JPS63137034A - Slip control device for vehicle - Google Patents

Abstract

PURPOSE:To prevent a large slip from occurring on driving wheels from the beginning of the start time by setting a slip control means to decrease the torque applied to driving wheels in advance if the road surface condition is slippery. CONSTITUTION:An engine 6 as a power source is mounted in front of a vehicle 1, and the torque generated by this engine 6 is transmitted to wheels. The engine 6 is constituted so that the generated torque is changed by a change of the intake air quantity and the intake air quantity is adjusted by a throttle valve 13. The throttle valve 13 is controlled to be opened or closed electromagnetically by a throttle actuator 14. In addition, electromagnetic type liquid pressure control valves 30, 31 as a braking force control means are connected to hydraulic pipes 28a, 29a of brakes 21, 22 for front wheels serving as driving wheels.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vehicle 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 Unexamined Patent Application Publication No. 58-16948 or
There is one shown in Publication No. 6662.

Both of the technologies disclosed in these publications reduce the torque applied to the drive wheels by using the brake to apply braking force to the drive wheels and by reducing the torque generated by the engine itself. It has become. 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. In addition, in the method disclosed in Japanese Patent Application Laid-open No. 60-56662, when the slip of only one 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, while When the slip of both drive wheels is 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 described above is started on the premise that -d large slip has occurred in the drive wheels.

However, once a large slip occurs in the drive wheels, especially when starting, the large slip will seriously damage the road surface on snowy or muddy roads, and the block pattern of the drive wheels will become covered with snow, etc. Even if slip control is performed after that, it is likely that a situation will occur in which a smooth start will not be possible, and in extreme cases,
There are even cases where the vehicle becomes stuck, making it impossible to start.

The present invention was made in consideration of the above circumstances, and
It is an object of the present invention to provide a slip control device for an automobile that enables more reliable starting.

(Means for Solving Problems 1) In order to achieve the above-mentioned object, in the present invention, when the road surface condition is slippery, the slip control means is set to a preset state, that is, the torque applied to the drive wheels is set in advance. The operating condition is such that large slips do not occur in the drive wheels from the initial stage of starting the vehicle. Specifically, the 19th
As shown in the figure, a slip control system for an automobile is equipped with a slip control means that prevents the drive wheels from slipping excessively on the road surface by controlling the torque applied to the drive wheels. A road surface condition detection means for detecting the slip control means; and a preset means for presetting the operation of the slip control means so that when the road surface is slippery, the torque applied to the drive wheels is reduced at least at the time of starting. be.

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

±hi' 112 and 1 In Fig. 1, a car 1 has left and right front wheels 2 which are 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 passes through a clutch 7, a transmission Ja8, and a differential gear 9, and then is transmitted to the left and right drive shirts) 10.11. The power is transmitted to the left and right front wheels 2.3 as driving wheels.

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

The engine 6 as a power source has its intake passage 12
Load control, that is, control of generated torque, is performed by a throttle valve 13 disposed in the engine. More specifically, the engine 6 is a gasoline engine, and the generated torque changes depending on the change in the intake air amount, and the intake air amount is adjusted by the throttle valve 13. Then, the throttle valve 13 is operated by the throttle actuator 14.
Opening and closing is controlled electromagnetically. Note that the throttle actuator 14 may be constituted by, for example, a DC motor, a step motor, or an appropriate device 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. 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.
i? 28a is connected to (the wheel cylinder of) the right front wheel brake 22, and the branch y-zsb is connected to the left rear wheel brake 23. In addition, the brake pipe 29 extending from the discharge port 27b has two branch pipes 29a and 29 on the way.
b, and the branch pipe 29a is the left front wheel brake l/- key 2.
1, and a branch pipe 29b is connected to the right rear wheel brake 24. In this way, the brake piping system is of the so-called two-system X type. Branch pipes 28a and 29 for brakes 21 and 22 for front wheels, which are driving wheels.
An electromagnetic hydraulic pressure control valve 30 or 31 as a braking force adjusting means is connected to a. Of course, the brake fluid pressure generated in the mask cylinder 27 depends on the amount (depression force) of the brake pedal 32 by the driver.

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

The piston 42 is constantly biased 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).

When braking using this hydraulic pressure control valve 30 (31) (during sleep-7 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.

The opening and closing of each of the valves 5VI-3V4 is controlled by a brake control unit (UB), which will be described later. Brake fluid pressure status to brakes 21 and 22 and each valve SV
The operational relationship with I to SV4 is summarized in the following table.

