JPS6331864A - Slip controller for automobile - Google Patents

Abstract

PURPOSE:To make the torque given to driving wheels quickly convergeable toward the desired value, by installing an altering device which alters a speed of response to the direction of increasing the torque given to the driving wheels so as to make it smaller as compared with the time of being hard to slip when a road surface is liable to slip. CONSTITUTION:There is provided with a torque regulating device A which regulates the torque given to driving wheels by means of generated torque regulation by control over a throttle valve of an engine and braking force regulation by a brake. And also, there is provided with a slip detecting device B detecting a slip state to a road surface of the driving wheels, and the torque regulating device A is controlled by a slip controlling device C so as to cause the detected driving wheel slip to become the specified desire value. In addition, there is provided with a road state detecting device D which detects slipperiness of the road surface, and according to the output, a speed of response in the direction of increasing the torque given to the driving wheels is set so as it make it smaller as compared with the time of being hard to slip when the road surface is liable to slip by a response speed altering device E.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides an automobile slip control system that prevents excessive slip of the drive wheels relative to the road surface by controlling the torque applied to the drive wheels. It concerns control attachment.

(Prior Art) Preventing the drive wheels from slipping excessively on the road surface is effective in effectively obtaining the propulsion force of the vehicle and in terms of safety by preventing spin. In order to prevent excessive slippage of the drive wheels, it is sufficient to reduce the torque applied to the drive wheels, which causes the slippage.

A conventional slip control of this type is disclosed in Japanese Patent Laid-Open No. 16948/1983. The technology disclosed in this publication reduces the torque applied to the drive wheels by applying braking force to the drive wheels using a brake,
This is done by utilizing the reduction in torque generated by the engine itself. More specifically, when the slip of the drive wheels is small, only the brakes are applied to the drive wheels, while when the slip of the drive wheels becomes large, in addition to the braking of the drive wheels, the torque generated by the engine is reduced. It is designed to let you do so. In other words, braking of the drive wheels by the brake is mainly used, and the torque generated by the engine is reduced in an auxiliary manner.

In the above-mentioned publication, cornering is mentioned as a case where slip control of the drive wheels is performed. That is,
While the load on the inner drive wheel in the turning direction is smaller, the torque applied to the outer drive wheel increases due to the effect of the differential gearing, and its slip increases, so it is sometimes necessary to perform slip control on this outer drive wheel. It is shown. It is also disclosed that the slip control of the outer drive wheels is performed based on the inner drive wheels with smaller slip (so-called select low).

(Problems to be Solved by the Invention) When the slip of the driving wheels is to be converged to a predetermined target value, one problem is how to set the response speed. That is, in order to quickly converge the slip of the drive wheels to a predetermined target value, it is sufficient to increase the rate of change of the applied torque, that is, the response speed of the control. However, when this response speed is increased, there is a risk of re-slip, especially when the torque applied to the drive wheels is increased, and the problem is how to deal with this problem.

To explain this point in detail, assuming that the response speed is set to be fast enough to quickly reduce excessive slip, if this applied torque is increased, the response speed is too fast and the size of the slip is at the target level. It is conceivable that the value may be exceeded (overshoot), and the degree to which the slip of the drive wheels increases due to increasing the applied torque differs depending on the degree of slipperiness of the road surface.

The present invention was made in consideration of the above circumstances, and
By optimally setting the response speed of the slip control system,
An object of the present invention is to provide a slip control device for an automobile, which prevents large slips from occurring again during slip control while converging the size of a drive wheel to a target value as quickly as possible.

(Means and operations for solving the problem) In order to achieve the above-mentioned object, in the present invention, the control in the direction of increasing the slip, that is, the response speed in the direction of increasing the torque applied to the drive wheels, When the road surface is slippery, it is set (changed) so that it is smaller than when it is difficult to slip. With this configuration, it is possible to speed up the convergence toward the target value while reliably preventing large slips from occurring again depending on the degree of slipperiness of the road surface. Specifically, the second? -As shown in the figure, in an automobile slip control system that prevents excessive slip of the drive wheels against the road surface by controlling the torque applied to the drive wheels, the torque applied to the drive wheels is adjusted. a slip detection means for detecting a slip state of the drive wheels relative to the road surface; and a control means for controlling the torque adjustment means so that the slip of the drive wheels reaches a predetermined target value in response to an output from the slip detection means. a road surface condition detection means for detecting the slipperiness of the road surface; and a road surface condition detection means for detecting the slipperiness of the road surface; and a response speed changing means for setting the response speed to become smaller.

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

In FIG. 1, a car 1 has left and right front wheels 2 that serve as driving wheels.
．． 3 and 1. It is equipped with four wheels, with the left and right rear wheels serving as driving wheels. An engine 6 as a power source is mounted on the front of the automobile 1, and the torque generated by the engine 6 passes through a clutch 7, a transmission 8, and a differential gear 9, and then is transmitted to left and right drive shafts 10 and 11. The power is transmitted to the left and right front wheels 2.3 as driving wheels.

In this way, automobiles are FF type (front engine
It is said to be a front drive).

The engine 6 as a power source has its intake passage 12
Load control, that is, control of generated torque is performed by a throttle valve 13 disposed in the engine. More specifically, the engine 6 is a gasoline engine, and the generated torque changes depending on the change in the intake air amount, and the intake air amount is adjusted by the throttle valve 13. The throttle valve 13 is electromagnetically controlled to open and close by a throttle actuator 14. It should be noted that the throttle actuator 14 may be constituted by an appropriate device such as a DC motor, a step motor, or one driven by fluid pressure such as oil pressure and electromagnetically controlled.

