JPH04203333A - Slip control device for vehicle - Google Patents

Abstract

PURPOSE:To prevent a driving wheel from slipping largely by starting slip control when a condition where the time change rate of engine rotational speed is higher than a threshold value with a detected road surface friction coefficient is satisfied. CONSTITUTION:In a control means 8, a rotational speed change rate calculating means 11 calculates the time change rate when engine rotational speed increases based on engine rotational speed detected by an engine rotational speed sensor 10. The threshold value of rotational speed change rate with a road surface friction coefficient detected by a frictional coefficient detecting means 13 is memorized in a rotational speed change rate threshold value memory means 14. A slip control starting means 16 starts slip control when a condition where the detected time change rate of rotational speed is larger than a threshold value with the detected road surface friction coefficient is satisfied. It is thus possible to prevent driving wheels 2FL, 2FR effectively in advance from slipping largely regardless of the amount of the road surface frictional coefficient.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a slip control device for a vehicle.

(Prior art) In order to prevent the drive wheels from slipping due to excessive drive torque and reducing acceleration performance when a vehicle is accelerating, the amount of slip of the drive wheels is detected and the amount of slip of the drive wheels is set to a target value. Traction control that controls the engine output and the application of braking force to the wheels (reducing the engine output or increasing the braking force) is generally known.

Furthermore, in performing the above-mentioned traction control, there is a known proposal to correct the reduction control of the driving force of the driving wheels in accordance with the road surface friction coefficient (see Japanese Patent Laid-Open No. 197434/1983).

(Problem to be Solved by the Invention) By the way, in conventional slip control, a method is adopted in which control is entered after the amount of slip of the driving wheels exceeds a predetermined threshold value, so when the amount of slip mentioned above suddenly becomes large. In such a situation, a large slip may have already occurred in the drive wheels by the time control is started. In that case, even if slip control is started, it will not be possible to bring the slippage to an early end, and the acceleration performance of the vehicle will not be improved.

That is, an object of the present invention is to prevent a situation in which a large slip occurs in the driving wheels.

(Means for Solving the Problems) The present invention solves these problems by first of all, when a large slip occurs in the drive wheels, the rate of increase in engine speed during acceleration of the vehicle is lower than the road surface. Focusing on the fact that the rate of increase is greater than the rate of increase expected from the coefficient of friction, slip control can be started early based on the rate of increase in engine speed and the coefficient of friction on the road surface.

That is, a specific means for this purpose is to detect the engine rotation speed in a slip control device of a vehicle equipped with a slip control means for controlling the drive of the drive wheels so that the amount of slip of the drive wheels with respect to the road surface becomes a target value. an engine rotation speed sensor that detects a road surface friction coefficient, a road surface friction coefficient detection means that detects a road surface friction coefficient, and calculates a time rate of change when the engine rotation speed increases based on the engine rotation speed detected by the engine rotation speed sensor. and a road surface friction coefficient as a factor, in order to start slip control by the slip control means based on the time change rate of the engine speed, the higher the road surface friction coefficient becomes, the higher the threshold value becomes. threshold storage means for storing a threshold value for the rate of change in engine rotational speed set so that the rate of change in engine rotational speed is calculated by the rate of change in engine rotational speed calculated by the rate-of-change calculation means; When a condition is established that the rate of change in engine speed over time is greater than the threshold for the rate of change in engine speed at the road friction coefficient stored in the threshold storage means, based on the road surface friction coefficient, the above-mentioned The present invention is characterized in that it includes slip control starting means for causing the slip control means to start slip control (hereinafter referred to as the first means).

In addition, when a large slip occurs on the drive wheels, we focus on the fact that the rate of change in the amount of slip on the drive wheels when the vehicle accelerates is greater than the rate of change that is permissible in terms of the coefficient of friction on the road surface. This allows slip control to be started early based on the rate of change and the coefficient of road friction.

