JPS6331830A - Slip controller for vehicle - Google Patents

Abstract

PURPOSE:To compromise the stability during steady state traveling with increased acceleration, by providing means for modifying a slip control target level in the direction for producing the maximum grip force of a drive wheel when compared with that during steady traveling upon demand of acceleration. CONSTITUTION:Means A for regulating torque to be applied onto a drive wheel by regulating the torque being produced through control of an engine throttle torque and the brake force is provided. Means B for detecting the slip condition of the drive wheel against a pavement is also provided, and the torque regulation means A is controlled by a slip control means C that the slip of the drive wheel being detected by said detecting means B has a predetermined target level. Furthermore, means D for detecting a demand for acceleration from a driver is provided so as to modify said target level in the direction for producing the maximum grip force of the drive wheel when compared with that during steady traveling upon detection of the demand of acceleration.

Description

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

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

A conventional slip control of this type is disclosed in Japanese Patent Laid-Open No. 16948/1983. The technology disclosed in this publication uses the application of braking force to the drive wheels by the brake and the reduction of the torque generated by the engine itself to reduce the torque applied to the drive wheels. There is. More specifically, JP-A-58-1694
In the No. 8 publication, when the slip of the drive wheels is small, only the braking of the drive wheels is performed, but 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 applied. It is designed to lower the An example of when the drive wheel slip control is performed is during acceleration. That is, it is disclosed that large slips of the drive wheels that occur during acceleration are prevented.

(Problems to be Solved by the Invention) In slip control, one problem is how to control the slip of the drive wheels to what value. In other words, in order to satisfy acceleration performance, it is sufficient to set the target value of slip control so as to obtain the maximum grip force of the drive wheels, but in this case, the lateral force of the drive wheels becomes small and stable during steady driving. In addition to becoming unfavorable in terms of securing sex,
During steady driving, the drive wheels do not have enough extra grip, so when you try to accelerate, you will not be able to get a sufficient feeling of acceleration. On the other hand, if the target value of slip control is set in accordance with steady running, sufficient acceleration performance will not be obtained.

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 can simultaneously satisfy both stability and acceleration during steady running.

(Means for solving the problem 1) In order to achieve the above-mentioned object, in the present invention, when there is a request for acceleration, the target value of the slip control is set to be lower than that during steady running.
The direction should be changed so that the maximum grip force of the drive wheels can be obtained. In other words, by changing the target value of the slip control, slip conditions suitable for both steady running and acceleration are obtained. Specifically, as shown in FIG. 18, 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, a torque adjustment means for adjusting the torque applied to the drive wheel; a slip detection means for detecting a slip state of the driving wheels relative to the road surface; an acceleration detection means for detecting an acceleration request from the driver; a slip control means for controlling the torque adjustment means so that the torque adjustment means is controlled so that the torque adjustment means is controlled so that the torque adjustment means is controlled so that the target value is changed to a direction in which the maximum friction of the drive wheels is obtained when there is an acceleration request; and.

This is a configuration with the following.

(Embodiment) An embodiment of the present invention will be described below based on the attached drawings. In the embodiment, in order to adjust the torque applied to the drive wheels by 2gI, the torque generated by the engine itself and the braking force by the brake are adjusted. This is how it is done.

Project 1 Relative (7)
．． It has four wheels: 3 and 4.5 left and right rear wheels that serve as driving wheels. An engine 6 as a power source is mounted on the front of the automobile 1, and the torque generated by the engine 6 passes through a clutch 7, a transmission 8, and a differential gear 9, and then is transmitted to left and right drive shafts 10 and 11. The power is transmitted to the left and right front wheels 2.3 as driving wheels. In this way, 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 2-5 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 2 by a force corresponding to the magnitude of the brake fluid pressure supplied to the wheel cylinder.
5, braking force is generated.

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

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

The piston 42 is constantly urged by a return spring 45 in a direction in which the volume of the variable volume chamber 43 increases. Further, a check valve 46 is integrated into the piston 42. This check 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 in the middle, and one branch? 48R is 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 22 hUB, 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.

