JPS6331871A - Slip controller for automobile - Google Patents

Abstract

PURPOSE:To make slip control afterward into an optimum something, by making the slip control by a slip controlling device so as to be started at a time when size of each slip of driving wheels becomes more than the size capable of securing the maximum grip force. CONSTITUTION:In this controller, 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, whereby 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 desired value. And at this time, when size of the driving wheel slip becomes more than the size at time of capable of securing the maximum grip force, the slip control done by the slip controlling device C is made so as to be started by a slip control starting device D.

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 the key to effectively obtaining the propulsive force of the vehicle, and is also effective in terms of safety by preventing spins. . In order to prevent the drive wheels from slipping excessively,
All that is needed is to reduce the torque applied to the drive wheels, which causes slip.

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 looks like this. 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.

(Problems to be Solved by the Invention) One problem is when to start slip control of the driving wheels. Particularly, when the magnitude of the slip of the drive wheels is set to a certain target value during slip control, the manner in which this target value is set has a large effect on the driving condition, such as acceleration or stability. Even if this target value remains the same, the above-mentioned driving condition will change depending on the relative frictional relationship between the road surface and the tires.

The present invention was made in consideration of the above circumstances, and
13H drive wheel slip control! It is an object of the present invention to provide a slip control device for an automobile that can optimally perform subsequent slip control by optimally selecting the magnitude of slip of a drive wheel when fj is adjusted.

(Means and operations for solving the problem) In order to achieve the above-mentioned object, in the present invention, the magnitude of the slip of the drive wheel when starting the slip control of the drive wheel is
The size should be larger than that at which maximum grip force is obtained.

In this way, in the present invention, the magnitude of slip when slip control is started is set to be equal to or greater than the magnitude when maximum grip force is obtained. The target value of the slip size can be optimally set in consideration of this maximum grip force size. For example, if you focus on acceleration,
If you set the target value for slip control near where the maximum grip force is obtained, and if you place emphasis on stability (increase the lateral force of the tire), you can set the target value to a value smaller than when the maximum grip force is obtained. It would be a good thing to do.

Note that the amount of slip when the maximum grip force is generated varies depending on the relative slipperiness of the tire to the road surface. Since this information can be determined by manual input, the magnitude of the slip of the drive wheels at the start of slip control can be set based on this estimation or the slip situation at the time of manual input. The estimated or manually input hypothetical slipperiness of the road surface can then be determined by measuring the amount of slip when the driven wheels (vehicle body) reach their maximum acceleration after the start of slip control. This means that the correction will be made accurately according to the slipperiness of the area.

Specifically, the present invention is configured as shown in FIG. That is, in an automobile slip control device that prevents excessive slip of the driving wheels on the road surface by controlling the torque applied to the driving wheels, the present invention includes a torque adjustment means for adjusting the torque applied to the driving wheels; , a slip detection means for detecting a slip state of the driving wheels with respect to a 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 driving wheels reaches a predetermined target value. and a slip control start means for starting slip control by the slip control means when the magnitude of slip of the driving wheels exceeds the magnitude at which maximum grip force can be obtained.

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

Overview of overall configuration In Fig. 1, a car l has left and right front wheels 2 which are drive wheels.
．． 3 and left and right rear wheels 4.5 serving as driven wheels. An engine 6 as a power source is installed at the front of the automobile 1, and the torque generated by the engine 6 passes through a clutch 7, a transmission a8, and a differential gear 9, and then is transmitted through 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, 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 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 to 5 has 2 brakes, 22.23
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 includes a wheel cylinder, and the brake pad is moved 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.

Brake Hydraulic Pressure Control Circuit As shown in FIG. 2, each of the hydraulic pressure control valves 30, 31 has a cylinder 4 and a piston 42 slidably inserted into the cylinder 41. This piston 42 allows the inside of the cylinder 41 to be expanded into a variable Jar 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 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 (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 (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 of the valves SVI to SV4 is controlled by a brake control unit (brake control unit) UB, which will be described later. Brake fluid pressure status to brakes 21 and 22 and each valve 5V
The operational relationship with I-3V4 is summarized in the following table.

ゝ＼ Configuration overview of control unit i1 In the diagram, U is a control unit, which is roughly divided into the aforementioned brake control unit UB, as well as a throttle control unit UT and a slip control control unit US. There is. Based on command signals from the control unit, the control unit UEt*, and the control unit US, the opening and closing of each valve SVI to SV4 is controlled as described above. Further, the throttle control unit UT performs drive control of the throttle actuator 14 based on a command signal from the control unit US.

