JPS6331858A - Slip controller for automobile - Google Patents

Abstract

PURPOSE:To make such slip control as capable of quickly responding to acceleration requirement attainable, by installing a compensating device which compensates the slip control by a slip controlling device in the direction that enhances a ratio of the slip control by a brake at the acceleration requirement. CONSTITUTION:In this controller, there are provided with a generated torque regulating device B controlling a throttle valve or the like of a power source A for an engine or the like and regulating the generated torque, and a braking force regulating device D regulating the braking force produced by a driving wheel brake C. And also there is provided with a slip detecting device E detecting a slip state to a road surface of driving wheels, and when a slip of the driving wheel is more than the specified value, these regulating devices B and D are operated by a slip controlling device F, making them restrain the slip from occurring. In addition, there is provided with an acceleration detecting device G detecting the acceleration requirement of a driver, and at the time of detecting this acceleration requirement, this slip control is made so as to be compensated in a direction where a ratio of the slip control using the brake is enhanced.

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. This relates to a control device.

(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.

Conventionally, methods for performing this type of slip control are disclosed in Japanese Patent Application Laid-Open No. 58-16948 or Japanese Patent Application Laid-Open No. 60-56.
There is one shown in Publication No. 662.

Both of the technologies disclosed in these publications utilize the application of braking force to the drive wheels by the brake and the reduction of the generated torque of the engine itself as a power source to reduce the torque applied to the drive wheels. This is how it is done. More specifically, in the method disclosed in Japanese Patent Application Laid-open No. 58-16948, when the slip of the drive wheel is small, only the braking of the drive wheel is performed, but when the slip of the drive wheel becomes large, this drive wheel is braked. In addition to braking, it also reduces the torque generated by the engine. Also, JP-A-6
In the system disclosed in Publication No. 0-56662, when the slip of only one side of the left and right drive wheels is large, braking is applied only to the drive wheel of the one side with the large slip.
When the slips of both the left and right drive wheels are large, braking is applied to both drive wheels and the torque generated by the engine is reduced. In this manner, the systems disclosed in both of the above-mentioned publications mainly utilize braking of the drive wheels by the brake, and supplementarily reduce the torque generated by the engine.

(Problems to be Solved by the Invention) The slip control by adjusting the braking force and the slip control by adjusting the generated torque described above each have advantages and disadvantages.

In other words, when using braking force, although it is excellent in terms of responsiveness, it is easy to cause shock and has problems in terms of driving feeling, and it is difficult to use energy effectively or ensure brake reliability. becomes disadvantageous. On the other hand, slip control by adjusting the generated torque is advantageous in terms of driving feeling as it provides smooth torque fluctuations and energy efficiency as it does not generate unnecessary torque.
There is a problem with responsiveness.

From the above-mentioned point of view, at least when the slip of the drive wheels is large, performing slip control using both the application of braking force by the brakes and the reduction of the generated torque from the engine is effective in quickly converging this slip. In addition to this, it is also possible to appropriately balance responsiveness, driving fall, energy efficiency, and securing reliability of the brake.

In this way, when sleep control is performed by both applying braking force and reducing the generated torque, the control ratio, that is, how much of the reduction in torque applied to the drive wheels due to slip control is shared? However, this poses a problem. In particular, when a driver requests acceleration, it is desirable to be able to promptly respond to the acceleration request. In other words, while preventing excessive slip of the drive wheels due to slip control,
What is desired is something that can quickly respond to requests for acceleration.

In particular, if the above control ratio is set from the perspective of avoiding the use of the brakes as much as possible, the torque generated by the engine as a power source will be significantly reduced, and this reduction in generated torque will result in deterioration of acceleration performance. The problem is how to prevent this (response R of increasing the generated torque to cope with the acceleration request).

The present invention was made in consideration of the above circumstances, and
Assuming that the slip control of the driving wheels is performed by appropriately applying both braking force to the driving wheels and reducing the torque generated by the power source itself such as the engine, the system is designed to respond quickly to requests for acceleration. The purpose of the present invention is to provide a slip control device for an automobile.

