the shift speed. Then, the corrected integrated correction torque TSn corresponding to the gear position is calculated.

The slip amount DVi is T 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 Pn 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 acceleration calculation section in the reference torque calculation section 47
At 47a, the acceleration B (GB) of the vehicle speed is calculated.

Then, the vehicle body acceleration B (GB) calculated by the vehicle body acceleration calculating section 47a is passed through a filter 47b to become the vehicle body acceleration GBF. In this filter 47b, in order to quickly shift to the state of the "2" position when the acceleration increases,
GBF _n-1 which is the output of the previous filter 47b and GB _n detected this time are averaged with the same weighting 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, GBF _n = (GB _n + 7BF _n-1 ) / 8 (2), and the output of the previous filter 47b is weighted.

In addition, when the acceleration decreases when the slip ratio S ≦ S1, that is, when the acceleration decreases in the region of “1”, Sm is reduced as much as possible.
In order to stay at ax, filter 47b is switched to a slower filter. That is, as _{GBF n = (GB n + 15BF} n-1) / 16 ... (3), are highly placed weights the output of the previous filter 47b. 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 the acceleration. Then, the vehicle body acceleration GBF is sent to the reference torque calculation unit 47c, and the reference torque TG 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 correction torque T
Subtraction with Sn is performed in the subtraction unit 48, and further subtraction with 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.

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 and converted into the target engine torque TΦ ′. . And
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 speed VB The lower limit of the target engine torque TΦ 'is limited. 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 ′. The opening Θs of is calculated.
Then, the output torque of the engine is adjusted to the target engine torque TΦ ′ by adjusting the opening Θs of the sub-throttle valve.
Is controlled so that

The wheel speeds VRR and VRL of the driven wheels are calculated by a centripetal acceleration calculation unit.
Sent to 53, centripetal acceleration G to judge turning degree
Y 'is required. The centripetal acceleration GY ′ is sent to the centripetal acceleration correction unit 54, and the centripetal acceleration GY ′ is corrected according to the vehicle speed.

That is, GY = Kv · GY ′, and the coefficient Kv changes according to the vehicle speed as shown in FIGS. 7 to 12, whereby the centripetal acceleration GY is corrected according to the vehicle speed.

By the way, from the wheel speed VFR of the driving wheel, the wheel speed of the larger value in the driven theory of the output of the high vehicle speed selecting section 37 is the subtracting section 55.
Is subtracted. Further, the subtraction unit 56 subtracts the wheel speed of the driven wheel output from the high vehicle speed selection unit 37 having a larger value from the wheel speed VFL of the drive wheel.

The output of the subtractor 55 is multiplied by KB in the multiplier 57 (0 <
KB <1), 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 driving wheel. At the same time,
The output of the subtraction unit 56 is multiplied by KB in the multiplication unit 60, the output of the subtraction unit 55 is multiplied by (1-KB) in the multiplication unit 61, and then added in the addition unit 62 to obtain the slip amount DVFL of the left driving wheel. It is said that 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. It is set to approach. For example, when KB is set to “0.8”, the brake control is performed by recognizing that when one of the driving wheels slips, the other driving wheel slips by 20% of one driving wheel. I have to. This is because if the brakes on the left and right drive wheels are completely independent, when only one of the drive wheels is braked and the rotation is reduced, the action of the differential will cause the drive wheel on the other side to slip and apply the brake. Is repeated, which is not preferable. The slip amount DVFR of the above right drive wheel is the differential part
At 63, the temporal change amount, that is, the slip acceleration GFR is calculated, and at the same time, the slip amount DVFL of the left drive wheel is differentiated at the differentiating section 64 to calculate the temporal change amount, that is, the slip acceleration GFL. It The slip acceleration GFR is calculated based on the amount of change in brake fluid pressure (Δ
P) It is sent to the calculation unit 65, and the GFR (GFL)-
The change amount ΔP of the brake fluid pressure for controlling the slip acceleration GFR is obtained by referring to the ΔP conversion map. Similarly, the slip acceleration GFL is sent to the brake fluid pressure change amount (ΔP) calculation unit 66, and GFR (GF) shown in FIG.
L) -ΔP conversion map is referred to, slip acceleration GF
A change amount ΔP of the brake fluid pressure for suppressing L is obtained.