The slip control control unit (US) is constituted by a digital computer, more specifically a microcomputer. this control unit)
Signals from each sensor (or switch) 61 to 68 are input to 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 are the left and right front wheels as driving wheels? , 3 rotation speeds are detected. 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. Senna 68 is 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 is basically a CPU,
Equipped with ROM, RAM, CLOCKt, etc.
In addition to having an input/output interface, it also has an A/D or D/A converter depending on the input signal and output signal, but in these respects it is no different from a normal one when using a microcomputer. Therefore, a detailed explanation of part 1 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 Rotation speed WL of the two driving wheels (2, 3): Rotation speed (vehicle speed) of the driven wheel (4) The throttle control control unit UT gives 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 (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. In addition, control unit 0 controls the first control unit during slip control.
Without following the characteristics shown in FIG. 2, the throttle is controlled so as to reach the target throttle opening Tn calculated by the control unit (US).

Throttle valve 1 using 0 control units
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, 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 -5ET -5ET -F P (WDn -WDn-1) -F D C
WDn-2X WDn-1+ Wlln-2)・φ・
(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 full rate (throttle For control) As shown in the above equation (2), the throttle opening degree Tn is feedback-controlled to the rotation speed of the driving wheels so that it becomes a predetermined target slip rate SET. In other words, as is clear from equation (1) above, the throttle opening is determined by the target drive wheel rotation speed WE.
T is controlled so that it satisfies the following equation (3).

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

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

In this embodiment, the target slip rate SBT of the brake is set to be 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 increases or decreases the engine output to a larger 5BT (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 -F P (WDn -WDn-1) -FD (W
Dn - 2 When the pressure is 0 or less, the pressure is reduced. This increase/decrease in brake fluid pressure is controlled by the valve 5VI-
This is done by opening and closing 3V4. In addition, increase/decrease in brake fluid pressure and adjustment of speed are performed using the valves S■1 to S.
This is done by adjusting (duty control) the ratio of opening/closing time (duty ratio) of V4, 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 knee 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 slip control R An overall outline of the slip control by the control unit U will be described 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: Feed bank control 0/R: Open 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 ('5S) S = 0.17: Target slip rate by brake (S ET
) S = 0.09 Slip rate when stopping slip control by Nibrake (S 5C) S = 0, 06: Target slip rate by engine (S
ET) S = 0, 01 to 0, 02: Slip rate in the range where collision control is performed s = o, oi or less Slip rate in the range where backup control is performed This is 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, 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 the slip control is set as large as 0.2 is so that the actual slip rate when this maximum grip force can be obtained can be determined. Depending on the slip rate at the time of force generation, the target slip rate by the engine and brake SET, S
ST is corrected.

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.

■t □ -t 1 Since the slip rate S does not exceed S=0.2, 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. , (2) t1 to t2 Slip control is started and the slip rate is equal to or higher than the brake-based slip control stop point (s=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 flattening rate (S = 0.17) of the brake is larger than the target flattening rate (S = 0.06) of the engine, the brake is pressurized when there is a large slip (S > 0, 17). However, when there is a small slip (S<0, 17), the brake is not pressurized and the slip is controlled only by 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 slip converges (S<0.2) (oven loose control). At this time,
The maximum acceleration G MAX at the time S=0/2 (t2) is determined, and the maximum color of the road surface (maximum grip force of the driving wheels) is estimated from this G MAX. 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 driving wheels/＼ that can generate the maximum grip force mentioned above can be theoretically determined from the torque curve of the engine 6 and the gear ratio. For example, the decision is made based on a map as shown in Figure 15. This map was created by an experimental method, and G WAX is 0.1.
When it is 5 or less and 0.4 or more, it is set to a predetermined constant value, taking into account the measurement error of G MAX. Note that the map shown in FIG. 12 is for a certain gear position (for example, 1st gear)
This assumes that the optimum slow/torque opening TVo is corrected for other gears.

■ t4 to t7 (backup control, buffer control) In order to cope with an abnormal decrease in the slip rate S, backup control is performed (oven loop control), that is, when s<o, o i, , the feedback control is stopped and the throttle valve 13 is opened in stages. When the slip rate is between 0.01 and 0.02, 1. In order to smoothly transition to the next feedback control, buffer control is performed (t4 to L5 and t6 to t7). This backup control is performed when neither feedback control nor recovery control can cope 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 backup control is set to 0% with respect to the previous throttle opening at every 14 m5 ec of sampling time of the throttle opening.
．． It is assumed that an additional amount of 5% opening is added.