(Means and effects for solving the problem) In order to achieve the above-mentioned object, in the present invention, when there is a request for acceleration, correction is made to increase the ratio of slip control by the brake. be. In other words, increasing the ratio of slip control by the brake means that the degree to which the brake suppresses the torque generated by the power source becomes stronger.In other words, the power source generates torque with a considerable margin during slip control. This means that when the slip settles and the brake is released, rapid acceleration can be obtained using the above-mentioned surplus torque. When acceleration is not requested, the brake control ratio is reduced to ensure driving feel, energy efficiency, and brake reliability. Although it is possible to detect whether or not an acceleration request is being made by looking at the rate of change of the accelerator, as is normally done, it is also possible to detect whether a request for acceleration is being made by checking the rate of change of the accelerator, etc. It may also be a request for acceleration.

Specifically, as shown in Fig. 19, 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, the torque generation a generated torque adjusting means for adjusting the generated torque of the power source, a braking force adjusting means for adjusting the braking force of the driving wheel brake; a slip detecting means for detecting a slip state of the driving wheel with respect to the road surface; Upon receiving the output from the detection means, when the slip of the driving wheels is equal to or greater than a predetermined value, the generated torque adjusting means and the braking force adjusting means are operated to reduce the generated torque of the power source and apply braking force to the driving wheels. a slip control means that performs slip control by the brake; an acceleration detection means that detects a request for acceleration from the driver; and a correction means for correcting in the direction of increasing the value.

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

Overview of overall configuration In Fig. 1, a car 1 has left and right front wheels 2 that serve as driving wheels.
．． 3 and left and right rear wheels 4.5 serving as driven 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 is transmitted to a clutch 7, a transmission 8. After passing through the differential gear 9, the signal is transmitted to the left and right front wheels 2.3 as driving wheels via the left and right drive shafts 10.11. In this way, the automobile 1 is of the FF type (front engine/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/help 13. And the throttle/
The opening and closing of the help 13 is controlled electromagnetically by a throttle actuator 14. In addition,
The throttle actuator 14 may be constructed of an appropriate motor such as a DC motor, a step motor, or one driven by fluid pressure such as oil pressure and controlled electromagnetically.

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. This disc brake includes a disc 25 that rotates together with one wheel and a caliper 26, as is known. This caliper 2
6 holds the brake hat and is equipped with a wheel cylinder, and the brake pad is applied to the disc 25 with a force corresponding 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.

As shown in the diagram of brake fluid pressure control circuit 7JSz, the fluid pressure control valve 30.3
1 each have a cylinder 41 and a piston 42 that is slidably inserted into the cylinder 41. This piston 42 allows the inside of the cylinder 41 to be expanded into a variable volume chamber 43.
and a control room 44. This volume variable chamber 43
is a path through which brake fluid pressure passes from the mask cylinder z7 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 (2
It is possible to generate brake fluid pressure for 2), and it is also possible to increase/decrease or maintain the generated brake fluid pressure.

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 valve 46 is connected to the piston 4
2 is displaced in the direction of decreasing the volume of the variable volume chamber 43, the inlet side to the variable volume chamber 43 is closed.

As a result, the brake fluid 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. There is.

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 using this hydraulic pressure control valve 30 (31) (slip control), 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 pressure reduction), the brake is applied by operating the brake pedal 32. Of course, the hydraulic control valve 30
(31), when brake fluid pressure for slip control is not generated, the mask cylinder 27 and brake 21 (22)
) are in communication, so normal braking action is performed due to the operation of the brake pedal 27.

Each of the valves SVI to SV4 is controlled to open and close 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 first table.

Control unit mff1
In addition to the brake control unit UB mentioned above, it is comprised of a throttle control unit UT and a slip control control unit US.

Control unit UB is control unit U
Based on the command signal from S, each valve S
Performs opening/closing control of v1 to SV4. It also controls the drive of the throttle actuator 14 based on command signals from the throttle/torque control unit UT4t and control unit US.