Incidentally, in FIG. 14, when the brake is applied at the time of turning, in order to strengthen the brake of the inner drive wheel,
The inner wheel side when turning is shown by a broken line a.

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 selecting section 36 selects the smaller wheel speed of the left and right driven wheels, and the high vehicle speed selecting section 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. The degree of whether or not it is calculated is calculated.

Hereinafter, how the centripetal acceleration calculation unit 53 calculates the centripetal acceleration 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 distance from the turning center Mo to the inner wheel side (WRR) is r1, and the tread is Δr.
When the wheel speed on the inner wheel side (WRL) is v1 and the wheel speed on the outer wheel side is v2, v2 / v1 = (Δr + r1) / r1 (5).

Then, the above equation (5) is modified to be 1 / r1 = (v2-v1) / Δr · v1 (6). The centripetal acceleration G is based on the inner ring side.
Y 'is GY' is calculated as ^{= 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 drive wheel speed VF is estimated to be small, the slip amount DV '(VF-V
Φ) is also underestimated. Thereby, the target torque T
Since Φ is largely estimated and the target engine torque is largely estimated, a sufficient driving force is applied even during turning.

By the way, in the case of extremely low speed, as shown in FIG. 19, the distance from the inner wheel side to the center M0 of turning is r1,
In vehicles that understeer as speed increases, the center of turning moves to M and the distance is r (r> r1)
Has become. 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 calculation unit 53
The centripetal acceleration GY ′ calculated in
In step 54, the centripetal acceleration GY 'is multiplied by the coefficient Kv of FIG. 7 so that the centripetal acceleration GY becomes small at high speed. This variable Kv is set to be small according to the vehicle speed, and 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 the reverse of the above-described understeering vehicle. That is, the variable Kv in any of FIGS. 10 to 12
Is used to correct the centripetal acceleration GY ′ calculated by the centripetal acceleration calculating section 53 to increase 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 39. Is multiplied by the variable (1-Kr) at. The variable Kr is set to "1" during turning when the centripetal acceleration GY becomes larger than 0.9 g, for example.
When GY is smaller than 0.4g, it is set to "0".

Therefore, for a turn in which the centripetal acceleration GY is greater than 0.9 g, the low vehicle speed wheel speed of the driven wheels output from the low vehicle speed selection unit 36, that is, the inner wheel speed during steering is selected. You. Then, the weighting unit 38 and
The wheel speed output from 39 is added in the adder 40 to obtain the driven wheel speed VR, and the driven wheel speed VR is multiplied by (1 + α) in the multiplier 40 'to obtain the target drive wheel speed V.
Φ.