In addition, in the above-mentioned 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 based on the current slip rate So. The throttle opening degree To is obtained by doing this.

(L7 to 78) By performing control up to t7, there is a smooth transition to slip control using only the engine.

■Since the accelerator 69 was fully closed by the driver after 78, slip control was discontinued. 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.

Details of slip control (flow chart) Next, Figure 6~
The details of the slip control will be explained with reference to the 7th coachyard in FIG. It also controls the stack. In addition, 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, is set. 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.

This is done by checking whether a slip flag for the left and right wheels 2.3, which will be described later, is set.

When the determination is NO in this P6, move to Pl,
Slip control is canceled (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 SBT for the brake is set in PIO. After this, brake control is performed at Pll and engine control is performed at P12 for slip control, as will be described later. The initial values in P9 and Plo are set based on the maximum acceleration G WAX obtained in the previous slip control from the same viewpoint as in P76, which will be described later.

If YES is determined in P5, the pH shifts to the above-mentioned pH level and slip control is subsequently performed.

YES on P4 above! - When it is determined, slip control is no longer needed, and the process moves to Pl4. At Pl4, the slip control flag is reset. Next, 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 P14 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 interrupts the main flowchart in FIG. 6, for example, every 14 msec.

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 ser- and torque 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. If YES in this P24, throttle valve 13
The control is selected for slip control, that is, the control that realizes a predetermined target completion rate SET without following the characteristics shown in FIG. 12 is selected. 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, in P27, control is performed to achieve the target throttle opening (F
1a, P2O, P71 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 applied to tFa. If YES is determined in P31, it is assumed that the stack is not in progress, 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, 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.
2 plus α in P34 above (0, 2 + α). In this determination in P35, 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 F3a or P37, F3a, F3a, P2O
In , the slip flag for the right front wheel 3 is set or reset in the same manner as in P35, F3a, and P37.

If YES is determined in P33, the vehicle speed is low, and there will be a large error in calculating the slippage rate using the vehicle speed, that is, based on the formula (1). It is intended to be detected by numbers only. 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 F4a.

After P42 and F4a, 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 P51 is determined as NO, P
At b0, it is determined whether stack control is currently in progress. When the determination is No in Pb0, 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 F5a. 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 F5a, and if the answer is NO, the process goes to P32.

After F5a, the vehicle speed is 6.3km/h in P57.
It is determined whether or not it is larger than . YES on this P57
When this is determined, the target rotation speed of the front wheels 2.3 is set to be 1.25 times the driven wheel rotation speed indicating the vehicle speed (corresponding to a slip ratio of 0.2). Also, if No in P57, the target rotation speed of the front wheel 2.3 is set to 10 in P59.
It is uniformly set to km/h.

Furthermore, when YES7) at P51, the brake is slowly released at P2O.

Fig. 10 (Engine control) The flowchart shown in Fig. 10 is based on P12 in 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 slippage rate S of the right front wheel 3 is greater than 0°2. If 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]. On the other hand, if the answer is No on P64, the answer is ``Kuthai''). In addition, even if P62 and P63 are NO, P66
to move to.

The selection high in P65 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, the throttle valve 13 is feedback-controlled for slip control in P68. Of course, at this time, the throttle valve opening (Tn) is the target slip*sE'r set in P65 and P66 or changed in P76, which will be described later.
It is set to realize the following.

If NO in P67, it is determined in P6O whether the current slip ratio S is greater than 0.01. If YES at P6O, the buffer control described above is performed at P2O. Also, if P6O 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. When P72 is No, the processing from P73 onward is performed to perform recovery control. That is,
First, in P73, the maximum acceleration G MAX of the automobile 1 is measured (time t2 in Fig. 5), and then, in P74, the optimum throttle opening Tv□ to obtain this G MAX is set (15th (see figure). Furthermore, P75
At P74, the optimum throttle opening degree Tv□ is corrected according to the current gear position of the shift a8. That is,
Since the torque applied to the drive wheels differs depending on the gear position, the optimum throttle opening TVQ for a certain reference gear position is set in P74, and this difference in gear position is corrected in P75. After this, in 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 PI1 of Fig. 6.
Compatible with 8 and PI3.