The slip control control unit (US) is constituted by a digital computer, more specifically a microcomputer. Signals from each sensor (or switch) 61 to 68 are input to this control unit US. The sensor 61 detects the opening degree of the throttle valve 13. The sensor 62 detects whether the clutch 7 is engaged.

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 to the above, when the driver manually inputs a request for acceleration, a signal from the switch (driving mode selection switch) 71 for this purpose is input to the control unit Us.

The control unit US basically consists of a CPU,
It has ROM, RAM, CLOCK, T-5, and other input/output interfaces, and also has an A/D or D/A converter depending on the input signal and output signal, but these points are not handled by the micro There is no difference from normal use when using a computer, so
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.

Next, the control contents of the control unit U will be explained in order, and the slip rate S used in the following explanation shall be 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) Throttle control control unit UTt-k operates the throttle valve 13 (throttle actuator 14) to achieve the target throttle opening. It is controlled by feedback. 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 (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. Also,
The control unit UT, during slip control,
Without following the characteristics shown in FIG. 12, the throttle control is performed so as to achieve the target throttle opening n calculated by the control unit (US).

In the embodiment, the feedback control of the throttle valve 13 using the control unit 1-UT is performed by the engine 6.
In order to compensate for fluctuations in response speed, PI-FD sub-control is used. That is, during slip control of the driving wheels, the opening degree of the throttle valve 13 is sub-controlled by PI-FD so that the current slip rate matches the target slip rate. More specifically, the target throttle opening degree Tn during slip control is calculated by the following equation (2).

Tn= Tn-1 -3ET -5ET -F P (WDn -WDn-1) -F D (
WDn-2X WDn-1+ WDn-2)...
(2) WL: Number of revolutions of driven wheels (4) WD: Number of revolutions of driving wheels (2, 3) KP: Proportional constant KI: Integral constant FP: Proportional constant FD: Differential constant SET: Target fill rate (throttle control ) The 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 driving wheel rotation speed WET is expressed by the following equation (3).

PI-FD using the above-mentioned control unit) UT
The sub-control is shown in FIG. 3 as a block diagram, and "S'" shown in FIG. 3 is an "operator". Further, each suffix rnJ, rn-1'' indicates the value of each signal at the current time and the previous sampling time.

During brake control slip control, control
The rotation (slip) of the left and right drive wheels 2.3 using B is
Feedback control is performed so that the left and right sides independently achieve a predetermined target slip rate SET. In other words, brake control is performed through feedback control so that the driving wheel rotation speed WBT is set by the following equation (4).

In this embodiment, the target fullness rate SET of the brake is set to be larger than the target fullness 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. I7
In this embodiment, feedbank control that satisfies equation (4) is performed by I-FD control, which has excellent stability. More specifically, the brake operation amount (operation H of the piston 44 in the valve 30.31
)B n is calculated by the following equation (5).

Bn=Bn-1 -F P (WDn -WDn-1) -F D (
WDn-2X WDn-1+ WDn-2) Jar...(
5) K■: Integral coefficient KD: Proportional coefficient FD: Derivative coefficient When the above Bn is larger than O (when it is "positive"), the brake fluid pressure is increased, and when it is less than O, it is 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 control by the control unit UB described above is shown in FIG. 4 as a block diagram.
"S'" shown in the figure is an "operator".

Overall outline of slip control The overall outline of slip control by control unit U will be explained with reference to FIG. 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 due to brake (S E
T) S=0.09Slip rate when stopping slip control by brake (S BC) s=o, 06: Target slip rate by engine (S BC)
ET) S = O, O1 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 information is based on data obtained from driving.

Then, S=o, oi and 0.02 to perform buffer control A/S
) Furthermore, the slip rate S=0.09 at the time of stopping the slip control by the brake is left unchanged in each embodiment.