Each wheel 2-5 has a brake 21, 22, 23, respectively.
Alternatively, 24 are provided, and each of the brakes 21 to 24 is a disc brake. As is known, this disc brake includes a disc 25 that rotates together with the wheel and a caliper 26. This caliper 2
6 holds the brake pad and is provided with a wheel cylinder, and the brake pad is moved to the disc 25 with a force according to the magnitude of the brake fluid pressure supplied to the wheel cylinder.
Braking force is generated by pressing against the

The mask cylinder 27 as a brake fluid pressure generation source is 2
It is of a tandem type having two discharge ports 27a and 27b. The brake pipe 28 extending from the discharge port 27a is branched into two branch pipes 28a and 28b in the middle, and the branch pipe 28a is connected to the right front wheel brake 22 (wheel cylinder).
The branch pipe 28b is connected to the left rear wheel brake 23. Further, the brake pipe 29 extending from the discharge port 27b is branched into two branch pipes 29a and 29b in the middle, the branch pipe 29a is connected to the brake 21 for the left front wheel, and the branch pipe 29b is connected to the brake 24 for the right rear wheel. It is connected to the. In this way, the brake piping system is of the so-called two-system X type. An electromagnetic hydraulic pressure control valve 30 or 31 as a braking force adjusting means is connected to branch pipes 28a and 29a for the front wheel brakes 21 and 22, which are drive wheels. Of course, the brake fluid pressure generated in the mask cylinder 27 depends on the amount (depression force) of the brake pedal 32 by the driver.

Brake Hydraulic Pressure Control Circuit As shown in FIG. 2, each of the hydraulic pressure control valves 30, 31 has a cylinder 41 and a piston 42 that is slidably inserted into the cylinder 41. The piston 42 defines the inside of the cylinder 41 into a variable volume chamber 43 and a control chamber 44 . This variable volume chamber 43 is
It serves as a passageway for brake fluid pressure from the mask cylinder 27 to the brake 21 (22). Therefore, by adjusting the displacement position of the piston 42, the volume of the variable volume chamber 43 is changed, and the brake 21 (22)
This means that the brake fluid pressure can be increased, decreased or maintained.

The piston 42 is constantly urged by a return spring 45 in a direction in which the volume of the variable volume chamber 43 increases. Further, a check valve 46 is integrated into the piston 42. This check/help 46 closes the inlet side to the variable volume chamber 43 when the piston 42 is displaced in a direction to reduce the volume of the variable volume chamber 43. As a result, the brake hydraulic pressure generated in the variable volume chamber 43 acts only on the brake 21 (22) side and does not act on the brake 23, 24 of the rear wheel 4.5 as a driven wheel. It has become.

The displacement position of the piston 42 is adjusted by adjusting the control hydraulic pressure to the control chamber 44. To explain this point in detail, the supply pipe 48 extending from the reservoir 47 is branched into two branches in the middle, and one branch pipe 48R is connected to the valve 30.
The other branch pipe 48L is connected to the control chamber 44 of the valve 31. A pump 49 and a relief valve 50 are connected to the supply pipe 48, and a supply valve SV3 (SV2) consisting of an electromagnetic on-off valve is connected to the branch pipe 48L (48R). Each control chamber 44 is further connected to the reservoir 47 via a discharge pipe 51R or 51L, and a discharge valve SV4 (SVI) consisting of an electromagnetic on-off valve is connected to the discharge pipe 51L (51R).

During braking (slip control) using this hydraulic pressure control valve 30 (31), the check valve 46 basically prevents the brake pedal 32 from being applied. However, when the brake fluid pressure generated by the fluid pressure control valve 30 (31) is small (
For example, during depressurization), the brake is applied by operating the brake pedal 32. Of course, the hydraulic pressure control valve 30 (
31), when brake fluid pressure for slip control is not generated, the mask cylinder 27 and the brake 21 (22)
Since the brake pedal 27 is in a communicating state, a normal braking action is performed due to the operation of the brake pedal 27.

The opening and closing of each valve 5VI-SV4 is controlled by a brake control unit UB, which will be described later. Brake fluid pressure status to brakes 21 and 22 and each valve SV
The operational relationship with I to SV4 is summarized in the following table.

In Fig. 1, U is the control unit, which can be roughly divided into the aforementioned brake control unit UB, throttle control unit UT, and slip control control unit US. It is configured. The control unit UB controls the opening and closing of each valve 5VI-5V4 as described above based on the command signal from the control unit US. Also.

The throttle control unit UT is based on a command signal from the control unit Us.

Drive control of the throttle actuator 14 is performed.

Control unit US for slip control.

It is composed of a digital computer, more specifically a microcomputer. This control unit US has 2 sensors (or switches) 61
Signals from ~68 are input. The sensor 61 detects the opening degree of the throttle valve 13. sensor 6
2 detects whether the clutch 7 is engaged or not.

The sensor 63 detects the gear position of the transmission 8.

Sensors 64 and 65 detect the rotational speed of the left and right front wheels 2.3 as driving wheels. The sensor 66 detects the rotational speed of the left rear wheel 4 as a driven wheel, that is, the vehicle speed. The sensor 67 detects the amount of operation of the accelerator 69, that is, the opening degree of the accelerator. The sensor 68 is the handle 7
This detects the operation amount of 0, that is, the steering angle. Each of the sensors 64, 65, 66 is configured using a pickup, for example, and the sensor 61, 63, 67, 68 is configured using a potentiometer, for example.
is constituted by a switch that operates ON and OFF, for example.