In addition, after the wheel speed of the larger one of the wheel speeds of the drive wheels is selected by the high vehicle speed selection section 31, the weighting section 33 multiplies the variable KG by a variable KG as shown in FIG. further,
Average vehicle speed of drive wheels calculated by averaging unit 32 (VFR +
VFL) / 2 is multiplied by (1-KG) in the weighting unit 34, and added by the output of the weighting unit 33 and the adding unit 35 to obtain the driving 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. That is,
The centripetal acceleration GY is, for example, 0.
When the weight is 9 g or more, "KG = Kr = 1", so that the driving wheel side uses the wheel speed of the outer wheel having a higher wheel speed as the driving wheel speed VF, and the driven wheel side uses the wheel speed of the inner wheel having a lower wheel speed. Is the driven wheel speed VR, and the slip amount DVi ′ (= VF−VΦ) calculated by the subtraction unit 41, the slip amount DVi ′ is largely estimated. Therefore, since the target torque TΦ 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 correction unit 43, the slip amount DV ′ is
The slip correction amount Vg as shown in FIG. 5 is added only at the time of turning where the centripetal acceleration GY occurs, and the slip amount Vd as shown in FIG. For example, assuming that a curve turns at a right angle, the centripetal acceleration GY and its temporal change rate Y 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. Y has a negative value. Accordingly, in the first half of the curve, the adder 42 adds the slip correction amount Vg (> 0) shown in FIG.
And slip correction amount Vd (> 0) are added and the slip amount
DVi, and in the latter half of the curve, the slip correction amount Vg
(> 0) and the slip correction amount Vd (<0) are added to obtain the slip amount DVi. Therefore, the slip amount DVi in the latter half of the turn is estimated to be smaller than the slip amount DVi in the first half of the turn. In, the engine output is recovered from the first half to improve the acceleration of the vehicle after the end of the turn.

In this way, the corrected slip amount DVi is, for example, 1
It is sent to the TSn calculation unit 45 at a sampling time T of 5 ms. In the TSn calculator 45, the slip amount DVi is multiplied by the coefficient KI and integrated 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).

The slip amount DVi is T at every sampling time T.
The correction torque TPn is sent to the Pn 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 multiplication units 45b, 46b are switched to values according to the gear after the shift after a set time from the start of the shift at the time of upshifting. This takes time from the start of gear shifting until the gear is actually switched and the gear shifting ends, and at the time of upshifting, the coefficient GKi, GK
When p is used, the values of the correction torques TSn and TPn become values corresponding to the above-mentioned high speed stages, so the actual torque is not finished, but it is smaller than the value before the shift is started, 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 calculating section 47a is filtered by any one of the equations (1) to (3) as described in the configuration by the filter 47b, and the acceleration GB GB according to the state of
I try to stop F at the optimum position.

Then, the reference torque calculation unit 47c calculates the reference torque TG (= GBF × W × Re).

Then, the reference torque TG and the integral correction torque T
Subtraction with Sn is performed in a subtraction unit 48, and the proportional correction torque TPn is further performed in a 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.
At 50, the target engine torque TΦ 'is converted.
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. Due to
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 'which is equal to or higher than the torque at which slip does not occur is output so that the occurrence of slip is controlled by the brake control even when slip occurs.

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-throttle valve, the output torque of the engine is controlled to the target engine torque TΦ ′.

Incidentally, the wheel speed of the driven wheel output from the high vehicle speed selecting unit 37 having a larger value is subtracted from the wheel speed VFR of the driving wheel by the subtracting unit 55.
Is subtracted. Further, the subtraction unit 56 subtracts the wheel speed of the driven wheel output from the high vehicle speed selection unit 37 having a larger value from the wheel speed VFL of the drive wheel. Therefore, the subtraction unit
The outputs of 55 and 56 are underestimated to prevent a brake operation due to erroneous detection of slip and improve running stability even if a difference occurs between left and right driven wheel speeds due to an inner wheel difference during turning.

The output of the subtractor 55 is multiplied by KB in the multiplier 57 (0 <
KB <1), 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 driving wheel. At the same time,
The output of the subtraction unit 56 is multiplied by KB in the multiplication unit 60, the output of the subtraction unit 55 is multiplied by (1-KB) in the multiplication unit 61, and then added in the addition unit 62 to obtain the slip amount DVFL of the left driving wheel. It is said that 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. That is, when the slip of the driving wheels is reduced by the brake, both wheels can be simultaneously braked at the start of the control to reduce an uncomfortable steering wheel shock at the start of braking on the split road, for example. . 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 completely independent, if only one of the drive wheels is braked and the rotation decreases, the differential drive wheel slips due to the action of the differential and the brake is applied. This is because it is not preferable to be repeated. 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) calculating section 65, and the brake fluid for suppressing the slip acceleration GFR is referred to by referring to the GFR (GFL) -ΔP conversion map shown in FIG. Pressure change ΔP
Is required. Similarly, the slip acceleration GFL is sent to the brake fluid pressure change amount (ΔP) calculation unit 66, and the GRF (GFL) -ΔP conversion map shown in FIG. 14 is referred to in order to suppress the slip acceleration GFL. The change amount ΔP of the brake fluid pressure is calculated.