A specific means for this purpose is a slip control device for a vehicle equipped with a slip control means for controlling the drive of the drive wheels so that the amount of slip of the drive wheels with respect to the road surface becomes a target value, the slip amount of the drive wheels with respect to the road surface. a slip amount detection means for detecting a road surface friction coefficient, a road surface friction coefficient detection means for detecting a road surface friction coefficient, and a time change rate when the slip amount increases based on the slip amount detected by the slip amount detection means. and a slip amount change rate calculation means for starting slip control by the slip control means based on the slip amount change rate, the road surface friction coefficient being set as a factor so that the higher the road surface friction coefficient becomes, the higher the threshold value becomes. threshold value storage means for storing the slip amount change rate threshold value determined, the slip amount change rate calculated by the slip amount change rate calculation means, and the road surface friction coefficient detected by the road surface friction coefficient detection means. ,
Slip control that causes the slip control means to start slip control when a condition that the time change rate of the slip amount is larger than a threshold value of the slip amount change rate at the road surface friction coefficient stored in the threshold storage means is satisfied. (hereinafter, this is referred to as the second means).

Further, a third means for solving the above problem includes a condition that the time rate of change when the engine speed increases in the first means is greater than an engine speed change rate threshold;
The slip control means is configured to cause the slip control means to start slip control when the condition that the time change rate when the slip amount increases in the second means is greater than the slip amount change rate threshold value is also satisfied. be.

(Operation) In the first means, when the time rate of change in the engine speed during acceleration of the vehicle exceeds the engine speed change rate threshold at the road surface friction coefficient at that time, the driving wheel at that time Slip control is started even when the amount of slip is small.

Here, looking at the rate of change over time of the engine speed, that is, the rate of increase, this corresponds to the vehicle body acceleration under the assumption that no slip occurs in the drive wheels. However, when the road surface friction coefficient (friction coefficient between the tires and the road surface) is low, the drive wheels tend to slip, so even if the engine speed increases, the vehicle acceleration does not increase and the In such a situation, a large amount of slip will occur in the drive wheels.

That is, the rate of increase in engine speed has a limit rate of increase that does not cause a large slip in the driving wheels, and this rate of increase differs depending on the road surface friction coefficient. It is something to remember.

Therefore, as in the first means, if the slip control is started when the time rate of change in engine speed exceeds the threshold for the rate of change in engine speed at the current road surface friction coefficient, the amount of control ( By controlling the amount by which the drive torque of the drive wheels is reduced, the slip can be brought to an early end before excessive slip occurs.

Further, since the engine speed change rate threshold value is set differently depending on the road surface friction coefficient, it is possible to perform precise slip control according to the road surface friction coefficient.

In addition, in the second means, when the rate of increase in the actual slip amount of the drive wheels exceeds the slip amount change rate threshold value based on the road surface friction coefficient at that time, the slip control is performed even if the slip amount itself of the drive wheels is small. is started.

In other words, if the rate of change when the amount of slip increases is large, it means that the drive wheels will eventually experience a large slip, and when this rate of increase in the amount of slip exceeds a predetermined threshold, By starting the slip control at the same time, the slip can be quickly brought to an end with a small amount of control before an excessive slip occurs. In this case, when the road surface friction coefficient is high, the slip is unlikely to increase even if the slip amount change rate is large, so the slip amount change rate threshold is set differently depending on the road surface friction coefficient. This makes it possible to perform precise slip control according to the road surface friction coefficient.

Furthermore, in a vehicle equipped with an automatic transmission, the clutch is once disengaged when changing gears when the vehicle is accelerating, causing the engine to suddenly rev up at that moment. In such a case, if slip control initiation control is performed based on the rate of increase in engine speed, slip control will be initiated even when no large slip occurs in the drive wheels, resulting in a reduction in acceleration performance. On the other hand, if the rate of change in the actual amount of slip is checked as in the second method, it is possible to prevent excessive slip from occurring in the drive wheels without performing slip control in vain. It is possible.

Next, in the third means, the condition is that the time rate of change when the engine speed increases is greater than the engine speed change rate threshold, and the time rate of change when the slip amount increases is the slip amount change rate. Since the slip control is started when the condition that the slip control is larger than the threshold value is satisfied, it is possible to cope with vehicles equipped with an automatic transmission and also to cope with road noise.

In other words, the amount of slip increases temporarily when the drive wheels overcome unevenness on the road surface, but if the slip control start control is performed only based on the rate of change in the amount of slip, the slip control will start immediately when the vehicle starts driving on a rough road, for example. This may result in a decrease in drivability on rough roads. On the other hand, if you look at both the rate of increase in engine speed and the rate of change in slip amount, noise caused by uneven road surfaces (fluctuations in slip amount)
If only, slip control is not started and the running performance of the vehicle does not deteriorate.