In addition, the control unit) US has two basic CPUs,
It is equipped with ROM, RAM, and CLOCK, and also has an input/output interface and an A/D or D/A converter depending on the input signal and output signal.
Since these points are the same as usual when using a microcomputer, a detailed explanation thereof will be omitted. Note that the maps and the like in the following explanation are stored in the ROM of the control unit Us.

Now, next, the control contents of the control unit U will be explained in order, but it is assumed that the completeness rate S used in the following explanation is defined by the following equation (1).

WD: Number of revolutions of the driving wheels (2, 3) WL: Number of revolutions of the driven wheels (4) (vehicle speed) The throttle control unit UT provides feedback to the throttle valve 13 (throttle actuator 14) so that the target throttle opening is achieved. It is supposed to be controlled. During this throttle control, when slip control is not performed, control is performed so that the target throttle opening corresponds to the operation amount of the accelerator 69 operated by the driver at a ratio of 1:1, and the accelerator opening at this time is FIG. 12 shows an example of the correspondence relationship between and the throttle opening degree. Furthermore, during slip control, the control unit LTT performs throttle control so as to achieve the target throttle opening degree Tn calculated by the control unit US, without following the characteristics shown in FIG.

Throttle valve 1 using control unit U-cho
In the embodiment, the feedback control No. 3 is performed by PI-FD sub-control in order to compensate for fluctuations in the response speed of the engine 6. That is, when performing slip control of the drive wheels, the opening degree of the throttle valve 13 is adjusted to PI-PDff so that the current slip rate matches the target slip rate.
jJ control. More specifically, the target throttle opening degree Tn during slip control is calculated by the following equation (2).

Tn = Tn-1 -5ET -FP CWDn-WDn-1) -F D (WOn -2X WDn-1+ WOn
-2)... (2) WL: Number of revolutions of driven wheels (4) WD: Number of revolutions of driving wheels (2, 3) KP: Proportional constant Kl: 9-minute constant FP: Proportional constant FD = Differential constant SET: Target slip rate (for throttle control) above formula (2
), the throttle opening degree Tn is feedback-controlled to the rotational speed of the drive wheels so that it reaches a predetermined target slip rate SET. In other words, as is clear from the above equation (1), the throttle opening degree is controlled so that the target drive wheel rotation aWET is expressed by the following equation (3).

PI-PD using the control unit Uf described above
The control is shown in FIG. 3 as a block diagram, and "S'" shown in FIG. 3 is "operator". Further, each suffix rnJ and rn-IJ indicates the value of each signal at the current time and the previous sampling time.

During brake control slip control, control unit) UB
The rotation (slip) of the left and right drive wheels 2.3 is feedback-controlled independently to a predetermined target slip rate SOT. In other words, brake control is expressed by the following equation (
Feedback control is performed so that the drive wheel rotation speed WBT set in step 4] is reached.

In this embodiment, the target slip rate SBT of the brake is set larger than the target slip rate SET of the engine, as will be described later. In other words, the slip control of this embodiment increases or decreases the engine output to a predetermined SET (WET), and also increases or decreases the engine output to a larger 5ET (WBT).
The frequency of use of the brakes is reduced by increasing/decreasing the torque using the brakes. In this embodiment, feedback control that satisfies the above equation (4) is performed by I-FD sub-control, which has excellent stability. More specifically, the amount of brake operation (the amount of operation of the piston 44 in the valve 30.31) B
n is calculated by the following equation (5).

Bn=Bn-1 -FP (WDn-WDJ+-1) -F D (WDn -2X WDn-1+ WDn
-2)...(5) KI: Integral coefficient KD: Proportional coefficient FD: Derivative coefficient When Bn above is greater than O (when it is "positive"), it is an increase in brake fluid pressure, and when it is less than 0, it is an increase in brake fluid pressure. The pressure will be reduced. This increase/decrease in brake fluid pressure is controlled by the valve SVI~
This is done by opening and closing SV4. In addition, the adjustment of the rate of increase/decrease in brake fluid pressure is performed using the above-mentioned valves SVI to SV.
This is done by adjusting (duty control) the ratio of the opening/closing time (duty ratio) of No. 4, and the duty control is proportional to the absolute value of Bn determined by the above equation (5). Therefore, the absolute value of Bn is proportional to the rate of change in brake fluid pressure, and conversely, the duty ratio that determines the rate of increase/decrease also indicates Bn.

The I-FD sub-control by the control unit UB mentioned above is shown in FIG. 4 as a block diagram.
"S'" shown in the figure is an "operator".

Outline of Slip Control The overall outline of slip control by the control unit U will be explained with reference to FIG. 5. The meanings of the symbols and numerical values shown in FIG. 5 are as follows.

S/C Nislip control area E/G: Slip control by engine B/R Slip control by Nibrake F/B: Feedback control 0/R: Oven loop control R/Y: Recovery control B/A: Backup control A/S: Buffer control S = 0.2 Slip rate at the start of Nislip control (SS) S = 0.17: Target slip rate by brake (S ET
) S = 0, 09 Slip rate when stopping slip control by Nibrake (S EC:) S = 0, 06: Target slip rate by engine (S
ET) S = 0.01 to 0.02: Slip rate in the range where buffer control is performed S = 0.01 or less: Slip rate in the range where backup control is performed The results are shown based on the data obtained. Then, S = 0.01 and 0.02 to perform buffer control A/S, and slip rate S = 0 at the time of stopping slip control by brake.
．． 09 are left unchanged in the embodiment. on the other hand,
The target slip rate SET by the brake, the target slip rate SET by the engine, and the slip rate SS at the start of slip control are changed depending on the road surface condition, etc. In Fig. 5, as an example, ro, 17J, r
0.06J or ro.2''. and,
The slip rate S=0.2 at the start of the slip control is the slip rate at the time when the maximum grip force is generated when using spiked tires (see the solid line in FIG. 13). In this way, the reason why the slip rate at the start of slip control is set to a large value of 0.2 is so that the actual slip rate when this maximum grip force is obtained can be determined. The target slip ratios SET and SET by the engine and brake are corrected according to the slip ratio at the time of force generation.