Incidentally, in FIG. 14, when the brake is applied at the time of turning, in order to strengthen the brake of the inner drive wheel,
The inner wheel side when turning is shown by a broken line a. In this way, the load is moved to the outer wheel side during turning, and the inner wheel side easily slips. By making the change amount ΔP of the brake fluid pressure larger than the inner wheel side 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 switched to a value according to the shift stage after the shift after the set time has elapsed from the start of the shift during the shift up. Alternatively, the above-mentioned switching at the time of shift-up may be performed at the end of the shift, and the above-mentioned switching at shift-down may be performed at the start of the shift. In this way, the target engine torque T during upshift and downshift is
Φ ′ is kept small to prevent slipping.

Further, in the filter 47b, the slip ratio S ≦ S1
Then, when the acceleration is reduced, the filter of the formula (3) is switched to, but without using the filter of the formula (3),
The vehicle body acceleration GB may be held. further,
Was to use a filter of equation (1) at the time of acceleration increases, the slow filter as a pole GBF is at low speed _{(VB <3km / h) n} = (GB n + 3GBF n-1) / 4, the normal vehicle speed For (VB> 3km / h), GBF _n = (GB _n + GBF _n-1 ) / 2 may be used as a fast filter.

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.

Next, another embodiment of the present invention will be described. In the other embodiment, only the switching of the filter 47b in FIG. 2 is different from the one embodiment. Hereinafter, the filter 47b will be described in detail.

The filter 47b according to the other embodiment compares GBF _n-1 which is the output of the previous filter 47b with GB _n which is the input of the present filter 47b, and switches the filter according to the comparison result.

(1) When GB _n ≧ GBF _{n-1 In} this case, since the acceleration GB is increasing, a fast filter is used as the filter 47b. For example, the filter represented by the equation (1) of the above-described embodiment is used. As a result, the output of the filter 47b is swiftly followed by the rising of the acceleration GB, so that quick acceleration performance can be obtained.

(2) When GB _n <GBF _n-1 (and the slip amount DVi
≧ 0, or when traction control is not performed) In this case, since the acceleration GB is decreasing, a slow filter is used so as not to be affected by the fall of the acceleration GB. For example, the filter represented by the equation (2) of the above-described embodiment is used.

(3) In the case of GB _{n <GBF n-1} (addition, if the traction control is initiated) In this case, the traction control excessive control by the embodiment described above to protect against the drop in acceleration GB The slowest filter shown in equation (3) is used.

In the case of (3) GB _n <GBF _n-1 , the output of the filter may be held (that is, G
_{BF n = GBF n-1)} . When the output of the filter is held in this way, when GB _n <GBF _{n-1 in} the above item (2), the filter represented by the formula (2) or the formula (3) of the above-described embodiment is used. good.

Next, referring to FIGS. 20 and 21, the filter
The switching of 47b will be described in detail. First, FIG. 20 is a diagram showing the relationship between the slip ratio S and the friction coefficient μ of the road surface. The switching of the filters will be described by taking as an example the case where the slip ratio S shifts by the traction control as shown in the positions to in FIG. Further, when the slip ratio S changes to the position, the acceleration GB and the filter 4
The manner in which the output GBF of 7b changes is shown in FIG.