Configuration of control unit JI [In Fig. 1, U is a control unit, which can be broadly divided into the above-mentioned brake control unit UB, throttle control unit/
) Control unit US for UT and slip control
It is composed of. Control unit U
B performs opening/closing control of each valve 5VI-5V4 as described above based on a command signal from the control unit US. In addition, the control unit U for the J throttle operates the throttle actuator 1 based on the command signal from the control unit US.
Perform drive control in step 4.
The control unit for Nislip control) USJf is composed of a digital computer, more specifically a microcomputer. This (control unit US
, each sensor (or switch) 61 to 68
The signal from is input. The sensor 61 detects the opening degree I of the throttle valve 13. Sensor 62 is clutch 7C.

This is to detect whether or not they are properly fastened.

The sensor 63 detects the gear position of Ja8. 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 racing speed. The sensor 67 detects the amount of operation of the accelerator 69, that is, the opening degree of the accelerator. The sensor 68 detects the amount of operation of the steering wheel 70, that is, the steering angle. The sensors 64, 65, 66 are configured using, for example, a pick bag, and the sensors 61, 63, 67, 68 are configured using, for example, a potentiometer.
2 is constituted by, for example, a switch that operates ON and OFF.

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

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

WD: Number of revolutions of the driving wheels (2, 3) WL: Number of revolutions of the driven wheels (4) (vehicle speed) The throttle control unit U-cho operates the throttle valve 13 (throttle actuator 14) to achieve the target throttle opening. It is controlled by feedback. During this throttle control, when slip control is not performed, control is performed so that the target throttle opening corresponds to the operation amount of the accelerator 69 operated by the driver 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
Without following the characteristics shown in FIG. 2, the throttle control is performed so that the target throttle opening degree Tn calculated by the control technique US is reached.

Control unit) Throttle valve 1 using UT
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 PI-PDiTi 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 -3ET -F P (WDn -WDn-1) -F D (
WDn-2X WDn-1+ WDn-2)...@(
2) WL: Number of revolutions of driven wheels (4) WD: Number of revolutions of driving wheels (2, 3) KP: Proportional constant KI: Fine constant FP: Proportional constant FD: Differential constant SET Two target slip rates (for throttle control) ) The above formula (2
), the throttle opening degree Tn is feedback-controlled to the rotational speed of the drive wheels so that it reaches a predetermined target slip rate SET. In other words, as is clear from the above equation (1), the throttle opening degree is controlled so that the target driving wheel rotation speed WET is expressed by the following equation (3).

PI-FD using the control unit UT described 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 rnJ, 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/l
' The rotation (slip) of the left and right drive wheels 2.3 using UB is feedback-controlled so that the left and right wheels independently reach a predetermined target slip rate SET. In other words, brake control is performed through feedback control so that the driving wheel rotation speed WBT is set by the following equation (4).

In this embodiment, the target slip rate SBT of the brake is set larger than the target slip rate SET of the engine, as will be described later. In other words, the slip control of this embodiment increases or decreases the engine output to a predetermined 5ET (WBT), 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 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).

From Bn, n-1 -F P (WDn -WDn-1,) -F D
(WDr+ -2X WDn-1+ WDn-2)...
(5) KI: v1 coefficient KD: Proportional coefficient FD: Differential coefficient When Bn above is greater than 0 (positive), the brake fluid pressure is increased, and when it is less than 0, it is reduced. This increase/decrease in brake fluid pressure is controlled by the valve 5VI-
This is done by opening and closing 5V4. In addition, the adjustment of the rate of increase/decrease in brake fluid pressure is performed using the above-mentioned valves SVI to SV.
This is done by adjusting (duty control) the ratio of the opening/closing time (duty ratio) of No. 4, and the duty control is proportional to the absolute value of Bn determined by the above equation (5). Therefore, the absolute value of Bn is proportional to the rate of change in brake fluid pressure, and conversely, the duty ratio that determines the rate of increase/decrease also indicates Bn.

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

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

S/C Nislip control area E/G: Slip control by engine B/R Slip control by Nibrake F/B: Feedback control 0/R: Oven loop control R/Y: Recovery control B/A: Backup control A/S: Buffer control S = 0.2 Slip rate at the start of Nislip control (SS) S = 0.17 + target slip rate by brake (S BT
) S = 0.09 Slip rate when stopping slip control by brake (S 5C) S = 0.06: Target slip rate by engine (S ET
) S=0. O1 to 0.02: Slip rate in the range where buffer control is performed S = 0.01 or less Slip rate in the range where backup control is performed The above values are based on data obtained from actually driving on ice burns with spiked tires. This is an indication. Then, S = 0°Ol 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 SBT 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 in FIG. 5, "0.17" is shown as an example. ,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 Figure 13). The reason why the slip rate at the start of control is set to a large value of 0.2 is so that the actual slip rate when this maximum grip force is obtained can be determined, and the slip rate when this maximum grip force is generated is The target slip rates SET and SET for the engine and brake are corrected accordingly. 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.