The solid line in FIG. 13 shows how the grip force and lateral force (expressed as the coefficient of friction against the road surface) of spiked tires change in relation to the slip rate. Moreover, the broken line in FIG. 13 shows the relationship between grip force and lateral force when using normal tires.

On the premise of the above, FIG. 5 will be explained with the passage of time.

■toNt1 Since the slip rate S does not exceed S-0,2, which is the condition for starting slip control, slip control is not performed. In other words, when the slip of the drive wheels is small, the caro speed can be improved by not controlling the slip (
Driving using great grip power]. Of course, in this case, the characteristics of the throttle opening with respect to the accelerator opening are the first
It is uniformly determined as shown in Figure 2.

(2) t1 to t2 Slip control is started and the slippage rate is equal to or higher than the brake-based slip control stop point hcs=0.09). At this time, since the slip rate is relatively large, slip control is performed by reducing the torque generated by the engine and braking by the brake. Also, since the target slip rate of the brake (S = 0.17) is larger than the target slip rate of the engine (S = 0.06), the brake is However, when there is a small slip (S<0, 17), the brake is not pressurized and the slip is controlled by controlling only the engine so that the slip converges.

■t2~1+ (Recovery control) The throttle valve 13 is operated for a predetermined period of time (for example, 170 m5ec) after the slip converges (S<0, 2) I.
is maintained at a predetermined opening degree (oven loop control). At this time, S=O/2 (maximum acceleration at t2) GW
AX is required, and the maximum JL of the road surface is higher than this G WAX.
(maximum grip force of the drive wheels) is estimated. Then, the throttle valve 13 is held for a predetermined period of time as described above so as to generate the maximum grip force for the driving wheels. This control is performed to prevent the vehicle body acceleration G from dropping immediately after the slip converges because feedback control cannot respond in time because the convergence of the slip occurs rapidly. Therefore, when the convergence of slip is predicted (S=decreased from 0.2), a predetermined torque is secured in advance as described above, and acceleration performance is improved.

The optimum throttle opening Tvo for realizing the torque applied to the drive wheels that can generate the maximum grip force mentioned above is:
Although it can be determined theoretically from the torque curve of the engine 6 and the gear ratio, in the embodiment, it is determined based on a map as shown in FIG. 15, for example. This map was created using an experimental method, and G WAX is 0.15.
When the value is less than or equal to 0.4, it is set to a predetermined constant value in consideration of the measurement error of G WAX. Note that the map shown in No. 121N is for a certain gear position (for example, L speed).
, and the optimum throttle opening TVo is corrected for other gears.

■ t4 to t7 (backup control, buffer control) In order to deal with when the slip rate S decreases abnormally, backup control is performed (open loop control), that is, when s<o, o i, , the feedback control is stopped and the throttle valve 13 is opened in stages, and when the slip rate is between o, oi and 0.02, in order to smoothly transition to the next feedback control, In this backup control, collision control is performed (1+ to t5 and t6 to t7).

This is done when feedback control and recovery control cannot deal with the problem. Of course, this backup control is assumed to have a sufficiently faster response speed than feedback control.

In this embodiment, the rate of increase in the throttle opening in this pull-up control is such that 0.5% opening is added to the previous throttle opening every 14 m5 ec of sampling time of the throttle opening. .

In addition, in the above-mentioned buffer control, as shown in FIG. 16, the slow 2-torque opening T2 obtained by the feedback control calculation and the throttle opening T1 obtained by the backup control calculation are adjusted based on the current fullness rate So. The throttle opening degree To is obtained by proportional distribution.

■t7 A'tg By performing the control up to t7, there is a smooth transition to slip control using only the engine.

(Since the accelerator 69 is fully closed by the driver after Φt8, slip control is canceled. At this time, the throttle valve 13
Even if the degree of opening of the accelerator is left to the driver's will, there is no risk of slipping again because the torque has been sufficiently reduced. This is also carried out when the target throttle opening due to slip control becomes smaller than the throttle opening determined in FIG. 12, which corresponds to the accelerator opening operated by the driver.

Here, to adjust the response speed of the control system according to the degree of slipperiness of the road surface, change KI and KP (for the engine) in the above-mentioned equation (2), and KI (for the brake) in the equation (5). It is done by doing. More specifically, as shown in FIG.

The larger the road surface AL (friction coefficient), the higher the above KI or K.
P is increased (response speed is increased). The road surface color is estimated from the maximum acceleration G MAX of the vehicle body (driven wheels) obtained during slip control.

Details of slip control (flow chart) Next, Figure 6~
The details of the slip control will be explained with reference to the flowchart of FIG. 11. In the embodiment, when the automobile 1 is stuck in mud etc., brake control is used to escape from the mud etc. It also controls the stack. Note that in the following explanation, P indicates a step.