(Effects of the Invention) Therefore, according to the first means, the engine speed is determined based on the engine speed detected by the engine speed detecting means and the road surface friction coefficient detected by the road surface friction coefficient detecting means. Since the slip control is started when the condition that the time rate of change is larger than the threshold value of the engine speed change rate at the road surface friction coefficient stored in the threshold value storage means is established, the magnitude of the road surface friction coefficient is Regardless, it is possible to efficiently prevent large slips from occurring in the drive wheels.

According to the second means, the time rate of change of the slip amount is stored as a threshold value based on the slip amount of the driving wheels detected by the slip amount detection means and the road surface friction coefficient detected by the road surface friction coefficient detection means. Since the slip control is started when the condition that the slip amount change rate is larger than the threshold value of the slip amount change rate at the road surface friction coefficient stored in the means is satisfied, the slip control is started, regardless of the magnitude of the road surface friction coefficient. It is possible to prevent large slips from occurring in advance and efficiently, and it is also possible to prevent slip control from being started in vain in a vehicle equipped with an automatic transmission.

According to the third means, the condition that the time rate of change when the engine speed increases is greater than the engine speed change rate threshold, and the time rate of change when the slip amount increases is lower than the slip amount change rate threshold. Since the slip control is started when the condition that the value is large is also satisfied,
Slip control will not start due to noise (variations in the amount of slip) caused by uneven road surfaces alone, and while preventing deterioration in driving performance due to this noise, it is possible to avoid causing excessive slip to the drive wheels in vehicles equipped with automatic transmissions. can be prevented from occurring.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the overall configuration of the embodiment.

First, the vehicle has left and right front wheels 2PL and 2PR as driving wheels, and left and right rear wheels 2RL and 2RR as driven wheels. In other words, a V-type 6-cylinder engine 1 is installed at the front of the vehicle.
The torque generated by the engine 1 passes through the automatic transmission 3 and the differential gear 4, and is then transmitted to the left front wheel 2P+ via the left drive shaft 5L, and to the right front wheel 2PR via the right drive shaft 5R. It is now possible to do so.

The vehicle then adjusts the driving wheels 2pL and 2PR so that the amount of slip on the road surface of the driving wheels 2pL and 2PR becomes the target value.
Slip control hand-1 that controls the drive of PL and 2PR
7= Stage 8 is provided, and in order to prevent a large slip from occurring in the drive wheels 2PL and 2PR even when the above-mentioned slip amount is small, the time change rate when the engine speed increases; Drive wheels 2FL, 2PR
Based on the rate of change over time when the amount of slip increases, when these exceed the threshold value for the road surface friction coefficient at that time,
The control means 8 is provided with means for forcibly starting slip control.

In addition, for the above control, the above four wheels 2PL, 2PR
.

A brake sensor 6 that detects whether or not the brakes are applied to 2RL and 2RR, and the four wheels 2PL and 2 mentioned above.
+)R.

2RL, 2RI? Wheel speed sensor 9 PL that detects the wheel speed of.

9PR, 9RL, 9RR, and detection means such as an engine rotation speed sensor 10 for detecting the engine rotation speed are provided.

The control means 8 includes an input interface for receiving signals from various sensors, a microcomputer consisting of a CPU, ROM, and RAM, an output interface, and a drive circuit for driving the igniter and the fuel injection device. , ROM is provided with control programs and various maps or tables necessary for slip control, and RA
M is provided with various memories necessary to execute control, and processes signals from various sensors etc. to generate an ignition timing control signal and a fuel injection limit signal for causing the engine 1 to reduce its output torque. This outputs the following.

Hereinafter, the forced start means for controlling the slip m and the control means 8 will be specifically explained in this order.

<Slip control forced start means> In order to forcibly start the slip control, a time change rate calculation means 11 when the engine speed increases;
Temporal change rate calculation means 12 when the slip amount of the drive wheels 2PL and 2PR increases, and road surface friction coefficient detection means 13
, storage means 14 for storing an engine speed change rate threshold value, storage means 15 for a slip amount change rate threshold value, and slip control starting means] 6 are provided.