■to-kl 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 wheels is small, acceleration is not performed without slip control. Of course, in this case,
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.

■t2~1+ (Recovery control) The throttle valve 13 is held at a predetermined opening degree for a predetermined time (for example, 170 m5ec) after the slip converges (S<0.2) (oven loop control). At this time,
The maximum acceleration G WAX at the time S=O/2 (t2) is determined, and the maximum p of the road surface (maximum grip force of the driving wheels) is estimated from this G MAX. Then, the throttle valve 13 is adjusted so as to generate the maximum grip force of the driving wheels.
is held for a predetermined time as described above. 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 slip convergence is predicted (S=0.2 or lower),
As described above, by securing a predetermined torque in advance, acceleration performance is improved.

The optimal throttle opening TVo to achieve the torque applied to the drive wheels that can generate the maximum grip force mentioned above is:
Although it can be determined theoretically from the torque curve and gear ratio of the engine 6, in the embodiment, it is determined based on a map as shown in FIG. 15, for example. This map is created by an experimental method, and when GMAX is 0.15 or less and 0.4 or more, it is set to a predetermined constant value taking into account the measurement error of GMAX. It should be noted that the map shown in FIG. 12 is based on the assumption that the vehicle is at a certain gear position (for example, 1st gear), and the optimum throttle opening Tvo is corrected at other gear positions.

■ t4 to t7 (backup control, buffer control) In order to cope with the abnormal decrease in the slip rate S, backup control is performed (open loop control), that is, when S<0,01, The feedback control is stopped and the throttle valve 13 is opened in one step. When the slip rate is between 0.01 and 0.02, 1m control is performed to smoothly transition to the next feedback control (1+ to t5 and v:t
6-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 feedback control @ calculation and the throttle opening degree T1 obtained by backup control calculation are set to The throttle opening degree To is obtained by proportionally distributing the amount by o.

■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 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.

In this embodiment, the slip control by the brake is used for emergency purposes to bring down extremely excessive slip as quickly as possible, and after the slip reaches a relatively small value, only the slip control by the engine is performed. It is. The slip control target [(slip rate in the embodiment) during acceleration is set by changing only the engine control target value SET.

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. 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. When 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. If this P5 determines NO,
At P6, it is determined whether 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 (0.06 in the embodiment) of the target slip rate SET for the engine (throttle) is set. Thereafter, in P9.2, when there is a request for acceleration as described later, the SET is corrected. Also, in PIO, the target slip rate SO for brakes is
The initial value of T (0.17 in the example) is set. After this, brake control using pH and engine control using PI3 are performed for slip control, as will be described later. The initial value at P9 and PIO is the maximum acceleration G WAX measured during the previous slip control.
It is set from the same viewpoint as P7O, which will be described later.

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
3 the slip flag is reset 0 then PI
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 P26. This P2
5. After P26, control is performed in P27 to achieve the target throttle opening (P68, which will be described later).
, 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 connected. When it is determined as YES in this P31, it is assumed that the time is not in the middle of star 2, and P32
The stack flag is reset in . Then, P
33, the current vehicle speed is low, for example 6.3k
It is determined whether or not it is smaller than m/h.

When the determination in P33 is No, a correction value α for slip determination is calculated in P34 according to the steering angle of the steering wheel (see FIG. 14). After this, at P35, the slip rate of the left front wheel 2 as the left driving wheel is set to a predetermined reference value of 0.
It is determined whether or not the value is larger than the value (0, 2+α) obtained by adding α in P34 to P34. With this P35 determination, Y
In the case of ES, it is assumed that the left front wheel 2 is in a slip state, and the slip flag is set. On the other hand, No on P35
When it is determined that this is the case, the slip flag for the left front wheel 3 is reset. Note that the correction value α is set in consideration of the rotational difference between the inner and outer wheels (especially the rotational difference between the driving wheel and the driven wheel) during turning.