On the other hand, the target slippage rate S by the brakes, the target slippage rate SET by the engine, and the slippage rate SS at the start of slip control change depending on road surface conditions, etc., and FIG. 5 shows an example of this. asro, 17J
, rO,06J or rO,2J. 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.
Depending on the slip rate when the maximum grip force is generated, set the target slip rate by the engine and brake, SET, SB.
T is corrected. The solid line in FIG. 13 shows how the magnitude of the grip force and lateral force when using a spiked tire (shown as a coefficient of friction against the road surface) changes in relation to the slip rate. Furthermore, the broken line in FIG. 13 shows the relationship between grip force and lateral force when using a normal tire. Based on the above premise, FIG. 5 will be explained as time passes.

■to-tl Since the slip rate S does not exceed S20.2, which is the condition for starting slip control, slip control is not performed. That is, when the slip of the driving wheels is small, acceleration performance can be improved by not controlling the slip (driving using a large grip force). Of course, at this time,
The characteristics of the throttle opening with respect to the accelerator opening are the 12th
It is uniformly determined as shown in the figure.

(B) t1-t2 This is when slip control is started and the slip rate is equal to or higher than the brake-based slip control stop point cs=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 = o, os), 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.

■ t2-14 (Recovery control) The throttle valve 13 is maintained at a predetermined opening degree for a predetermined time (for example, 170 m5ec) after the sleeve 2 converges (S<0.2) (oven loop control). At this time, the maximum acceleration G WAX at the time S=0/2 (t2) is determined, and the maximum acceleration of the road surface (maximum grip force of the driving wheels) is estimated from this G and AX. 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 and gear ratio of the engine 6, 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 MAX is 0.15.
When it is less than 0.4 and more than 0.4, it is set to a predetermined constant value in consideration of the measurement error of G MAX. It should be noted that the map shown in FIG. 12 is based on the assumption that the vehicle is at a certain gear position (for example, 1st gear), and the optimum throttle opening Tvo is corrected at other gear positions.

■ t4 to t7 (Backup control, buffering system 'a) Backup control is performed in order to deal with when the slip rate S decreases abnormally (oven loop system #), that is, when S<0, 01. At this time, the feedback control is stopped and the throttle valve 13 is opened in stages. When the slippage rate is between 0.01 and 0.02, buffer control is performed in order to smoothly transition to the next feedback control (t4 to t5 and t6 to t7). This /Henk amplifier control is performed when feedback control or recovery control cannot cope with the problem. Of course, this backup control is assumed to have a sufficiently faster response speed than feedback control.

In the embodiment, the increase rate of the throttle opening in this backup control is set to 0 for the previous throttle opening at every sampling time L4 msec of the throttle opening.
．． This is an addition of 5% opening.

In addition, in the above buffer control, as shown in FIG. 16, the throttle opening degree T2 obtained by the feedback control calculation and the throttle opening degree T1 obtained by the backup control calculation are proportionally distributed according to the current fullness rate So. The throttle opening degree TO is obtained by doing this.

■t7 to 78 By performing the control up to t7, there is a smooth transition to slip control using only the engine.

2) Since the accelerator 69 was fully closed by the driver after t8, the slip control was stopped. At this time, the throttle valve 13
Even if the opening degree is left to the driver's will, there is no risk of slipping again because the torque has been sufficiently reduced. In addition to fully closing the accelerator, in the embodiment, the slip control is canceled when the target throttle opening due to the slip control is lower than the throttle opening determined by FIG. 12, which corresponds to the accelerator opening operated by the driver. I also try to do this when it gets smaller.

Here, in order to increase the brake control ratio when there is a request for acceleration, in the embodiment, as shown in FIG.
The target slip rate SBT for brake control is corrected in the direction of decreasing it. That is, from t1 in FIG.
t2. The period between t3 and t4 is a time when acceleration is requested when the accelerator depression speed is higher than a predetermined value, and at this time, the target slip rate SET of the brake control is corrected to be lowered. By reducing SET in this way, the "difference" between SET and SET becomes smaller, and as a result,
Even if the current slip rate is the same, the braking force of the brake at that time will be large, and the excess torque generated by the engine 6 will increase as the braking force increases. Therefore, when the slip becomes small and the brake is released, the above-mentioned surplus torque of the engine 6 quickly accelerates the vehicle. Of course, in order to increase the ratio of this brake control, as mentioned above, SET and SET
Since it is sufficient to reduce the "difference" between the two, either or both of reducing SBT and increasing SET may be performed.

