JP2603226B2 - Automotive slip control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention controls an output torque to a driving wheel of a power plant system to prevent the driving wheel from slipping on a road surface excessively. The present invention relates to a slip control device for an automobile.

(Prior Art) Preventing excessive slip of a drive wheel with respect to a road surface is effective in effectively obtaining a propulsive force of an automobile and in terms of safety such as preventing spin. Then, in order to prevent the slip of the drive wheel from becoming excessive, the rotational torque of the drive wheel may be appropriately controlled.

Conventionally, such a type of slip control is disclosed in JP-A-58-16948 or JP-A-60-56662. Both of the techniques disclosed in these publications are designed to control the rotational torque of the drive wheels by using the braking force applied to the drive wheels by a brake and reducing the torque generated by the engine. . More specifically, 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, while when the slip of the drive wheel is large, In addition to braking, the torque generated by the engine is reduced. Further, in Japanese Unexamined Patent Application Publication No. 60-56662, when only one of the left and right driving wheels has a large slip, braking is performed on only one of the driving wheels having a large slip, while the left and right both wheels are braked. When both the slips of the driving wheels are large, braking is performed on the driving wheels on both sides, and the generated torque of the engine is reduced.

(Problems to be Solved by the Invention) By the way, when the slip control is considered separately from the braking by the driving wheels and from the output torque to the driving wheels, each has advantages and disadvantages.

First, when the driving wheels are braked, the responsiveness is excellent, but on the other hand, a shock is apt to occur and the driving feeling tends to be unfavorable. Moreover, as a result of the brake being heavily used for slip control, there is a problem in reliability of the brake. On the other hand, when the output torque of the power plant system is used, the slip control can be performed smoothly, and not only the control for reducing the rotational torque of the drive wheels but also the control for increasing the rotational torque can be performed freely, but the responsiveness is low. There is a disadvantage that it is bad. In particular, in the case of adjusting the output torque by controlling the engine output, a method of adjusting the engine output by controlling a throttle valve provided in the engine intake passage is generally used. It takes time to flow into the tank, and the control is delayed.

Therefore, by controlling the output torque of the power plant system, it is possible to prevent excessive slip of the drive wheels and to quickly converge the large slip of the drive wheels to the target value. It is desirable for improvement and also for avoiding heavy use of brakes.

Accordingly, an object of the present invention is to provide an automobile slip control device that performs convergence of excessive slip of a drive wheel by controlling output torque to a drive wheel of a power plant system with good responsiveness and without lowering acceleration. To provide.

(Means and Actions for Solving the Problems) In order to achieve the above object, according to the present invention, when a large slip of the drive wheels is converging to a target value, the drive wheel is opened before reaching the target value. The output torque to the drive wheels of the power plant system is controlled to increase by loop control, and then the process is shifted to feedback control. That is, as shown in FIG. 19, by controlling the output torque of at least the drive wheels of the power plant system including the engine, the slip control of the vehicle is made to prevent the slip of the drive wheels on the road surface from becoming excessive. In the apparatus, a torque adjusting means for adjusting an output torque of the power plant system, a slip detecting means for detecting a slip value of the drive wheel with respect to a road surface, and an actual slip value of the drive wheel detected by the slip detecting means is set in advance. And feedback control means for performing feedback control on the torque adjusting means so as to achieve the set target slip value.

During the control by the feedback control means, during the slip convergence process in which the actual slip value of the drive wheel is changing in the decreasing direction and when the slip value is a predetermined slip value larger than the target slip value, only during a predetermined period. And recovery control means for controlling the torque adjusting means so that the output torque becomes a predetermined output in a direction in which the output torque increases by open-loop control instead of the control by the feedback control means.

With this configuration, the delay of the power plant system is compensated for by the recovery control, and the process immediately shifts to the feedback control.

(Example) Hereinafter, an example of the present invention will be described with reference to the attached drawings.