After PO2 or P37, P38. P39, P2O
In , the slip flag for the right front wheel 3 is set or reset in the same manner as in P35, PO2, 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 designed to detect only by the number of revolutions. 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 corresponding to a vehicle speed of 10 km/h81. If this P41 is determined as YES,
At P42, the slip flag for the left front wheel 2 is set. Conversely, if P41 is determined as NO, P43
At this point, the slip flag for the left front wheel 2 is reset.

After P42 and 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 (while the vehicle is stuck, the driver tries to escape from the mud etc. while using the half clutch).

In this case, the process moves to P51, and it is determined whether the average value of the rotational speed of the left and right front wheels 2 and 3 as driving wheels is small (for example, whether it is 2 km/h or less in terms of vehicle speed). ), if it is determined NO in P51, P
At 52, it is determined whether stack control is currently in progress. When the determination is No in P52, it is determined in P53 whether the rotation speed of the right front wheel 3 is greater than the rotation speed of the left front wheel 2. If YES is determined in P53, the rotation speed of the right front wheel 3 is 1.5 of the rotation speed of the left front wheel 2.
It is determined whether or not it is greater than double.

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

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

After P56, the vehicle speed is 6.3 km at Pb0.
It is determined whether the value is larger than /h. When this Pb0 is YES, the target rotation speed of the front wheels 2.3 is set to be 1.25 times the rotation speed of the driven wheels indicating the vehicle speed (corresponding to a fullness rate of 0.2). Mata, No with Pb0
In this case, the target rotation speed of the front wheels 2.3 is uniformly set to 10 km/h in P59. Yes at 51
When S, 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 P61, it is determined in P62 whether the slip rate S of the left front wheel 2 is greater than 0.2. N at P62.

In this case, it is determined in P63 whether the slip JS of the right front wheel 3 is greater than 0°2. When the answer is No in P63, it is determined in P64 whether only one of the left and right front wheels 2.3 is under brake control, that is, whether the vehicle is traveling on a split road. If YES in P64, the current slip rate is calculated in P65 according to the drive wheel with the lower slip rate among the left and right front wheels 2.3 (SELECT LOW); conversely, if NO in P64 Of the left and right front wheels 2 and 3, the one with the greater slip rate is also 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.

P65. After P66, it is determined in P67 whether the current slip ratio S is greater than 0.02. When YES in P67, the throttle valve 13 is feedback-controlled for slip control in P68. Of course, at this time, the throttle valve opening (T n ) is P65. Target slip rate SE set in P66 or changed in P76 described later
It is set to realize T.

If NO in P67, it is determined in P2O whether the current fill rate S is greater than 0.01. If YES at this P2O, the buffer control described above is performed at P2O. Also, if P2O is No, P71
In this step, the backup control described above is performed.

On the other hand, if YES in P61, the process moves to PI3, and it is determined whether or not a predetermined slip convergence diameter time (time for performing recovery control, 170 msec as described above in the embodiment) has elapsed. When PI3 is NO, the processing from P73 onward is performed to perform recovery control. That is, first, in P73, the maximum acceleration G WAX of the vehicle l
is measured (time t2 in FIG. 5), and then, in PI4, the optimum throttle opening degree Tv□ is set to obtain this G WAX (see FIG. 15). Furthermore, P
At 75, the PI
The optimum throttle opening degree Two at 4 is corrected. That is, since the torque applied to the drive wheels differs depending on the difference in gear position, PI4 sets the optimum throttle opening Tv0 for a certain reference gear position, and P75 corrects this difference in gear position. be. After this, in P76, the coefficient of friction of the road surface is estimated from G and AX in P73, and the target slip rate SET for slip control by the engine (throttle) and brake is set. Change SBT together. Note that this target completion rate SET. How to change S day T will be explained later. Further, in P77, SET is corrected when there is an acceleration request, as will be described later.

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

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

First, in P81, it is determined whether or not it is currently stacked. If No at P81, at P82,
The maximum value (maximum value) of the brake response speed Bn (corresponding to the duty ratio for opening/closing control of SVI to SV4) is set as a function according to the vehicle speed (the higher the vehicle speed, the larger the value). Conversely, 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 or not the slippage rate S is greater than 0, 09, which is the stopping point of brake control. 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).
), and then, in P86, the above Bn is "0"
It is determined whether or not the value is larger than that. This determination determines whether or not the brake pressure is increasing, assuming that the brake pressure increasing direction is positive and the pressure decreasing direction is negative.