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 JffBn (corresponding to the duty ratio for opening/closing control of SVI to SV4) is
Set as a function according to vehicle speed (the higher the vehicle speed, the larger the value). Conversely, if YES in P81, the limit value BLM is set as a constant value smaller than that in P82 in P83. In addition, the processing in P82 and 83 takes into account that if the Bn calculated by equation (5) above is used, the brake fluid pressure increase/decrease rate 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 or not the slippage rate S is larger than 0 or 09, which is the brake control stop point. If YES in P84, the operation speed Bn of the right front wheel brake 22 is calculated in P85 (Bn in the I-FD sub-control in Fig. 4).
). 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.

When YES (7) on P86, Bn> on P87
It is determined whether or not it is BLM. When YES in P87, after setting Bn to the limit value BLM, the pressure of the right brake 22 is increased in P89. Also, P8
If NO in step 7, the pressure is increased in step P89 using the Bn value set in step P85.

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 F93).

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.

Changing the target slip rate SET, SBT (P76) The target slip rate SET, SET of the engine and brake changed in the above P76 is based on the maximum acceleration GIIAX measured in P73, for example, as shown in Fig. 17. will be changed to As is clear from this Figure 17,
As a general rule, the larger the maximum acceleration GMAX, the larger the target slip rates SET and SBT should be.

Limit values are set for each of the target slip rates SET and SBT.

Next, we will explain how the setting relationship between the target fullness rate SET 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 friction coefficient increases 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 or higher.

■Feeling of acceleration The feeling of acceleration changes by changing the difference J between SET and SET, and the smaller this difference, the greater the sense of acceleration. 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 Make SET thicker, that is, 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 SET is made smaller, that is, SET is made relatively smaller than SBT. As is clear from Fig. 13, this means that the grip rate S =
In the range of 0.2 to 0.3 or less, by lowering the target slip ratio, the gripping force of the driving wheels is reduced, while the lateral force is increased as much as possible to increase the force for one bend.

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

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 states 5 and 3 of the clutch 7, or by changing the gear ratio of the transmission 8 (especially in the case of a continuously variable transmission). This can be done by any one or a combination of appropriate components capable of adjusting the torque applied to the drive wheels.

(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. In other words, it is preferable to adjust the generated torque by so-called load control, and in the case of an automatic engine (for example, a gasoline engine), by adjusting the mixture amount, and in the case of a diesel engine, by adjusting the amount of fuel injection. is preferred. 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.
The generated torque in this case 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, by automatically detecting or manually inputting atmospheric temperature, rain, snow, ice, etc., the prediction of the running condition of the drive wheels can be made even more appropriate. You can also.

■Brake hydraulic pressure circuit and sensor 64.64. in Figure 2.
66 can utilize the existing ABS (anti-brake lock system).

(2) The slip determination reference values (0, 2) at P35 and P38 may be changed according to G WAX at P73. In other words, since the larger G MAX is, the greater the slip rate S when maximum grip force is obtained, the larger G WAX is, the greater P35, P
The reference value at P36 may be increased. In this case, the initial reference value at P35 and P36 may be input manually.

(Effects of the Invention) As is clear from the above description, the present invention optimally sets the magnitude of the slip of the driving wheels at the time of starting slip control, and adjusts the magnitude of the slip of the driving wheels during subsequent slip control. This is preferable for accurately and optimally setting the target value.

[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 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 the slip rate at the start of slip control is corrected according to the steering wheel 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. fF! Figure J17 is a graph showing an example of a map used when determining the target completion rate. FIG. 18 is an overall configuration diagram of the present invention. 1: Automobile 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 (driving wheel rotation speed) 66: Sensor (sub 67: Sensor (accelerator opening) 68: Sensor (handle steering angle) 69 Near accelerator: Handle SVI to SV4: TL magnetic opening/closing valve U: Control unit Fig. 7 Fig. 8 - 7 convex q- Fig. 12 Handle e Midomari Figure 13 S (Muri 4') Figure 15 MAX Figure 16 Figure 1 Pe1 no fP (Sl Figure 17? MAX Procedural amendment (method) % formula % 1 case display 1986 patent Application No. 175662 2 Name of the invention Automotive slip control device 3 Relationship to the case of person who makes amendments Patent applicant name (313) Mazda Motor Corporation 4 Agent Address: 105 (508) 1801 (Shipping date: 9, 1988) 30th of May) 6. Delete "and Figure 23" from the 7th line from the bottom of page 52 of the specification subject to amendment 7.

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 slip control start means for starting slip control by the slip control means when the magnitude of the slip of the driving wheels exceeds the magnitude at which maximum grip force can be obtained. Slip control device for automobiles.