1. Overview of Overall Configuration In FIG. 1, an automobile 1 includes four wheels, that is, left and right front wheels 2 and 3 serving as driving wheels and left and right rear wheels 4 and 5 serving as driven wheels. An engine 6, a clutch 7, a transmission 8, and a differential gear 9 as a power plant system are mounted on a front portion of the automobile 1, and the output torque of the engine 6 is provided as drive wheels 7 via left and right drive shafts 10 and 11. The power is transmitted to the left and right front wheels 2 and 3. Thus, the car 1
It is FF type (front engine / front drive).

In the engine 6, load control, that is, control of generated torque is performed by a throttle valve 13 disposed in the intake passage 12. More specifically, the engine 6 is a gasoline engine, and the generated torque is changed by a change in the intake air amount. The intake air amount is adjusted by the throttle valve 13. The throttle valve 13 is electromagnetically opened and closed by a throttle actuator 14. As the throttle actuator 14, for example, a DC motor, a stepping motor, an electromagnetically driven and controlled by being driven by a fluid pressure such as a hydraulic pressure, etc.
It can be constituted by an appropriate one.

Each of the wheels 2 to 5 is provided with a brake 21, 22, 23 or 24, respectively, and each of the brakes 21 to 24 is a disc brake. This disc brake is
As is known, it has a disk 25 that rotates with the wheels and a caliper 26. The caliper 26 holds the brake pad and includes a wheel cylinder, and a braking force is generated by pressing the brake pad against the disc 25 with a force corresponding to the magnitude of the brake fluid pressure supplied to the wheel cylinder. .

The master cylinder 27 as a brake fluid pressure source
It is a tandem type having two discharge ports 27a and 27b.
The brake pipe 28 extending from the discharge port 27a branches into two branch pipes 28a and 28b on the way, and the branch pipe 28a is connected to (the wheel cylinder of) the right front wheel brake 22.
b is connected to the left rear wheel brake 23. A brake pipe 29 extending from the discharge port 27b branches into two branch pipes 29a and 29b on the way, the branch pipe 29a is connected to the left front wheel brake 21, and the branch pipe 28b is connected to the right rear wheel brake 24. It is connected to the. As described above, the brake piping system is a so-called two-system X type. The branch pipes 28a and 29a for the front wheel brakes 21 and 22 serving as drive wheels are provided with electromagnetic hydraulic pressure control valves 30 or 31 as braking force adjusting means.
Is connected. Of course, the brake fluid pressure generated in the master cylinder 27 depends on the amount of depression (the depression force) of the brake pedal 32 by the driver D.

Brake hydraulic pressure control circuit As shown in FIG. 2, the hydraulic pressure control valves 30 and 31
Each has a cylinder 41 and a piston 42 slidably fitted in the cylinder 41. The inside of the cylinder 41 is defined by the piston 42 into a variable volume chamber 43 and a control chamber 44. The variable volume chamber 43 serves as a passage system for the brake fluid pressure from the master 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 can be changed to generate brake fluid pressure for the brake 21 (22), and increase or decrease or maintain the generated brake fluid pressure. Will be able to do it.

The piston 42 is constantly urged by the return spring 45 in a direction in which the volume of the variable volume chamber 43 increases. A check valve 46 is integrated with the piston 42. When the piston 42 is displaced in a direction to reduce the volume of the variable volume chamber 43, the check valve 46 closes the inflow side to the variable volume chamber 43. As a result, the brake fluid pressure generated in the variable volume chamber 43 is reduced by the brake 21 (2
2) It acts only on the side and does not act on the brakes 23, 24 of the rear wheels 4, 5 as driven wheels.

Adjustment of the displacement position of the piston 42 is performed by adjusting the control hydraulic pressure with respect to the control chamber 44. To explain this point in detail, a supply pipe 48 extending from a reservoir 47 is branched into two parts on the way, and one branch pipe 48R is connected to the control chamber 44 of the valve 30.
To the control chamber 4 of the valve 31.
Connected to 4. The supply pipe 48 is connected to a pump 49 and a relief valve 50, and the branch pipe 48L (48R) is connected to a supply valve SV3 (SV2) composed of an electromagnetic on-off valve. Each control room 44 is further connected to a reservoir 47 via a discharge pipe 51R or 51L, and a discharge valve SV4 (SV1) composed of an electromagnetic on-off valve is connected to the discharge pipe 51L (51R).