FIG. 6 (Main) After the system is initialized at Pl, it is determined at P2 whether or not the system is currently stuck (such as stuck in mud or the like and unable to move). This determination is made by checking whether a stack flag, which will be described later, has been sent. When the determination in P2 is NO, it is determined in P3 whether or not the accelerator 69 is fully closed. When the determination in P3 is No, it is determined in P4 whether or not the current throttle opening is greater than the accelerator opening. If the determination in P4 is No, it is determined in P5 whether or not slip control is currently being performed. This determination is made by checking whether the slip control flag is set. When the determination in P5 is No, it is determined in P6 whether or not a slip has occurred that requires slip control. This determination is made by checking whether a slip flag for the left and right front wheels 2.3, which will be described later, is set. This P
When the determination in step 6 is NO, the process moves to P7 and the slip control is stopped (normal driving).

If YES is determined in P6, the process moves to P8, where the slip control flag is set.

Subsequently, in P9, the initial value of the target slip rate SET for the engine (throttle) (0.06 in the embodiment) is set, and in PIO, the initial value of the target slip rate SBT for the brake (0.06 in the embodiment) is set. 17) is set. After this, brake control is performed at Pll and engine control is performed at P12 for slip control, as will be described later. In addition, P9. The initial value setting in PIO is performed based on the maximum acceleration G MAX obtained in the previous slip control from the same viewpoint as in P76 described later.

When the determination is YES in P5, the process moves to P11 described above, and the slip control is continued.

If YES is determined in P4, the slip control is no longer needed, and the process moves to P14. This Pl
4, the slip control flag is reset. Then,
Engine control is stopped at Pl5, and brake control is performed at Pl6. It should be noted that the brake control at Pl6 is performed as a countermeasure against a stuck situation.

If YES is determined at P3, the brake is released at P13, and then the processes from F14 onwards are performed.

When the determination in P2 is YES, the processes from P15 onward are performed.

7 and 8 The flowchart in FIG. 7 is interrupted by the main flowchart in FIG. 6 every 14 msec, for example.

First, in P21, each signal from each sensor 61 to 68 is input for data processing. Next, after slip detection processing, which will be described later, is performed in P22, throttle control is performed in P23.

The throttle control at P23 is performed according to the flowchart shown in FIG. First, in P24, it is determined whether the slip control flag is set, that is, whether slip control is currently being performed.

When YES in this P24, the control of the throttle valve 13 is performed for slip control, that is, without following the characteristics shown in No. 1211, to a predetermined target slip $S ET
Control is selected to achieve this. If the determination in P24 is No, the opening/closing control of the throttle valve 13 is selected to be left to the driver's will (according to the characteristics shown in FIG. 12) in P26.

After P25 and P26, control is performed in P27 to achieve the target throttle opening (control according to P68, P2O, and P71, which will be described later, or control according to the characteristics shown in FIG. 12).

FIG. 9 (Slip Detection Process) The flowchart in FIG. 9 corresponds to P22 in FIG. 7. This flowchart is for detecting whether a slip that is subject to slip control has occurred and whether or not the vehicle is stuck.

First, in P31, it is determined whether the clutch 7 is completely connected. If YES is determined in this P31, it is assumed that there is no space in the stack, and P32
The stack flag is reset in . Then, P
33, the current vehicle speed is low, for example 6.3k
It is determined whether or not it is smaller than m/h.

When the determination in P33 is No, a correction value α for slip determination is calculated in P34 according to the steering angle of the steering wheel (see FIG. 14). After this, at P35, the slip rate of the left front wheel 2 as the left driving wheel is set to a predetermined reference value of 0.
2 is larger than the value (0, 2+α) obtained by subtracting α from P34 above. With this P35 discrimination,
If YES, it is assumed that the left front wheel 2 is in a slip state and its slip flag is set. On the other hand, N at P35
When it is determined as o, the slip flag for the left front wheel 3 is reset. Note that the correction value α is set in consideration of the rotation difference between the inner and outer wheels (particularly the rotation difference between the driving wheels and the driven wheels) during turning.

After P36 or P37, P38. P39, P2O
In , the slip flag for the right front wheel 3 is set or reset in the same manner as in P35, P36, and P37.

If YES is determined in P33, the vehicle speed is low, and there will be a large error in calculating the slip rate using the vehicle speed, that is, based on equation (1). It is intended to be detected only by That is, at P41, the rotation speed of the left front wheel 2 is
It is determined whether the rotational speed is greater than the rotational speed equivalent to a vehicle speed of 10 km/h. When it is determined as YES in this P41, P
At 42, the slip flag for the left front wheel 2 is set. Conversely, when the determination is No at P41, the slip flag for the left front wheel 2 is reset at P43.

After P42 and P43, the slip flag for the right front wheel 3 is set or reset in Pd2, Pd2, and P46 in the same manner as in P41 to P43 described above.

If the determination in P31 is No, there is a possibility that the vehicle is stuck (when the driver is stuck, the driver tries to escape from the mud etc. while using the clutch in a partially engaged state).

In this case, the process moves to P51, and it is determined whether the average value of the rotational speed of the left and right front wheels 2 and 3 as driving wheels is small (for example, 2 km/h by adding 4 to the vehicle speed). ). When it is determined NO in P51, it is determined in P52 whether or not stack control is currently being performed. If P52 is determined as No, P
At b0, it is determined whether the rotation speed of the right front wheel 3 is greater than the rotation speed of the left front wheel 2. When YES is determined at Pb0, it is determined whether the rotation speed of the right front wheel 3 is greater than 1.5 times the rotation speed of the left front wheel 2.

If YES is determined in P54, a stack flag is set in P56. On the other hand, if the determination in P54 is NO, it is assumed that the stack is not in progress, and the above-mentioned P3
2 and subsequent processes are performed.