1. Engine speed change rate - The time change rate when the engine speed increases, that is, the rate of increase, is calculated based on the engine speed detected by the engine speed sensor 10. That is,
The calculation means 11 calculates the current engine rotation speed N E (
K) and the engine rotational speed N E (K-6) six times before, the increase change amount DNE is determined as the above-mentioned increase rate using the following equation (1).

-Equation (1)- DNE = NE (K) -NE (K-6
) - Slip amount change rate - In order to calculate the slip amount change rate by the slip amount change rate calculation means 12, a vehicle speed detection means 18 and a slip amount detection means 19 are provided.

That is, the vehicle body speed detection means 18 is the wheel speed sensor 9RL.
, 9RR of the wheel speeds VRL and VRR of the left and right driven wheels (rear wheels), whichever is higher, is detected as the vehicle speed Vr. The slip amount detection means 19 calculates the following (2) based on the vehicle speed Vr obtained by the vehicle speed detection means 18 and the wheel speeds VPL and VFR of the driving wheels (front wheels) obtained from the wheel speed sensors 9PL and 9PR. )
The slip of each drive wheel is ff1sP+, according to the formula.

It seeks 9PR.

- Equation (2) - 3FL = V PL - V r S PR = VFR - V r Then, the above-mentioned slip amount change rate calculation means] 2 is the average value of the slips m S FL and S PR of the above-mentioned both driving wheels. Per SAv, the current average slip amount S Av (K
) and the previous average slip amount S Av (K-1), the slip amount change rate DSAv is calculated by the following equation (3).
seek.

-Equation (3)- D S Av= S Av (K) - S Av (K-1
) - Road surface friction coefficient μm The road surface friction coefficient detection means 13 detects the road surface friction coefficient μ based on the vehicle speed Vr and the vehicle acceleration VG.

That is, timer A (1
00m5ec count) and tie 7B (500111
See counter l-) is used. In other words, the vehicle acceleration VC is 100 m when 500 m5ec has passed since the start of the slip control (vehicle acceleration is not large enough).
Based on the change in vehicle body speed Vr (in this example, the faster wheel speed of the rear wheel 2RL, which is the driven wheel, and the wheel speed of 21?I?, unit: km/h) for 1001 Tlsec every 5ec. It is calculated using the following formula (4), and after 500 m5ec has passed (vehicle body acceleration has sufficiently developed), the
Based on the change in vehicle speed Vr during 00m5ec, the following (5)
Obtained by the formula.

-Equation (4)- VC-C old x (V r (k) -V r (k-J
OO) ) - Formula (5) - VC-Gk2X (V r (k) - V r (k-
500) 1 The above Gkl and Gk2 are coefficients. Also, V r (k) is at present, V r (k-1oo) is 100 m5ec ago, and Vr (k-500) is 500 m
These are the vehicle speeds before 5ec.

Then, the road surface friction coefficient μ is determined by three-dimensional interpolation using the following μ table from the vehicle body acceleration VG and vehicle body speed Vr calculated as described above.

Figure 2 shows the flow of the vehicle acceleration calculation and road surface friction coefficient calculation, and if slip control is in progress (CFL-1) and 500 m5ec has not passed since the start of slip control, then 10
Check whether 0rIlsec has elapsed (steps S1 to S
3) o If 100m5ec has passed, please refer to (4) above.
), find the vehicle body acceleration VG according to the formula, and calculate this vehicle body acceleration V
The road surface friction coefficient μ is calculated based on C and the vehicle speed Vr, and then the timer A is reset and the detected vehicle speed Vr is calculated.
is updated to the detected value after 100m5ec (step S4
~S7).

The above updates are 500m5ec, 400m5ac, 3
00tnsea, 200 TQsee, and 100m
Each vehicle speed V r detected 5ec ago is set to 40
0m5ec, 300111Sf3e% 200m5e
cs This is to change to the detected value 100m5ec ago and this time.

Further, when it is determined in step S2 that 500 m5ec has elapsed, it is determined whether or not timer A has elapsed 100 m5ec (step S8). And 1o.

If m5ec has elapsed, calculate the vehicle acceleration VG according to the above equation (5), calculate the road surface friction coefficient μ based on this and the vehicle speed Vr, and then reset timer A and set timer B to 500 m5ec. (steps 89 to 512).