At the time of braking using the hydraulic pressure control valve 30 (31) (during slip control), the brake by the operation of the brake pedal 32 basically does not work due to the action of the check valve 46. However, the hydraulic pressure control valve 30
When the brake fluid pressure generated in (31) is small (for example, during pressure reduction), the brake by operating the brake pedal 32 operates. Of course, when the brake fluid pressure for slip control is not generated at the pressure reducing control valve 30 (31), the master cylinder 27 and the brake 21 (22) are in communication with each other. Normal braking action will be performed.

The valves SV1 to SV4 are controlled to open and close by a brake control unit UB described later. Brake 2
The following table summarizes the relationship between the state of the brake fluid pressure to the valves 1 and 22 and the operation relationship between the valves SV1 to SV4.

1. Outline of Configuration of Control Unit In FIG. 1, U is a control unit,
This is roughly divided into a brake control unit UB, a throttle control unit UT, and a slip control control unit US. The control unit UB controls the opening and closing of each of the valves SV1 to SV4 based on the command signal from the control unit US as described above. Further, the throttle control unit UT controls the drive of the throttle actuator 14 based on a command signal from the control unit US.

The control unit US for slip control is constituted by a digital computer, more specifically, a microcomputer. Signals from the sensors (or switches) 61 to 68 are input to the control unit US. The sensor 61 is connected to the throttle valve 13
This is for detecting the opening degree. The sensor 62 detects whether the clutch 7 is engaged. Sensor 63
Is for detecting the gear position of the transmission 8. Sensor 64,
Reference numeral 65 indicates the number of rotations of the left and right front wheels 2 and 3 as drive wheels. The sensor 66 detects the rotational speed of the rear left wheel 4 as a driven wheel, that is, the vehicle speed. The sensor 67 detects the operation amount of the accelerator 69, that is, the accelerator opening. The sensor 68 detects the operation amount of the steering wheel 70, that is, the steering angle. The sensors 64, 65, and 66 are each configured using, for example, a pickup, and the sensors 61, 6
3, 67, 68 are configured using, for example, a potentiometer, and the sensor 62 is configured, for example, by a switch that operates ON and OFF.

Note that the control unit US is basically a CPU, RO
Equipped with M, RAM, and CLOCK.In addition to having an input / output interface, A /
It also has a D or D / A converter, but since these points are the same as those in the case of using a microcomputer, detailed description is omitted. The maps and the like in the following description are those stored in the ROM of the control unit US.

Next, the control contents of the control unit U will be sequentially described. The slip ratio, that is, the slip value S used in the following description is defined by the following equation (1).

WD: Number of rotations of drive wheels (2, 3) WL: Number of rotations of driven wheel (4) (vehicle speed) Throttle control The control unit UT feeds back the throttle valve 13 (throttle actuator 14) so that the target throttle opening is achieved. It is controlled.
During the throttle control, when the slip control is not performed, the operation amount of the accelerator 69 operated by the driver D is
FIG. 12 shows an example of a correspondence relationship between the accelerator opening and the throttle opening at this time so that the target throttle opening corresponds to 1: 1. In the slip control, the control unit UT does not follow the characteristics shown in FIG.
The throttle control is performed so that the target throttle opening degree Tn calculated in step (1) is obtained.

Throttle valve 1 using control unit UT
In the embodiment, the feedback control of 3 is performed by PI-PD control in order to compensate for the fluctuation of the response speed of the engine 6. That is, during the slip control of the drive wheels, the opening degree of the throttle valve 13 is controlled by PI-PD so that the current slip rate matches the target slip rate. More specifically, the target throttle opening Tn for slip control
Is calculated by the following equation (2).