(Blank below) Control unit/unit components' In Fig. 1, U is a control unit, which can be roughly divided into the aforementioned brake control unit) UB, a throttle control unit UT, and a slip control unit. It consists of a control unit US. The control unit UB controls the opening and closing of each SS jib VI-SV4 as described above based on the command signal from the control unit US. In addition, based on the command signal from the throttle control unit (UTji) control unit US,
Drive control of the l-le actuator 14 is performed.

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 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.

Note that the control unit (US) is basically a CPU,
Equipped with FILM, RAM, CLOCK, 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, 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: Rotation speed of driving wheels (2, 3) WL: Rotation a of driven wheels (4) (vehicle speed) The throttle control unit UT provides feedback to the throttle valve 13 (throttle actuator 14) so that the target throttle opening is achieved. It is supposed to be controlled. During this throttle control, when slip control is not performed, control is performed so that the target throttle opening corresponds to the operation amount of the accelerator 69 operated by the driver at a ratio of 1:1, and the accelerator opening at this time is FIG. 12 shows an example of the correspondence relationship between and the throttle opening degree. In addition, the control unit UT controls the first
Throttle control is performed so that the target throttle opening degree n calculated by the control unit US is achieved without following the characteristics shown in FIG.

Throttle valve 1 using control unit hUT
In the embodiment, the feedback control No. 3 is performed by PI-FD sub-control in order to compensate for fluctuations in the response speed of the engine 6. That is, when controlling the slip of the driving wheels.

The opening degree of the throttle valve 13 is controlled by P I -F D 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 -FP (WDn-WDr+-1) -F D (Wien -2X WOn-1+ WD
JI-2) Fist... (2) WL: Number of revolutions of driven wheels (4) WD: Number of revolutions of driving wheels (2, 3) KP: Constant of proportionality: Integral constant FP: Constant of proportionality FD: Differential constant S ET: Target slip rate (for throttle control) As shown in equation (2) above, the throttle opening degree Tn is feedback-controlled on 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 above-mentioned control unit) UT
The sub-control is shown in Figure 3 as a block diagram, and ``S''' shown in Figure 3 is an ``operator'', and each suffix rnJ, rn-1'' indicates the current and one time. Shows the value of each signal at the previous sampling time.

During brake control slip control, the control unit hUB
The rotation (slip) of the left and right drive wheels 2.3 is feedback-controlled independently to a predetermined target slip rate SBT. 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 SET of the brake is set larger than the target slip rate SET of the engine, as will be described later. In other words, the slip control of this embodiment increases or decreases the engine output to a predetermined 5ET (WET), and also increases or decreases the engine output to a larger SBT (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 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 (WD!l -WDn-1) -F D
(WDr+ -2X WDn-1+ WDn-2) Association-
Fist (5) KI: Integral coefficient KD: Proportional coefficient FD: Derivative coefficient When the above Bn is larger than 0 (“positive”), the brake fluid pressure is increased, and when it is less than θ, it is reduced. This increase/decrease in brake fluid pressure is controlled by valves SV1 to SV1 as described above.
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 W) 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 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 outline of slip control The overall outline of slip control by the control unit U will be described with reference to FIG. 5. The meanings of the symbols and numerical values shown in FIG. 5 are as follows.

S/C Nislip control area E/G: Slip control by engine B/R Slip control by Nibrake F/B: Feedback control 0/R: Open loop control R/Y + recovery control B/A: Backup control A/S: ! l Impact secondary control = 0.2 Slip rate at the start of Nislip control m (SS) S = O, 17: Target slip rate by brake (S BT
) S = 0.09 Slip rate when stopping slip control by Nibrake (S Be) 3 = Q, 06: Target slip rate by engine (S Be)
ET) S = 0.01 to 0.02: Slip rate in the range where buffer control is performed s = o, o i or less: Slip rate in the range where backup control is performed The information is based on data obtained from driving.

Then, S = 0.01 and 0.02 to perform buffer control A/S.
, and the slip rate S=0.09 at the time of stopping the slip control by the brake are respectively unchanged in the embodiment.

On the other hand, the target slip rate SET due to the brake, the target slip rate SET due to the engine, and further the slip rate SS at the start of slip control are changed depending on the road surface condition, etc., and FIG. 5 shows an example of ro, 17
J, ro, 06J A Rui indicates 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 Figure 13).
In this way, the reason why the slip rate at the start of slip control is set to 0.2 is so that the actual slip rate when this maximum grip force is obtained can be determined, and this maximum grip force Depending on the slip rate at the time of occurrence, 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 1-slip ratio. Moreover, the broken line in FIG. 13 shows the relationship between grip force and lateral force when using normal tires.