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

Figure 6 (Main) After the system is initialized at the PI, it is determined at P2 whether or not it is currently stuck (a state where it is stuck in mud etc. and cannot move). The determination is made by checking whether a stack flag, which will be described later, is set.If the determination in P2 is NO, it is determined in P3 whether or not the accelerator 69 is fully closed.In this P3, If the determination is NO, it is determined in P4 whether the current throttle opening is greater than the accelerator opening.If the determination is NO in P4, the determination is made in P5 that slip control is currently in progress. This determination is made by checking whether or not the slip control flag is set.If the determination is NO at P5, the program proceeds to P6 to perform slip control. It is determined whether or not a slip has occurred.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 P6
If the determination is No in step P7, 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 example)
is set, and an initial value (0.17 in the embodiment) of the target slip rate SET for the brake is set in Plo. After this, brake control is performed at Pil and engine control is performed at PI2 for slip control, as will be described later. Note that the initial value setting at P9 and pH is made from the same viewpoint as P76, which will be described later, based on the maximum acceleration G14AX obtained in the previous slip control.

When the determination is YES in P5, the process moves to the above-mentioned FIL and the slip control is continued.

If YES is determined in P4, the slip control is no longer needed, and the process moves to PI4. This PI
4, the slip control flag is reset. Then,
Engine control is stopped at PI5, and brake control is performed at PI6. It should be noted that this brake control by PI6 is performed as a countermeasure against a stuck situation.

If YES is determined at P3, the brake is released at PI3, and then the processes from P14 onwards are performed.

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

7 and 8 The flowchart of FIG. 7 is interrupted, for example, at 14 ms ec@ with respect to the main flowchart of FIG.

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 P24, the control of the throttle valve 13 is selected for slip control, that is, a control that does not follow the characteristics shown in FIG. 12 and achieves a predetermined target fullness rate SET. Also, in P24, No.
When it is determined that the opening/closing control of the throttle valve 13 is left to the will of the driver (according to the characteristics shown in FIG. 12), the opening/closing control of the throttle valve 13 is selected in P26. This P2
5. After P26, control is performed in P27 to achieve the target throttle opening (P68 described later).
, P2O, P71 or control according to the characteristics shown in FIG. 12).

Figure 9 (Slip Detection Process) The flowchart in Figure 9 corresponds to P22 in Figure 7.This flowchart determines whether or not a slip that is subject to slip control has occurred, and whether or not a slip has occurred that is subject to slip control. This is to detect whether or not the

First, at P 3 ], it is determined whether the clutch 7 is completely connected. If YES is determined in P31, it is assumed that the stack is not in progress, and P31 is determined to be YES.
At 32, the stack flag is reset. Next, in P33, the current vehicle speed is low, for example 6.
It is determined whether the speed is smaller than 3 km/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, in P35, the slippage rate of the left front wheel 2 as the left driving wheel is set to a predetermined reference value of 0.
It is determined whether or not the value is larger than the value (0, 2+α) obtained by adding α in P34 to P34. With this P35 determination, Y
In the case of ES, it is assumed that the left front wheel 2 is in a slip state, and the slip flag is set. On the other hand, NO on P35
When it is determined that this is the case, the slip flag for the left front wheel 3 is reset. Note that the correction value α is set in consideration of the rotational difference between the inner and outer wheels (especially the rotational difference between the driving wheel and the driven wheel) 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.