Furthermore, when slip control is not in progress, timers A and B are reset and the road surface friction coefficient μ is set to 3.0 (step Sl, 31B).

- Engine speed change rate threshold - The engine speed change rate threshold storage means 14 stores the engine speed change rate threshold in the control means 8 based on the engine speed change rate DNE over time.
To start slip control by the road friction coefficient μ
and automatic transmission 3 shift ranges (D range, 1st gear range,
2nd speed range) as a factor, this road friction coefficient μ
The engine speed change rate threshold value K is stored such that the higher the value becomes, the higher the threshold value becomes. This threshold value is shown in the following table.

-Slip amount change rate threshold~ The storage means 15 for the slip amount change rate threshold stores the road surface friction coefficient μ as a factor in order to start the slip control by the control means 8 based on the slip amount change rate DSAv. A slip amount change rate threshold value C is stored, which is set so that the higher the road surface friction coefficient μ, the higher the threshold value is. This threshold value C is shown in the following C table.

K-Table - Slip Control Starting Means - The slip control starting means 16 includes a rotational speed change rate determining means 21, a slip amount change rate determining means 22, and an AND circuit 23, as shown in FIG.

The rotational speed change rate determination means 21 determines the engine rotational speed change rate DNE calculated by the rotational speed change rate calculation means 11 described above.
, the road surface friction coefficient μ detected by the friction coefficient detection means 13, the vehicle speed Vr detected by the vehicle speed detection means 18, and the throttle opening THO of the engine 1 detected by the throttle opening detection means 24. When the condition that the engine speed change rate DNE is larger than the road surface friction coefficient μ stored in the engine speed change rate threshold value storage means 14 and the engine speed change rate threshold value in the shift range is established based on . , the first engine flag EFL
(1) is set to 1.

In this case, the shift range is determined by a map (not shown) based on the vehicle speed Vr and the throttle opening THO.

The slip amount change rate determination means 22 determines the slip amount based on the slip amount change rate DSAv calculated by the slip amount change rate calculation means 12 and the road surface friction coefficient μ detected by the friction coefficient detection means 13. Change'$DS
When the condition that Av is larger than the slip amount change rate threshold C at the road surface friction coefficient μ stored in the slip amount change rate threshold storage means 15 is established, the second engine flag EFL (2) is set to 1. That is.

Then, the AND circuit 23 sets the slip flag SFL to 1 when both the first and second engine flags EFL (1) and (2) are 1.

Figure 4 shows the flow of the slip control start control described above, and each wheel speed VPL, VFR, VRL, VRR.
, engine speed NE, and throttle opening THO, and first calculates the road surface friction coefficient μ (steps S21, 522). And engine speed change rate DN
E is larger than the threshold and the slip amount change rate DSAv
When the condition that is larger than the threshold value C is satisfied, slip control is started (steps 823 to 525).

Control means> As shown in FIG. 5, the control means 8 includes a slip determination threshold setting means 32, a slip amount calculation means 33, a slip determination means 34, a control target value setting means 35, and a control level calculation means. Means 36 and engine output control means 37 are provided.

[Setting of slip determination threshold value This slip determination threshold value is for determining whether slip control is required or not, and is determined from the vehicle speed Vr and the road surface friction coefficient μ.

That is, the threshold value is calculated by three-dimensional interpolation from the following threshold value table 1.2.

-Threshold table 1 (for starting) Threshold table 2 (for continuation) The above threshold table 1 is for determining whether to start slip control, and the threshold table 2 is for determining whether to continue slip control. It is for the purpose of

[Slip amount calculation] The slip calculation means 33 is the slip amount detection means 1 described above.
Slip amount SPL of each drive wheel detected by 9, SP
While calculating the average slip amount SAv based on R,
The higher slip amount of both slips ff1sPL and SPR is determined as the maximum slip amount SHi.

[Slip Judgment The co-slip judgment means 34 judges that slip control is necessary when the following equation (6) is satisfied based on the maximum slip amount SHi and the slip judgment threshold value, and sets the slip flag SF.
Let L be 1 - Equation (6) - 8Hi≧Slip Judgment Threshold In this case, the slip judgment threshold is set to a non-control state (CFL-0) by the slip control judgment means 66 described later.
) is determined, the aforementioned threshold table 1 (
When slip control is being determined (CFL-1), the threshold value based on threshold table 2 (for start) is used.
(for continuation) is used.