(Left below) Based on the above, FIG. 5 will be explained as time goes on.

■to-tl Since the slip rate S does not exceed S = 0.2, which is the slip control starting condition, slip control is not performed. In other words, when the slip of the drive wheel is small, acceleration is not performed without slip control. (driving using greater grip power). 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.

(t1-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 slip rate of the brake (S = 0.17) is larger than the target slip rate of the engine (S = 0.06), the brake is not 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.

(2) t2~1+ (Recovery control m) 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) (open loop control). At this time,
The maximum acceleration G WAX at the time S=0/2 (t2) is determined, and the maximum IL of the road surface (maximum grip force of the driving wheels) is estimated from this G WAX. Then, throttle valve 1 is adjusted so as to generate maximum grip force for the drive wheels.
3 is held for a predetermined time as described above. In this control, the feedback control cannot respond in time because the slip converges rapidly, and the vehicle body acceleration G immediately after the slip converges.
This is done to prevent people from becoming depressed. For this reason,
When slip convergence is predicted (S=0.2 or lower)
As described above, by securing a predetermined torque in advance, acceleration performance is improved.

The optimum throttle opening tiTVo for realizing the torque applied to the drive wheels that can generate the maximum grip force is theoretically determined from the torque curve of the engine 6 and the gear ratio. The decision should be made based on the map shown below. This map was created using 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.
, and the optimum throttle opening TVo is corrected for other gears.

■ t4 to t7 (Backup control, buffer system w) Backup control is performed in order to deal with when the slip rate S decreases abnormally (open loop system m), that is, when S<0, 01. In order to stop feedback control and open the throttle valve 13 in stages, and when the slip rate is between 0.01 and 0.02, to smoothly transition to the next feedback control, Buffer control is performed (t4~E5 and t6~
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 system m@ calculation and the throttle opening degree T1 obtained by the backup control calculation are proportionally adjusted by the current slip rate So. The throttle opening degree To is obtained by distributing the throttle opening.

■t7 to t8 By performing the control from t7 to t7, there is a smooth transition to slip control using only the engine.

■Since the accelerator 69 is fully closed by the driver after t8, the slip control is stopped. At this time, the throttle valve 13
Even if the degree of opening of the accelerator is left to the driver's will, there is no risk of slipping again because the torque has been sufficiently reduced. This is also carried out when the target throttle opening due to slip control becomes smaller than the throttle opening determined in FIG. 12, which corresponds to the accelerator opening operated by the driver.

Here, in order to prevent excessive slipping of the drive wheels at the time of starting, in the embodiment, when the road surface condition is slippery, automatic brake control applies a predetermined braking force to the drive wheels 2.3 in advance. This is how I do it. Further, whether the road surface condition is slippery or not is determined by checking whether any one of the wheels 2, 3, 4, 5 is locked during braking at a low vehicle speed.

Details of slip control (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 for this purpose. Note that in the following explanation, P indicates a step.

After the system is initialized at PO, preset control, which will be described later, is performed at Pl. Then, P
In step 2, it is determined whether or not the device is currently stuck (as in 8, where the device is stuck in mud or the like and cannot move). This determination is made by checking whether a stack flag, which will be described later, is set. P
When the determination in step 2 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. This P
When it is determined NO in step 4, it is determined in step P5 whether or not slip control is currently being performed.
This is done by checking whether the slip control flag is set. When the determination in P5 is NO, it is determined in P6 whether or not a slip has occurred that requires slip control. This determination is made by checking whether slip flags for the left and right front wheels 2.3, which will be described later, are set. When the determination in P6 is No, the process moves to P7 and the slip control is stopped (normal driving).

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

Subsequently, in P9, the initial value of the target slip rate SET for the engine (throttle) (0.06 in the example) is set, and in PIO, the initial value of the target slip rate SET for the brake (0, 17 in the example) is set. ) is set. After this, brake control using pH and engine control using PI2 are performed for slip control, as will be described later. Note that the initial value settings in P9 and PIO are made from the same viewpoint as in P76, which will be described later, based on the maximum acceleration G MAX 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.

When the determination in P4 is YES, it means that slip control is no longer necessary, and the process moves to PI3. This PI
At 3, the slip control flag is reset at 0, then,
Engine control is stopped at PI3, and brake control is performed at PI3. It should be noted that this brake control in PI3 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 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, in P22, slip detection processing, which will be described later, is performed, and then, in P23, throttle control is performed.