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

If NO in P86, Bn is “negative” or rQ
J, so after converting Bn to an absolute value using P2O, P91
- 93 processes are performed. These P91 to P93 are when depressurizing the right brake 22, and P87, P88, and P8
9 processes are supported.

After P89 and P93, the process moves to P94, and pressure increase or decrease processing is performed for the left brake 21 in the same way as for the right brake 22 (process corresponding to P84 to F93).

On the other hand, when the answer is No in P84, it is time to cancel the brake control, so the brake is released in P95.

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

Change of target slip rate SET, SOT (P76) The target slip rate SET, SET of the engine and brake changed in the above P76 is based on the maximum acceleration G MAX measured in P73, as shown in FIG. 17, for example. It will be changed as follows. As is clear from FIG. 17, in principle, the larger the maximum acceleration GMAX, the larger the target slip rates SET and SET should be. Limit values are set for each of the target slip rates SET and SBT. Furthermore, this P76
In this case, the target slip rate SET for engine control is set in accordance with steady running. That is, the maximum acceleration G WA
Considering the road surface level estimated from X, the target slip rate SET is set to a slip rate that is considerably smaller than the slip rate at which the maximum grip force is obtained.

SET acceleration correction (P9.2, P76) This acceleration correction is performed when the driver requests acceleration.
When the pedal speed of the accelerator 70 is higher than a predetermined value or
When the amount of depression is more than a predetermined value, it is determined as acceleration and
Correct to increase. That is, as shown in FIG. 13, SET is corrected in a direction that generates the maximum grip force compared to when the vehicle is running normally. This correction is
-Although it is possible to bring SET closer to the maximum grip force in general, it is also possible to adjust the degree of approach to this maximum grip force depending on the degree of acceleration required (the greater the degree of acceleration required, the maximum grip strength).

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

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

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

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

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

The above-mentioned characteristics (modes) of (1) to (2) can be selected manually (mode selection), for example, depending on 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.

■To adjust the torque applied to the drive wheels, check the connection state of the clutch 7, and the gear shift 4! ! Of course, the torque applied to the drive wheels may be adjusted by adjusting the gear ratio of 8 (especially good in the case of a continuously variable transmission). Can be adjusted.

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

■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 slippage condition of the drive wheels, it is possible to directly detect the rotation speed of the drive wheels as in the example, but it is also possible to predict the slippage condition according to the condition of the vehicle. In other words, the state of the vehicle may be detected indirectly, for example, an increase in the generated torque or rotational speed of the power source, a change in the accelerator opening, a change in the rotation of the drive shaft, and a change in the steering Condition 8 (cornering), vehicle body lifting state (acceleration), load capacity, etc. can be considered. In addition, by automatically detecting or manually inputting atmospheric temperature, rain, snow, ice, etc., the prediction of the slip state of the drive wheels can be made even more appropriate. You can also do it.

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

(Effects of the Invention) As is clear from the above description, the present invention can obtain sufficient acceleration while ensuring stability during steady running.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram showing one embodiment of the present invention. FIG. 82 is a diagram showing an example of a brake fluid pressure control circuit. FIG. 3 is a block diagram when performing feedback control of the throttle valve. FIG. 4 is a block diagram when feedback controlling the brakes. FIG. 5 is a graph schematically showing a control example of the present invention. 6 to 11 are flowcharts showing control examples of the present invention. 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. fJSl 6 Figure 6 is a graph showing the relationship between slip rate and throttle opening when performing buffer control. FIG. 17 is a graph showing an example of a map used when determining the target slip rate. FIG. 18 is an overall configuration diagram of the present invention. 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: Master 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 rotating shell) 6th: Sensor ( Driven wheel rotation speed) 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. 7 Fig. 8 Fig. 12 Hand ! V Kenshi H Fig. 13 S (, lT' Marikoto -) Fig. 15 MAX Fig. 16 1 "Page 1 Noshi instep (S) Fig. 17 MAX

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; an acceleration detection means for detecting an acceleration request from the driver; and controlling the torque adjustment means so that the slip of the drive wheels reaches a predetermined target value. The vehicle is characterized by comprising: a slip control means; and a target value changing means for changing the target value in a direction in which the maximum grip force of the drive wheels is obtained when an acceleration request is made, compared to when the vehicle is running normally. Slip control device for automobiles.