Further, when the determination in P53 is NO, in P55, the rotation speed of the left front wheel 2 is 1.5 times the rotation speed of the right front wheel 3.
It is determined whether or not it is greater than five times. Y with this P55
If the answer is ES, the process goes to P56, and if the answer is NO, the process goes to P32.

After P56, the vehicle speed is 6.3km/h at P57.
It is determined whether or not it is larger than . YES on this P57
When this happens, the target rotational speed of the front wheels 2.3 is set to be 1.25 times the driven wheel rotational speed indicating the vehicle speed (corresponding to a slip rate of 0.2). Also, if NO in P57, the target rotation speed of the front wheel 2.3 is set to 10 in P59.
is uniformly set to +n/h.

Further, if YES in P51, the brake is slowly released in P2O.

Fig. 10 (Engine control) The flowchart shown in Fig. 10 is based on P12 of Fig. 6.
Compatible.

At P61, it is determined whether the slip has transitioned to a convergence state (whether it has passed time t2 in FIG. 5). When the answer is No in P61, it is determined in P62 whether the slip rate S of the left front wheel 2 is greater than 0.2. N at P62.

In this case, it is determined in P63 whether the slip rate S of the right front wheel 3 is greater than 02. When the answer is No in P63, it is determined in P64 whether only one of the left and right front wheels 2.3 is under brake control, that is, whether the vehicle is traveling on a split road. If YES in P64, the current slip rate is calculated in P65 according to the drive wheel with the lower slip rate among the left and right front wheels 2.3 (
select low). Conversely, when P64 is NO, the current slip sA is output (select high) in accordance with the driving wheel with the larger slip ratio among the left and right front wheels 2.3. In addition,
N at P62 and P63.

In this case, the process also moves to P66.

The selection high in P65 allows the use of the brake to be further avoided by calculating the current slippage rate to suppress the slippage of the slippery drive wheel. On the other hand, the select low in P65 above is effective when driving on a split road where the friction coefficients of the road surface that the left and right drive wheels touch are different, while suppressing the slip of the drive wheel that is more likely to slip by the brake. This makes it possible to drive by taking advantage of the grip of the drive wheel on the weaker side.

In addition, in the case of this select low, in order to avoid overusing the brakes, it is advisable to take backup measures such as limiting the select low to a certain period of time, or stopping the select low when the brakes overheat.

After P65 and P66, it is determined in P67 whether the current slip ratio S is greater than 0.02. When YES in P67, the throttle valve 13 is feedback-controlled for slip control in P68. Of course, at this time, the throttle valve opening (Tn) is set to realize the target slip rate SET set in P65 and P66 or changed in P76, which will be described later, and the torque applied to the drive wheels is Adjustments are also made to the speed at which .

If No in P67, it is determined in P69 whether or not the current fill rate S is greater than 0.01. If YES in P69, the buffer control described above is performed in P2O. Also, if fP69 is No, P71
In this step, the backup control described above is performed.

On the other hand, if YES in P61, the process moves to P72, where it is determined whether a predetermined time (time for performing recovery control, 170 msec as described above in the embodiment) has elapsed after the slip convergence. If NO in P72, the processes from P73 onward are performed to perform recovery control. That is, first, in P73, the maximum acceleration G MAX of the vehicle 1
is measured (time t2 in Fig. 5). Then at P74.

Optimal throttle opening T to obtain this G MAX
v□ is set (see Figure 15). Further, in P75, the optimum throttle opening Tv□ in P74 is corrected according to the current gear position of the transmission 8. That is, since the torque applied to the driving wheels differs depending on the difference in gear position, the optimal throttle opening TVQ for a certain standard gear position is set in P74, and this difference in gear position is corrected in PI5. be. After this, at P76.

Estimating the friction coefficient of the road surface from G WAX in P73,
Change both the target slip rate SET and SBT for slip control using the engine (throttle) and brake. Note that how to change the target slip rates SET and SBT will be described later.

If YES in P72, this means that the recovery control has ended, and the processes from P62 onwards are performed.

Fig. 11 (Brake control) The flowchart shown in Fig. 11 is based on the Fil in Fig. 6.
and PI3 compatible.

First, in P81, it is determined whether or not the stack is currently in progress. If NO at P81, at P82,
The limit value (maximum value) of the brake response speed Bn (corresponding to the duty ratio for opening/closing control of SVI to SV4) is set as a function according to the vehicle speed (the higher the vehicle speed, the larger the value). Conversely, when P81-cYES, the limit value BLM is set at P83 as a constant value smaller than that at P82. Note that the processing in P82.83 takes into consideration that if the Bn calculated by the formula [5] above is used, the rate of increase/decrease in brake fluid pressure will be too fast, which may cause vibrations, etc. It will be done.

In addition, in P83, it is particularly undesirable for the braking force applied to the drive wheels to change suddenly in order to escape from the stuck state, so a small constant value is set as the limit value.

After P82 or P83, it is determined in P84 whether the slip rate S is larger than 0, 09, which is the brake control stop point. When YES in P84, the operation speed Bn of the right front wheel brake 22 is calculated in P85 (Bn in the I-FD control in Fig. 4).
Of course, the setting of Bn in P85 is also performed together with the adjustment of the speed in the direction of increasing the torque applied to the drive wheels. After this, in P86, it is determined whether the above Bn is larger than rQJ. This determination is performed to determine whether or not the brake pressure is in the increasing pressure direction, assuming that the pressure increasing direction of the brake is positive and the pressure decreasing direction is negative.