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. If YES in P24, control of the throttle valve 13 is selected for slip control, that is, control that achieves a predetermined target slip rate SET without following the characteristics shown in FIG. 12. 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 P28. This P2
5. After P26, control is performed in P27 to achieve the target throttle opening (P68 described later).
．． Control according to P2O, P71 or control according to the characteristics of the $12 diagram w).

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

First, in P31, it is determined whether the clutch 7 is completely connected. If YES is determined in P31, it is assumed that the stack is not in progress, and the stack flag is reset in P32.
3, the current vehicle speed is low, for example 6.3 km.
It is determined whether or not the value is smaller than /h.

If NO is determined in P33, a correction value α for slip determination is calculated in accordance with the steering angle in P34 (see Fig. 14), and then in P35, the left front wheel as the left driving wheel is calculated. The slip rate of 2 is equal to the 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. The above correction value α is based on the rotation difference between the inner and outer wheels during turning (especially the rotation difference between the driving wheel and the driven wheel).
It is set taking into consideration.

After P36 or P37, P38, P39, P2O
In , the slip flag for the right front m3 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.

When 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 partially).

In this case, the process moves to P51, and it is determined whether the rotational speed difference between the left and right front wheels 2 and 3 as driving wheels is small (for example, whether the rotational speed difference is 2 km/h or less when converted to vehicle speed). If it is determined No in P51,
At P52, it is determined whether stack control is currently in progress. When the determination is NO in P52, it is determined in Pb0 whether the rotation speed of the right front wheel 3 is greater than the rotation speed of the left front wheel 2. When Pb0 is determined as YES, the rotation speed of the right front wheel 3 is 1.5 times the rotation speed of the left front wheel 2.
It is determined whether or not it is greater than five times. Y at this Pb0
When it is determined to be ES, a stack flag is set at Pb6. Conversely, when the determination is No at Pb0, it is assumed that the stack is not in progress, and the processes from P32 onwards 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 it is ES, it will move to Pb6, and if it is No, it will move to P32.

After Pb6, the vehicle speed is 6.3 km at P57.
It is determined whether the value is larger than /h. If YES in 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). Also, NO on P57
In this case, the target rotation speed of the front wheels 2.3 is uniformly set to 10 km/h in P59. YES on P51
In this case, the brake is slowly released at P2O.

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

At P61, it is determined whether the slip has transitioned to a convergence state (or not after passing the second point in FIG. 5). If NO in Pa1, 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 at Pa3 whether the slip rate S of the right front wheel 3 is greater than 0°2. When the answer is No in Pa3, it is determined in Pa4 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. When YES in Pa4, the current slip rate is calculated in Pa5 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, when Pa4 is No, the current slip rate is calculated according to the driving wheel with the larger slip rate among the left and right front wheels 2.3 (select high).In addition, when P62 and Pa3 are NO Also in this case, the process shifts to Pa6.

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 Pa5 and Pa6, it is determined in Pa7 whether the current slip rate S is greater than 0.02. When YES in Pa7, the throttle valve 13 is feedback-controlled for slip control in P68. Of course, at this time, the throttle valve opening degree (Tn) is set to realize the target slip rate SET set in Pa5 and Pa6 or changed in P76, which will be described later.

When the answer is NO in Pa7, it is determined in Pa9 whether the current fill rate S is greater than 0.01. If YES in Pa9, the buffer control described above is performed in P2O. Also, if Pa9 is NO, P71
In this step, the backup control described above is performed.

On the other hand, when Pa1 is YES, the process moves to PI2, and it is determined whether a predetermined time (time for performing recovery control, 170 msec as described above in the embodiment) has elapsed after the slip convergence. When PI2 is No, processing from P73 onward is performed to perform recovery control. That is, first, in P73, the maximum acceleration G WAX of the car 1
is measured (at time t2 in Figure 5). Next, in P74, the optimum throttle opening degree Tv□ is set so that this G MAX can be obtained (see FIG. 15). Furthermore, P
At 75, P7 is determined depending on the current gear position of the transmission 8.
The optimum throttle opening Tv□ at 4 is corrected. That is, since the torque applied to the drive wheels differs depending on the difference in gear position, the optimal throttle opening TVQ for a certain reference gear position is set in P74, and this difference in gear position is corrected in P75. be. After this, in P76, the friction coefficient of the road surface is estimated from the G WAX in P73, and the target slip rate SET and SBT for slip control by the engine (throttle) and brake are changed. Note that how to change the target slip rates SET and SBT will be described later.