P42) After P43, the slip flag for the right front wheel 3 is set or reset in P44, P45, 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, whether it is 2 km/h or less in terms of vehicle speed). ), if it is determined No in P51, P
At 52, it is determined whether stack control is currently in progress. When the determination is No in P52, it is determined in P53 whether the rotation speed of the right front wheel 3 is greater than the rotation speed of the left front wheel 2. If YES is determined in P53, the rotation speed of the right front wheel 3 is 1.5 of the rotation speed of the left front wheel 2.
It is determined whether or not it is greater than double.

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 number of revolutions of the left front wheel 2 is 1.5 times the number of revolutions 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
, 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 ratio of 0.2). At the time of P59, the front wheel? , 3 target rotation speed is lO
It is uniformly set to km/h. When YES at P51, the brake is slowly released at P2O.

FIG. 10 (Engine control) The flowchart shown in FIG.
, 2 corresponds to 7.

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. If NO in P62, it is determined in P63 whether the slip rate S of the right front wheel 3 is greater than 0°2. If the answer is No in P63, then in P64 the left and right front wheels 2.
It is determined whether only one side of 3 is under brake control, that is, whether the vehicle is traveling on a split road pipe. P
If YES in P64, move the left and right front wheels 2.
The current slippage rate is calculated according to the drive wheel with the lower slippage rate among 3 (select low). Conversely, if NO in P64, the slippage rate of the left and right front wheels 2 and 3 is calculated. The current speed is set according to the drive wheel to the larger circle (select high).Also, P62) Even if P63 is NO, P6
Move to 6.

Select high at upper wpss allows the use of the brake to be further avoided by calculating the current slip rate in order to suppress the slip of the slippery drive wheel. On the other hand, when driving on a split road where the friction coefficients of the road surface on which the left and right drive wheels touch the ground are different, the select low in P65 described above suppresses the slippage of the drive wheel that is more likely to slip by the brake, and This makes it possible to drive by taking advantage of the grip of the drive wheel on the side where it is difficult to rotate.

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 fill rate S is greater than 0.02. When YES in P67, in P68 the throttle valve 13 is set to feedback M for slip control.
I will control you. Of course, at this time, the throttle valve opening (Tn.) is set at the target slip rate S set at P65 and P66 or changed at P76, which will be described later.
It is set to realize ET.

When P67 is No, it is determined in P2O whether the current fill rate S is greater than 0.01. If YES at P2O, the buffer control described above is performed at P2O. Also, if P2O 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 slip convergence diameter time (time for performing recovery control, 170 msec as described above in the embodiment) has elapsed. If No in P72, the processes from P73 onwards are performed to perform recovery control. That is,
First, in P73, the maximum acceleration G WAX of the automobile 1 is calculated (time t2 in Fig. 5). Next, in P74, the optimum throttle opening Tvo to obtain this G MAX is set (15th (see figure).Furthermore,
At P75, P
The optimum throttle opening degree Tv□ at 74 is corrected. That is, since the torque applied to the driving wheels differs depending on the difference in gear position, the optimum throttle opening degree Tvo for a certain reference gear position is set in P74, and this difference in gear position is corrected in P75. be. After this, P76
In this step, the coefficient of friction of the road surface is estimated from G MAX in P73, and both the target slip rates SET and SBT for slip control by the engine (throttle) and brake are changed. Note that this target slip rate SET. How to change the 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 corresponds to the pH and PI3 in FIG. 6.

First, in P79, it is determined whether acceleration is currently requested. In the embodiment, this determination is made by checking whether the depression speed of the accelerator 69 is equal to or higher than a predetermined speed, as described above. This P79 judgment is YES
In the case of S, the target slip rate SET of brake control is corrected in the direction of decreasing in P2O, and then the process moves to P81.

Conversely, if the answer is No in P79, the process directly proceeds to P81 without going through P2O. Note that when the acceleration request is selected by switch 71 (see Figure 1), P7
The determination of the acceleration request at step 9 is made by checking the operating state of this switch 71.