[Setting of Control Target Value] This control target value T is the value targeted as the slip amount of the front wheels 2PL and 2PR, and is set by the control target value calculating means 3.
5 calculates a control target value by three-dimensional interpolation from the following control target value table based on the vehicle speed Vr and the road surface friction coefficient μ.

Control target value table [Control level calculation] For the control level FC, the deviation EN of the average slip amount SAv from the control target amount T, and the rate of change DE of this deviation.
N, the feedback correction of the previous value FC(K-1) and the initial value correction are added to this, and the value is set in the range of 0 to 15. For this purpose, as shown in FIG. A calculation means 65 is provided.

The deviation calculating means 60 subtracts the control target value T from the average slip amount SAv to obtain the deviation EN.

The deviation change rate calculating means 61 calculates the deviation change rate DEN based on the following equation (7).

-Equation (7)- D E N -E N (K) -E N (K-1)
The basic control level calculating means 62 calculates the basic control level PCB based on the deviation EN and the deviation change rate DEN using the following basic control level table.

The basic control level table feedback correction means 63 determines the current control level F.
The control level F C (K-1) of the previous calculation is added to C (K).

The initial correction amount calculating means 64 is for forcibly increasing the control level from the time when front wheel slip is determined for the first time until this first slip determination is eliminated, and for this purpose, the slip control shown in FIG. determining means 66;
Initial slip control determining means 67 shown in the figure is provided.

In FIG. 7, 68 is an AND circuit that outputs a set signal to the flip-flop 69 when the slip flag 5FL-1 is in a non-braking state, and 70 is an AND circuit that outputs a set signal when FC≦3 and DSAv≦0, 3g. 1, the AND circuit 71 outputs the slip flag 5FL via the counter 72.
=O signal continuously for 1000Illsec,
Alternatively, when the output signal 1 is continuously received from the AND circuit 70 for 500111 seconds via the counter 73, the OR circuit outputs a reset signal to the six flip-flops.
It is a circuit. When the flip-flop 69 receives the set signal, it outputs a control flag CFL-1 (slip control in progress) signal.

In addition, in FIG. 8, 74 is the current control flag CFL.
(K)-1 and the previous control flag CFL(K-1,)
-0, an AND circuit outputs a set signal to the flip-flop 75, 76 is the current slip flag 5FL
(K)-0 and the previous slip flag 5FL (K-1
)-1, this is an AND circuit that outputs a reset signal to the flip-flop 75. Then, the flip-flop 75 receives the set signal and sets the first flag 5TFL=
1 (initial control in progress) signal is output.

The initial correction amount calculation means 64 inputs the initial flag 5TFL signal and the average slip amount change rate DSAv, and calculates the 5TF
When L=1 and DSAv≧0, the initial correction amount (+5) is calculated and output, and when 5TFL-1 and DSAv<0, the first correction is performed! (+2) is calculated and output.

The final control level calculation means 65 adds the above-mentioned initial correction amount to the feedback-corrected control level FC.

[Output Control] Regarding one ignition timing control, as shown in FIG. 9, the retard amount is determined and output according to the control level. In this case, as shown in FIG. 10, the maximum retard amount is limited in a region where the engine speed is high.

- Fuel injection restriction (fuel cut) - Fuel injection is restricted by selecting patterns O to 12 of the next fuel cut table based on the above control level (the higher the level, the higher the pattern is selected). In this case, as shown in FIG. 11, a fuel cut prohibition condition is attached to each control level so that fuel cut is restricted in a region where the engine speed is low. Note that the x in the above table means fuel injection cut.

FIG. 12 shows the flow of the slip control described above.

In other words, the threshold value for determining the start of slip control for transition from a non-control state to slip control is determined by calculating a basic value using a starting basic value table, and setting the threshold value to a relatively high threshold value (
(corresponding to sh in FIG. 12). Therefore, the wheel speed of the driving wheels is high due to disturbance etc. (maximum slip amount S
Even if Hi becomes large), the slip flag SFL will not be set and control will not be started unless the threshold value sh is exceeded.