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

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

First, in Pa1, it is determined whether or not it is currently stacked. If Pa1 is NO, then in Pa2,
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 a depending on the vehicle speed (the higher the vehicle speed, the larger it becomes). 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 P82.83 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).
), then 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 pressure increasing direction is the increasing pressure direction, assuming that the increasing pressure direction of the brake is positive and the pressure decreasing direction is negative.

When P86ffiYES (7), at PO2, B
It is determined whether n>BLM. YES at PO2
In this case, after setting Bn to the limit value BLM,
2, the pressure of the right brake 22 is increased. Also,
When NO at PO2, the pressure at PO2 is increased using the Bn value set at 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 F93 are when depressurizing the right brake 22, and PO2, P88, PO
2 processing is supported.

After PO2 and P93, the process moves to P94, and pressure increase or decrease processing is performed for the left brake 21 in the same way as for the right brake 22 (process corresponding to P84 to P93).

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

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

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

This corresponds to PI in FIG.

First, it is determined in the PIOI whether the current vehicle speed is low, for example, 10 km/h or less. This P
When the IOI determination is YES, P2O3 determines whether or not braking is currently in progress, and this determination determines YES.
In this case, it is determined in P2O3 whether at least one of the wheels 2, 3, 4, 5 is locked. This P
If the determination in 2O3 is YES, a preset flag is set in P2O3.

Thereafter, in P105, it is determined whether the preset flag is set. With this Pi05 determination, Y
When in ES, at least a small amount of brake pressure is applied to the drive wheels in order to prevent a large slip from occurring in the drive wheels during the next start in P2O3. Also, P2O3
If the determination is NO, automatic brake control, that is, a small amount of brake pressure is not applied to the drive wheels in advance, is not performed.

When the determination is No in P101, there is a strong possibility that the vehicle will continue to run, so P2
After clearing the preset flag at O3, PI 0
5 and subsequent processes are performed. In addition, if it is determined No in P102 or PI 03, proceed to P102.
5 and subsequent processes are performed.

(The following is a blank space) Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

■In addition to engine control and brake control, the torque applied to the drive wheels can be adjusted by adjusting the engagement state of the clutch 7, or by changing the gear ratio of the transmission 118 (especially effective in the case of a continuously variable transmission). This can be done by any one or a combination of appropriate components that can adjust the torque applied to the drive wheels.

(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 a complete 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. It is preferable. However, this load control is not limited to this, and may be carried out by adjusting the ignition timing in the case of an engine with a complete engine, or by adjusting the fuel injection timing in the case of 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.

(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 state of the vehicle body7! i (acceleration), load capacity, etc. can be considered. In addition, the above-mentioned slipping state of the drive wheels can be detected even more appropriately by automatically detecting or manually inputting high/low atmospheric temperature, road surface conditions such as rain, snow, ice burns, etc. You can also do it.

■Brake fluid pressure control circuit and sensor 64.6 in Figure 2
5.66 can utilize existing ABS (anti-brake lock system).

■The preset torque reduction operation to the drive wheels is
This may be done by opening the throttle smaller or later than the accelerator opening (reducing the throttle gain), or by reducing the connection speed of the clutch 7, or other appropriate means may be adopted.

(Effects of the Invention) As is clear from the above description, the present invention prevents a large slip from occurring in the drive wheels from the initial stage of starting.
It is possible to start more reliably.

[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 18 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. FIG. 17 is a graph showing an example of a map used when determining the target slip rate. FIG. 19 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 (drive wheel rotation speed) 66: Sensor (Number of rotations of driven wheels) 67: Sensor (accelerator opening) 68: Sensor (handle steering angle) 69 Near accelerator 0: Handle 5VI-3V4: Electromagnetic opening/closing valve U: Control unit Fig. 2 Fig. 10 Fig. 12 Agepur 1 (-1 Figure 14 hand l and Fukuguchi angle Figure 13 S snoring JP 1 Figure 15 MAX Figure 16 (Ji-kashi 6) MAX

Claims (1)

[Claims] (1) In a slip control device for an automobile equipped with a slip control means that prevents excessive slip of the drive wheels on the road surface by controlling the torque applied to the drive wheels, the slip control device detects the slipperiness of the road surface. The vehicle is characterized by comprising: a situation detecting means; and a presetting means for presetting the operation of the slip control means so that when the road surface is slippery, the torque applied to the drive wheels is reduced at least at the time of starting. Automotive slip control device.