In P81, it is determined whether or not it is currently stacked. If No in P81, in 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 it becomes). Set as . Conversely, if YES in P81, the limit value BLM is set to be smaller than that in P82 in P83.
Set as a permanent plant. In addition, the processing in P82.83 takes into account that if the same Bn calculated by equation (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).
ni Aimura). After this, in P86, the above Bn is rQJ
It is determined whether or not the value is larger than that. This determination determines whether or not the brake pressure is increasing, assuming that the brake pressure increasing direction is positive and the pressure decreasing direction is negative.

If YES on P86, on P87, Bn) BL
It is determined whether it is M or not. When YES in P87, after setting Bn to the limit value BLM, the pressure of the right brake 22 is increased in P89. Also, if NO in P87, with the Bn value set in P85,
The pressure is increased at P89.

If No in P86, Bn is "negative" or "0".
”, so after converting Bn into 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, when the answer is 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 drive wheels
When the difference is large, it is preferable to correct the integral constant in equation (5) by reducing 1, for example, in order to prevent deterioration of acceleration and engine stalling due to excessive braking.

Target slip rate SET, change of SET (P76) above P
The target slip ratios SET and SET 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 WAX calculated in step P73. As is clear from FIG. 17, in principle, the larger the maximum acceleration GWAX, the larger the target slip rates SET and SET should be. Then, the target completion rate SET, SET is
Limit values are set for each.

Here, a description will be given of how the setting relationship between the target speed gsET and SBT affects the driving sensation of the automobile 1.

■The grip forces SET and SET of the driving 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.

d) Feeling of acceleration As mentioned above, the feeling of acceleration depends on the "difference" between SET and SBT.
It changes by changing the , and since this point has already been explained in detail, a redundant explanation will be omitted.

■Smoothness of acceleration Increase SET, 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.

■ Stability during cornering Make SET smaller, that is, make SET relatively smaller than SBT. As is clear from Fig. 13, this means that the slip rate S at which the maximum grip force occurs is
In the range of =0.2 to 0.3 or less, by lowering the target slip rate, the grip force of the drive wheels is reduced, while
The lateral force is increased as much as possible to increase the bending force.

The above-mentioned characteristics (modes) of ■ to ■ can be selected manually depending on the driver's preference (switch 71 In the embodiments described above, the engine Since the brake SET is set larger than the brake SET, brake control is not performed in small slip conditions, so it can be used less frequently, and it is also possible to use brake control less frequently in the event of a large slip. The load is reduced.In addition, there is a point (S BC) between SBT and SET where slip control by brake is discontinued.
Since the brake pressure is sufficiently reduced when the brake control is stopped, sudden torque fluctuations are less likely to occur. Of course, in the present invention, the target delivery rates for the engine and the brake can also be set to the same value.

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

■Acceleration requests can be detected by checking the accelerator depression speed, the operation state of the mode selection switch 71, the amount of accelerator depression, the downshift operation of the transmission 8, the acceleration of the vehicle body, etc.
This can be done by looking at appropriate parameters such as the vehicle speed pattern (particularly the degree of increase in vehicle speed).

Alternatively, an acceleration request may be detected before entering the slip control, and the brake control ratio may be corrected to increase after starting the slip control in response to the acceleration request. In this case, in order to perform correction to increase the brake control ratio more quickly, set the target full rate SET in P9 and PIO.
It is also possible to set the ``difference'' between SET and SET to be small from its initial value. Of course, this SBT and SE
The degree to which the "difference" from T is reduced can be adjusted depending on the degree of acceleration request.

(2) It is preferable to adjust the generated torque of the engine 6 by changing and controlling the factors that most affect the output generated by the engine. That is, it is preferable to adjust the generated torque by so-called load control, and in the case of an Otto type engine (for example, a gasoline engine), by adjusting the air-fuel mixture amount, and in the case of a diesel engine, the amount of fuel injection can be adjusted by iA! It is preferable to do so. 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 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, and in this case, the generated torque may be adjusted by adjusting the power supplied to the motor.

(Mystery) 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 even if all four wheels are driving wheels. good.