When the driving wheel speed exceeds the threshold value sh, the slip flag SFL is set, and if the brake is not in operation, the control flag CFL and the initial flag 5TFL are set.

As a result, slip control is started.

Furthermore, even when the wheel speed of the driving wheels does not exceed the threshold sh, the engine speed change rate DNE is greater than the engine speed change rate threshold, and the slip amount change rate DSAv is greater than the slip amount change rate threshold C. If both conditions are satisfied, the slip flag SFL is set and slip control is started in the same way as in the above case.

In slip control, the average slip amount SAv is calculated based on the front wheel speeds VPL and VFR and the vehicle speed Vr, while the control target value T is set based on the vehicle speed Vr and the road surface friction coefficient μ. Then, the control target value T
A basic control level is set based on the deviation EN of the average slip amount SAv from Ignition timing control and fuel injection restriction control are performed.

The initial correction is (+5) until the rate of change of the average slip amount DSAv becomes zero for the first time, and then the initial correction flag 5 is applied.
The time until TFL reaches O is (+2). By this initial correction, the control amount is forcibly increased, and the slip can be brought to an early conclusion.

The initial flag 5TFL becomes 0 when the maximum slip ff1sHi due to the wheel speed of the higher driving wheel becomes equal to or less than the threshold for determining whether to continue the slip control, and at this point the slip control is temporarily stopped. The basic value of this continuation determination threshold (corresponding to 81 in FIG. 12) is calculated using the continuation basic value table, and is set to a relatively low threshold. Therefore, the slip can be reliably brought to an end.

As mentioned above, even if the driving wheel speed does not exceed the threshold value Sh, slip control is started when the engine speed change rate DNE and the slip amount change rate DSAv are large, so even if the driving wheel speed does not exceed the threshold value Sh, slip control is started when the engine speed change rate DNE and the slip amount change rate DSAv are large. This means that the slip can be brought to an early end before excessive slip occurs.

In a vehicle equipped with an automatic transmission, the clutch is once disengaged when changing gears when the vehicle is accelerating, causing the engine to suddenly rev up at that moment. On the other hand, since not only the rate of change in engine speed but also the rate of change in slip amount is checked, slip control is not performed in vain.

In addition, the amount of slip increases temporarily when the drive wheels go over the unevenness of the road surface, but as mentioned above, since we are looking at both the rate of increase in engine speed and the rate of change in the amount of slip, noise (variation in slip amount)
If only, slip control is not started and the running performance of the vehicle does not deteriorate.

Even if the wheel speed of the higher driving wheel becomes equal to or less than the continuation determination threshold Sl, the control flag CFL remains set unless this state continues for one second or more. Then, as the slip control is discontinued, the driving wheel speed increases again and exceeds the continuation determination threshold Sl, the slip flag SFL is set again and the slip control is restarted. In this case, the initial flag 5TFL is not set, and there is no initial correction of the control level FC. Therefore, the control level FC is initially set to the deviation E
Only the basic control level is set based on N and the deviation change rate DEN, and thereafter, the control level FC is set by adding the previous value to the basic control level by feedback correction.

As described above, when the slip converges and the slip flag SFL does not stand for one second or more, the control flag CFL becomes 0 and this series of slip control ends.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall configuration diagram of a slip control device for a vehicle, FIG. 2 is a flow diagram for calculating a coefficient of road friction, FIG.
Figure 5 is a flow diagram of slip control start control, Figure 5 is a configuration diagram of the slip control means, Figure 6 is a configuration diagram of the control level calculation means, Figure 7 is a configuration diagram of the slip control determination means, and Figure 8 is the configuration diagram of the slip control means. A configuration diagram of the slip control determination means, FIG. 9 is a characteristic diagram showing the relationship between the control level and the ignition timing retard amount, and FIG.
FIG. 0 is a characteristic diagram showing the restriction of the ignition timing retard amount depending on the engine speed, FIG. 11 is a characteristic diagram showing the fuel cut restriction area depending on the engine speed, and FIG. 12 is a time chart of slip control. 1...Engine 2PL, 2PI? ...Front wheel (drive wheel) 2R
L, 2RR... Rear wheel (driven wheel) 8...
... Control means 9PL to 9RR ... Wheel speed sensor 10 ...
...Engine speed sensor 11...Rotational speed change rate calculation means 12...Slip amount change rate calculation means 13....Friction coefficient detection means 14... Rotation speed change rate threshold storage means 15...
... Slip amount change rate threshold storage means 16 ... Slip control starting means 18 ...
・Vehicle speed detection means-44 = Whale 1-> 9