First, as shown in FIG. 21, when the acceleration GB of the vehicle increases, the acceleration GBF after passing through the filter 47b increases with a delay in the increase of the acceleration GB. Thus, GB _n detected this time for greater GBF _n-1 which is the output of the previous filter 47b, early filter as described above paragraph (1) is used. Then, the acceleration GB continues to increase, and after passing the peak position, the acceleration GB decreases due to the slip of the driving wheels, but the output GBF of the filter 47b is reduced.
Changes after the change in acceleration GB, and therefore continues to increase up to point a. Therefore, up to the point a, a fast filter is used as described in the above item (1). In one embodiment described above, when the acceleration GB passed its peak point (position) and started to decrease, it was switched to the slow filter immediately, but in another embodiment, the acceleration GB is changed to the peak point (position). Even when the reduction is started after passing the (position), the fast filter is used in the period A larger than the output GBF _n-1 of the previous output of the filter 47b. Therefore, in the period A, the drop in the output GBF of the filter 47b due to the decrease in the acceleration GB can be further reduced as compared with the one embodiment.

Next, begin to decrease also output GBF filter 47b beyond the point a, since GB _n detected this time is smaller than the GBF _n-1 which is the output of the previous filter 47b, described above subsection (2) A slow filter is used as described above. And
Acceleration GB decreases, and acceleration GB starts increasing after passing the minimum position, but output GBF of filter 47b continues to decrease to point b due to the use of a slow filter, and at this time, it is larger than acceleration GB. Have. Therefore,
Up to the point b, the filter is used slowly as described in the second term. In the above-described embodiment, the acceleration GB
As soon as the value exceeds its minimum point (position) and starts increasing, it is immediately switched to a faster filter. For this reason, the output GBF of the filter 47b is lowered by switching to a fast filter. Therefore, the acceleration of the vehicle was slow immediately after the acceleration GB passed the minimum point (position) and started to increase. However, in this other embodiment, the slow filter is used in the period B smaller than the output GBF _n-1 of the previous output of the filter 47b even if the acceleration GB starts to increase beyond the minimum point (position). Therefore, in the period B, the filter 47b larger than the acceleration GB is used.
By obtaining the output G BF of the above, the influence due to the fall of the acceleration GB can be further reduced as compared with the above-mentioned embodiment.

Next, after passing point b, the output of the filter 47b starts to increase. Since GB _n detected this time after point b is larger than GB F _n-1 which is the output of the previous filter 47b, a fast filter is used as described in the above item (1). Then, the acceleration GB continues to increase, and the acceleration GB decreases after passing the peak position thereof.
The output GBF of 7b continues to increase up to point c. Therefore, up to the point c, a fast filter is used as described in the above item (1).

Next, past the point c is also the output GBF filter 47b begins to decrease, since GB _n detected this time is smaller than the GBF _n-1 which is the output of the previous filter 47b, described above subsection (2) A slow filter is used as described above.

As described above, according to this other embodiment, the filter 47b
Since the switching to be switched according to the comparison result between GBF _n-1 which is the output of the current detected GB _n and the previous filter 47b, the filter output GB due to decrease of the acceleration GB
F drop can be reduced, and the standard torque can be calculated in μm.
It can be done near the ax. As a result, the acceleration of the vehicle can be further improved.

[Effects of the Invention] As described in detail above, according to the invention of claim 1, when the longitudinal acceleration is actually changed due to the slip state of the driving wheels, the actual longitudinal acceleration input this time and the previous acceleration output last time are output. By changing the delay time of the filter according to the magnitude relationship with the corrected acceleration, it becomes possible to perform control so that the maximum torque that can be transmitted to the road surface or a torque close to it can be obtained for as long as possible, It is possible to ensure the acceleration of the vehicle while appropriately suppressing the slip that occurs.