■In order to detect the slippage condition of the drive wheels, it is possible to directly detect the rotation speed of the drive wheels as in the example, but it is also possible to predict the slippage condition according to the condition 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, the prediction of the slipping state of the drive wheels can be made even more appropriate by automatically detecting or manually inputting atmospheric temperature levels, rain, snow, ice burns, and other road surface conditions. You can also do it.

■Brake hydraulic pressure circuit and sensors 64 and 65 in Figure 2.
66 can utilize the existing SBA (anti-brake lock system).

■In order to increase the control ratio by the brakes, it may be done by discontinuing the slip control by the engine.
Also, when performing slip control with a certain target value,
This may be done by changing the control amount for the deviation from this target value, or by changing the target value itself (the control amount or target value may be changed for at least one of the brake and the engine). . In short, an appropriate method can be used as long as it is possible to change the ratio between the reduction in torque generated by the engine and the amount of braking by the brakes, which contributes to reducing the rotational torque of the drive wheels, between when an acceleration request is made and when there is no acceleration request. may be adopted.

(Effects of the Invention) As is clear from the above description, the present invention is effective in controlling the slippage of the driving wheels by utilizing both the application of braking force by the brake and the reduction in torque generated from the power source. It is possible to obtain good acceleration response while optimizing the balance between

[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. FIG. 5 is a graph schematically showing a control example of the present invention. 6 to 11 are flowcharts showing control examples of the present invention. Figure 7FS12 is a graph showing the characteristics of throttle opening relative to accelerator opening when slip control is not performed. 7fS Figure 13 is a graph showing the relationship between the grip force of the drive wheels and the lateral force, as well as the relationship between the slip rate and the coefficient of friction against the road surface. Figure 7514 is a graph showing correction values when correcting the slip rate at the start of slip control according to the steering angle. FIG. 15 is a graph showing the optimum throttle opening corresponding to the maximum acceleration 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 showing a state in which a correction is being made to increase the brake control ratio (reduction of the brake control target delivery rate SBT) when there is a request for acceleration. FIG. 19 is an overall configuration diagram of the present invention. 2. Vehicle 2.3: Front wheel (driving wheel) 4.5: Rear wheel (driven wheel) 6: Engine (power source) 7: Clutch 8: Transmission 13 Throttle valve 14 Nisro torque 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 (Driver wheel rotation speed) 67: Sensor (accelerator opening) 68: Sensor (handle steering angle) 69 Near accelerator 0: Handle 71: Mode switch for acceleration request selection S■1 to SV4: Electromagnetic opening/closing valve U: Control unit 2nd Figure 12 Handle f Hakama Figure 13 S (heart"11#) Figure 15 MAX Figure 16 Figure 17 MAX Figure 18 t+ t2 t3t4ff

Claims (3)

[Claims] (1) In an automobile slip control device that prevents excessive slip of the drive wheels against the road surface by controlling the torque applied to the drive wheels, the torque generated by the power source that is the torque generation source is adjusted. braking force adjusting means for adjusting the braking force of the drive wheel brake; slip detection means for detecting the slip state of the drive wheel with respect to the road surface; slip control means that performs slip control by reducing the generated torque of the power source and applying braking force to the driving wheels by operating the generated torque adjusting means and the braking force adjusting means when the slip of the driving wheel is equal to or greater than a predetermined value; acceleration detection means for detecting a driver's request for acceleration; correction means for correcting the slip control by the slip control means in a direction that increases the ratio of the slip control by the brake when there is a request for acceleration; An automobile slip control device comprising: (2) In claim 1, the slip control means performs slip control by reducing the generated torque and applying braking force only when the slip of the drive wheels is large, and when the slip of the drive wheels is small. Slip control is performed only by adjusting the generated torque without applying braking force. (3) In claim 1 or 2, the slip control means performs slip control so that the magnitude of the slip of the driving wheels becomes a target value, and the correction means is adapted to perform the slip control so that the magnitude of slip of the driving wheels becomes a target value, and the correction means This is designed to lower the target value for brake slip control when there is a problem.