When P86-1'YES (7), in P87, B
It is determined whether n>BLM. YES on P87
In this case, after setting Bn to the limit value BLM, P8
At 9, the pressure of the right brake 22 is increased. Also,
If NO in P87, the pressure is increased in P89 using the Bn value set in P85.

If NO in P88, Bn is “negative” or rQ
J, so after converting Bn to an absolute value using P2O, P91
- 93 processes are performed. These P91 to P93 are when depressurizing the right brake 22, and P87, P88, and P8
9 processes are supported.

After P89 and P93, the process moves to P94, and pressure increase or decrease processing is performed for the left brake 21 in the same way as for the right brake 22 (process corresponding to P84 to P93).

On the other hand, if NO in P84, it is time to cancel the brake control, so the brake is released in P95.

In addition, between P85 and P86, the actual rotation speed and target rotation speed (actual slip rate and target slip rate) of the driving wheels
When the difference is large, it is preferable to make a correction such as reducing the integral constant Kl in equation (5) above, in order to prevent deterioration of acceleration and engine stalling due to excessive braking.

Target accuracy SET, change SBT (P76) above P
The target slip ratios SET and SB of the engine and brake that are changed in step 76 are changed as shown in FIG. 17, for example, based on the maximum acceleration G MAX measured in step P73. As is clear from FIG. 17, in principle, the larger the maximum acceleration GMAX, the larger the target slip rates SET and SET should be. Limit values are set for each of the target slip rates SET and SET.

Next, we will explain how the setting relationship between the target slip ratio SET and SBT affects the driving sensation of the automobile I.

■The grip force SET and SBT of the drive wheels are offset in the vertical direction in FIG. 17 as a whole. Then, to increase the grip force, perform an upward offset. In other words, as shown in Fig. 13, the characteristics of spiked tires include a slip rate of 0.2.
Since the coefficient of friction is increasing up to about 0.3, the above can be said as long as the slip ratio is used within the range of 0.2 to 0.3.

■Acceleration feeling The acceleration feeling changes by changing the "difference" between SET and SBT, and the smaller this "difference" is, the greater the acceleration feeling becomes. That is, when SET is set to a value smaller than SBT as in the embodiment, brake control mainly acts when the slip rate is large, and engine control acts mainly when the slip rate is small. therefore,
When the "difference" between SET and SBT is made smaller, brake control and engine control come closer to working with almost the same distribution. In other words, the brakes are used to reduce the torque generated by the engine to drive the drive wheels, and if the torque is rapidly increased for acceleration, simply loosening the brakes will increase the torque to the drive wheels without delay in response. do.

■ Smoothness of acceleration Increase SBT, that is, make it relatively larger than SET. This means that by increasing the priority of engine control, smooth torque changes, which are an advantage of engine control, can be more effectively generated.

(2) Stability during cornering Make SET small, that is, relatively smaller than SBT. As is clear from Fig. 13, this means that the slip rate at which the maximum grip force occurs is S = 0.2~
In the range of 063 or less, by lowering the target slippage rate, the grip force of the driving wheels is reduced, while the lateral force is increased and the bending force is increased.

The above-mentioned characteristics (modes) from (1) to (2) can be selected manually depending on the driver's preference.

As mentioned above, the speed in the direction of increasing the torque applied to the drive wheels is smaller when the road surface piece is small than when it is large (Figure 19), but due to this difference in road surface, the speed in the direction of increasing the torque applied to the drive wheels is smaller. FIG. 18 shows how the rotational speed changes. In this way, the speed at which the torque applied to the driving wheels increases is adjusted according to the road surface k, so that while the slip is quickly converged to a predetermined target value, the driving wheels do not slip again due to the applied torque becoming excessive. can be reliably prevented.

Next, another embodiment of the present invention will be described. In this embodiment, the rate of increase in torque applied to the driving wheels is adjusted not only automatically using rGMAXJ described above but also manually. In other words, the degree of slipperiness of the road surface is manually input. Therefore, in this embodiment, the manual switch 71 (
(See Figures 1 and 20). This switch 71 includes, for example, a push-button button 71a for switching between "automatic setting" and "manual setting" in the above embodiment, as well as two sliding levers 71b and 71c.
has. The lever 71b is used to input the type of tire (distinguishing between snow tires, normal tires, etc.).

In addition, the lever 71c is difficult to slip on the road surface (dry),
This is entered as slippery (wet). The levers 71b and 71c are capable of input adjustment (sliding) in a stepwise or stepless manner. The road surface p(
(corresponding to FIG. 19) is set to 1, for example, as follows.

That is, in order from the side where the road surface is increased to the side where it is decreased, for example, "snow and dry", "normal and dry", "snow and x"/t.
, and is said to be "normal and wet".

Setting of the road surface condition (final) accompanying switching between "auto" and "manual" using the button 71a described above is performed, for example, as shown in the flowchart shown in FIG. 21.

That is, taking the case of brake control as an example, in P85 of FIG. 11, Bn is set corresponding to "auto".

After P85, it is determined whether or not the current mode is auto mode using the PIOI shown in FIG. And this PIOI
If the determination is YES, it is left as is (Fig. 11P
If Plol is No, Bn is changed as set by the levers 71b and 71c at P2O3, and then the process moves to P86 in FIG.

Incidentally, engine control is also controlled in the same manner.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

■In addition to engine control and brake control, the torque applied to the drive wheels can be adjusted by adjusting the engagement state of the clutch 7 or by changing the gear ratio of the transmission 8 (especially effective in the case of a continuously variable transmission) This can be done by any one or a combination of appropriate components that can adjust the torque applied to the drive wheels.