Claims (3)

[Claims] (1) A slip control device for a vehicle comprising a slip control means for controlling the driving of the drive wheels so that the amount of slip of the drive wheels with respect to the road surface becomes a target value, an engine rotation speed sensor that detects the engine rotation speed; road surface friction coefficient detection means for detecting a road surface friction coefficient; and an engine speed change rate calculation for calculating a time rate of change when the engine speed increases based on the engine speed detected by the engine speed sensor. and an engine set such that the higher the road friction coefficient becomes, the higher the threshold value becomes, using a road surface friction coefficient as a factor, in order to start slip control by the slip control means based on the time rate of change of the engine speed. Threshold storage means for storing a rotational speed change rate threshold; based on the time rate of change in engine rotational speed calculated by the engine rotational speed change rate calculation means; and the road surface friction coefficient detected by the road surface friction coefficient detection means. and when a condition is established that the rate of change in engine speed over time is greater than a threshold value for the rate of change in engine speed at the road surface friction coefficient stored in the threshold storage means, the slip control means performs slip control. 1. A slip control device for a vehicle, comprising: means for starting slip control. (2) In a slip control device for a vehicle equipped with a slip control means for controlling the drive of the drive wheels so that the amount of slip of the drive wheels with respect to the road surface becomes a target value, a slip amount that detects the amount of slip of the drive wheels with respect to the road surface. a detection means; a road surface friction coefficient detection means for detecting a road surface friction coefficient; and a slip amount change rate for calculating a time change rate at which the slip amount increases based on the slip amount detected by the slip amount detection means. a calculation means; and a slip amount change set such that the higher the road surface friction coefficient becomes, the higher the threshold value becomes, using the road surface friction coefficient as a factor, in order to start slip control by the slip control means based on the slip amount change rate. A slip amount change rate is determined based on a threshold storage means for storing a rate threshold value, a slip amount change rate calculated by the slip amount change rate calculation means, and a road surface friction coefficient detected by the road surface friction coefficient detection means. and slip control starting means for causing the slip control means to start slip control when a condition that the rate of change in slip amount at the road surface friction coefficient is greater than a threshold value stored in the threshold value storage means is satisfied. A vehicle slip control device characterized by: (3) A slip control device for a vehicle comprising a slip control means for controlling the drive of the drive wheels so that the amount of slip of the drive wheels with respect to the road surface becomes a target value, an engine rotation speed sensor that detects the engine rotation speed; The engine rotation speed is determined based on the engine rotation speed detected by the slip amount detection means for detecting the amount of slip of the driving wheels with respect to the road surface, the road surface friction coefficient detection means for detecting the road surface friction coefficient, and the engine rotation speed sensor. An engine speed change rate calculation means for calculating a time change rate when the engine speed increases, and a slip amount for calculating a time change rate when the slip amount increases based on the slip amount detected by the slip amount detection means. a rate of change calculation means, and a threshold value set such that the higher the road friction coefficient becomes, the higher the road friction coefficient becomes a factor, in order to start slip control by the slip control means based on the time rate of change of the engine speed. a threshold storage means for storing a threshold value of the engine rotational speed change rate, and a road surface friction coefficient as a factor for starting slip control by the slip control means based on the slip change rate; threshold storage means for storing a slip amount change rate threshold set to be a high threshold; a time rate of change in engine speed calculated by the engine speed change rate calculation means; and a road surface friction coefficient detection means. Based on the detected road surface friction coefficient, a condition is established that the time rate of change in the engine speed is larger than a threshold value for the rate of change in engine speed at the road surface friction coefficient stored in the threshold storage means, and Based on the slip amount change rate calculated by the slip amount change rate calculation means and the road surface friction coefficient detected by the road surface friction coefficient detection means, the slip amount change rate is stored in the threshold storage means. A slip control device for a vehicle, comprising slip control starting means for causing the slip control means to start slip control when a condition that the slip amount change rate in the road surface friction coefficient is larger than a threshold value is satisfied. .