According to the invention of claim 2, when the actual longitudinal acceleration input this time is larger than the corrected acceleration output last time, the actual longitudinal acceleration input this time is higher than the correction acceleration output last time. By making the delay time smaller than when it is small, if the actual longitudinal acceleration input this time is larger than the corrected acceleration output last time, the corrected acceleration corresponding to the actual longitudinal acceleration will be output quickly to reach the road surface as quickly as possible. It becomes possible to perform control so as to approach the maximum torque that can be transmitted. On the other hand, if the actual longitudinal acceleration input this time is smaller than the corrected acceleration output last time, the delay time is increased to stop the control corresponding to the previous corrected acceleration as long as possible, and the torque actually transmitted to the road surface. It is possible to suppress the decrease in the maximum torque that can be transmitted to the road surface.

Further, according to the invention of claim 3, when the actual longitudinal acceleration input this time is smaller than the correction acceleration output last time, the same control is performed as compared to the case where the engine output is not controlled by the output control means. By increasing the delay time of the filter means when the correction is performed, even if the longitudinal acceleration is drastically reduced due to the excessive control of the engine output, the correction acceleration is increased by the filter means having a larger delay period. Is suppressed, the further rapid decrease in engine output due to the decrease in longitudinal acceleration is eliminated, and it is possible to suppress the decrease in acceleration.

[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. 6 and 6 are diagrams showing the relationship between the rate of change GY in centripetal acceleration and the slip correction amount Vd, and FIGS. 7 to 12 are diagrams showing the relationship between the vehicle body speed VB and the variable Kv, respectively.
FIG. 3 is a diagram showing the change over time of the variable KB from the start of brake control, and FIG. 14 is a diagram showing the relationship between the temporal change amount GFR (GFL) of the slip amount and the brake fluid pressure change amount ΔP, FIG. 18 and 17 show the relationship between the slip ratio S and the friction coefficient μ of the road surface, and FIG. 16 shows the Tlim-t characteristic.
Fig. 19 shows the Tlim-VB characteristics, Fig. 19 shows the state of the vehicle when turning, Fig. 20 shows the relationship between slip ratio S and friction coefficient µ of the road surface, and Fig. 21 shows slip ratio. It is a figure which shows a pattern that acceleration GB and output GBF of filter 47b change, when S changes to a position. 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

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP 62-3137 (JP, A) JP 60-197434 (JP, A) JP 52-198 (JP, B1)

Claims (3)

(57) [Claims] 1. A slip detecting means for detecting a slip state quantity indicating a slip state of a drive wheel of a vehicle, and an acceleration detecting means for repeatedly detecting a longitudinal acceleration of the vehicle.
The longitudinal acceleration repeatedly detected by the acceleration detecting means is input to output a corrected acceleration that changes with a preset delay time with respect to the change in the longitudinal acceleration, and the longitudinal acceleration input this time and the corrected acceleration output last time. Filter means for changing the delay time according to the magnitude relationship between the drive wheel and the drive torque to be transmitted from the drive wheels to the road surface in order to travel at the corrected acceleration based on the corrected acceleration output by the filter means. Reference torque calculation means for calculating a reference torque, and correction torque calculation means for calculating a correction torque as a torque reduction amount necessary for reducing the slip state of the drive wheel based on the slip state amount detected by the slip detection means. When,
A correction unit that corrects the reference torque added by the reference torque calculation unit with the correction torque calculated by the correction torque calculation unit to set a target torque, and the vehicle based on the target torque set by the correction unit. And an output control means for controlling the output of an engine mounted on the vehicle. 2. When the longitudinal acceleration input this time is larger than the corrected acceleration output last time, the filter means sets the delay time more than when the longitudinal acceleration input this time is smaller than the correction acceleration output last time. The acceleration slip prevention device for a vehicle according to claim 1, wherein is set to a small value. 3. When the longitudinal acceleration input this time is smaller than the corrected acceleration output last time, the filter means uses the output control means more than when the engine output is not controlled by the output control means. The acceleration slip prevention device for a vehicle according to claim 1, wherein the delay time is set to a larger value when the engine output is being controlled.