■As for the adjustment of the generated torque of the engine 6, it is preferable to change and control the factors that most affect the generated output of the engine. In other words, it is preferable to adjust the generated torque by so-called load control. ), it is preferable to adjust the air-fuel mixture amount, and for diesel engines, it is preferable to adjust the fuel injection amount. However, the load control is not limited to this, and may be performed by adjusting the ignition timing in an Otto type engine, or by adjusting the fuel injection timing in a diesel engine. Furthermore, in the case of engines that require supercharging, this may be done by adjusting the supercharging pressure.Of course, the power source is not limited to an internal combustion engine, but may also be an electric motor; The torque may be adjusted by adjusting the power supplied to the motor.

(2) In the automobile 1, the front wheels 2.3 are not limited to driving wheels, but the rear wheels 4.5 may be driving wheels, or all four wheels may be driving wheels.

■In order to detect the slip state of the drive wheels, it is possible to directly detect the rotation speed of the drive wheels as in the embodiment, but it is also possible to predict the slip state according to the state of the vehicle. In other words, it may be detected indirectly. Such vehicle conditions include, for example, an increase in the generated torque or rotational speed of the power source, a change in the degree of accelerator opening, a change in the rotation of the drive shaft, the steering condition (cornering), and the floating condition of the vehicle body (acceleration). , loading capacity, etc. In addition to this, the prediction of the slip state of the drive wheels can be made even more appropriate by automatically detecting or manually inputting atmospheric temperature high/low, rain, snow, icy road conditions, etc. You can also do it.

(Φ Brake fluid pressure circuit and sensor 64, 64 in Fig. 2)
．． 66 can utilize the existing ABS (anti-brake lock system).

(The speed may be adjusted in the direction of decreasing the torque applied to the φ drive wheel. In this case, as well as adjusting the speed in the direction of increasing the applied torque, when the road surface is slippery, It is better to make the response speed slower than when it is difficult to slip.

■The speed of change of applied torque (response speed) is not only achieved by adjusting the control gain of equations (2) and (3) as in the example, but also by the control system that affects the speed of change of applied torque. This can be done by adjusting appropriate parameters.

(Effects of the Invention) As is clear from the above description, the present invention quickly converges the magnitude of the slip of the drive wheels toward the target value, while preventing large slips from occurring again during slip control. The situation can definitely be avoided.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing an example of a brake fluid pressure control circuit. FIG. 3 is a block diagram when performing feedback control of the throttle valve. FIG. 4 is a block diagram when feedback controlling the brakes. Figure S5 is a graph schematically showing a control example of the present invention. 6 to 11 and 23 are flowcharts showing control examples of the present invention. FIG. 12 is a graph showing the characteristics of throttle opening relative to accelerator opening when slip control is not performed. FIG. 13 is a graph showing the relationship between the grip force and lateral force of the driving wheels in terms of the relationship between the slip rate and the friction coefficient with respect to the road surface. FIG. 14 is a graph showing correction values when correcting the slip rate at the start of slip control according to the steering angle of the steering wheel. FIG. 15 is a graph showing the optimum throttle opening corresponding to the maximum force U speed during recovery control. FIG. 16 is a graph showing the relationship between slip rate and throttle opening when performing buffer control. FIG. 17 is a graph showing an example of a map used when determining the target slip rate. FIG. 18 is a graph schematically showing the difference in response speed of the control system between a high road surface and a low p road surface. The $19 figure is a graph showing the relationship between road surface μ and response speed. FIG. 20 is a diagram showing an example of a mode switch for manually inputting the slipperiness of a road surface. FIG. 21 is a flowchart showing main parts in another control example of the present invention. FIG. 22 is an overall configuration diagram of the present invention. 1: Car 2.3: Front wheel (driving wheel) 4.5: Rear wheel (driven wheel) 6: Engine (power source) 7: Clutch 8: Transmission 13: Throttle valve 14: Throttle actuator 21-24 Brake 27: Mask cylinder 30.31: Hydraulic pressure control valve 32 Brake pedal 61: Sensor (throttle opening) 62: Sensor (clutch) 63: Sensor (gear) 64.65: Sensor (drive wheel rotation speed) 66: Sensor ( Driven wheel rotation speed) 67 sensor (accelerator opening) 68: sensor (steering wheel steering angle) 69 near accelerator 0: handle 71: road condition input switch SVI to SV4: electromagnetic opening/closing valve U: control unit Fig. 12 hand IF Fig. 13 S (ζ facing JPI Fig. 15 ea Fig. 16 1 - Be 1 no mail 4 (s) Fig. 17 GMAX Fig. 18 ot, L2t3 Weighing box Fig. 19 (GMAX) Figure 22 Figure 20 Procedural amendment (method) October 2, 1986

Claims (1)

[Claims] (1) In an automobile slip control device that prevents excessive slip of the driving wheels against the road surface by controlling the torque applied to the driving wheels, a torque adjustment means for adjusting the torque applied to the driving wheels. a slip detection means for detecting a slip state of the drive wheels relative to the road surface; and a slip control means for receiving an output from the slip detection means and controlling the torque adjustment means so that the slip of the drive wheels reaches a predetermined target value. and a road surface condition detecting means for detecting the state of slipperiness of the road surface, and a road surface condition detecting means for detecting the state of slipperiness of the road surface, and a road surface condition detecting means for detecting a state of slipperiness of the road surface, and a means for detecting the slipperiness of the road surface. 1. A slip control device for an automobile, comprising means for changing a response speed to be set.