WL: Revolution of driven wheel (4) WD: Revolution of drive wheel (2, 3) KP: Proportional constant KI: Integral constant FP: Proportional constant FD: Differential constant SET: Target slip rate (for throttle control) As shown in (2), the throttle opening Tn is feedback-controlled on the rotation speed of the drive wheels so as to reach a predetermined target slip ratio SET. In other words, as is apparent from the above equation (1), the throttle opening is determined by the following equation (3) when the target drive wheel rotational speed WET is Is controlled so that

The PI-PD control using the above-described control unit UT is shown in FIG. 3 as a block diagram, and “S ′” shown in FIG. 3 is an “operator”. The suffixes “n” and “n−1” indicate the value of each signal at the current time and at the time of the previous sampling.

Brake control During slip control, the control unit UB
The rotation (slip) of the left and right drive wheels 2 and 3 using the feedback control is independently controlled so as to reach a predetermined target slip ratio SBT. In other words, in the brake control, feedback control is performed so that the driving wheel rotational speed WBT is set by the following equation (4).

In this embodiment, the target slip rate SBT of the brake is set to be larger than the target slip rate SET of the engine as described later. In other words, in the slip control of the present embodiment, the engine output is increased or decreased so as to attain a predetermined SET (WET), and the torque is increased or decreased by the brake so as to attain a larger SBT (WBT).
The frequency of use of the brake is reduced. In this embodiment, feedback control that satisfies the above equation (4) is performed by I-PD control having excellent stability. More specifically, the brake operation amount (valve 3
The operation amount of the piston 44 at 0 and 31) Bn is given by the following equation (5).
Is calculated by

KI: Integral coefficient KD: Proportional coefficient KD: Derivative coefficient When Bn is greater than 0 ("positive"), the brake fluid pressure is increased, and when it is 0 or less, the pressure is reduced. The increase and decrease of the brake fluid pressure is controlled by the valves SV1 to SV4 as described above.
Is performed by opening and closing. Adjustment of the rate of increase and decrease of the brake fluid pressure is performed by adjusting (duty control) the ratio (duty ratio) of the opening and closing time of the valves SV1 to SV4, and is obtained by the above equation (5).
Duty control is performed in proportion to the absolute value of Bn. Therefore, the absolute value of Bn is proportional to the change speed of the brake fluid pressure, and conversely, the duty ratio that determines the increase / decrease speed is
It also indicates Bn.

FIG. 4 is a block diagram showing the I-PD control by the control unit UB described above.
"S '" shown in the figure is an "operator".

Overall Overview of Slip Control An overall overview of slip control by the control unit U will be described with reference to FIG. In addition,
The meanings of the signs and numerical values shown in FIG. 5 are as follows.

S / C: Slip control area E / G: Slip control by engine B / R: Slip control by brake E / B: Feedback control O / R: Open loop control R / Y: Recovery control B / A: Backup control A / S: Buffering control S = 0.2: Slip rate at the start of slip control (SS) S = 0.17: Target slip rate by brake (SBT) S = 0.09: Slip rate at stop of slip control by brake (SBC) S = 0.06: Target slip ratio by engine (SET) S = 0.01 to 0.02: Slip ratio in the range where buffer control is performed S = 0.01 or less: Slip ratio in the range where backup control is performed Are shown based on the data obtained by traveling. Then, S = 0.01 and 0.02 for performing the buffer control A / S, and the slip ratio S = 0 when the slip control by the brake is stopped.
09 is unchanged in each embodiment. On the other hand, the target slip rate SBT due to the brake, the target slip rate SET due to the engine, and the slip rate SS at the start of the slip control are changed by road surface conditions and the like, and as an example in FIG. , “0.06” or “0.2”. The slip ratio S = 0.2 at the start of the slip control uses the slip ratio at the time of generation of the maximum grip force obtained when the spike tire is used (see the solid line in FIG. 13). In this way, the slip ratio at the start of the slip control is increased to 0.2 in order to obtain the actual slip ratio when the maximum grip force is obtained. The target slip rates SET and SBT due to the engine and the brake are corrected in accordance with the slip rate. The solid line in FIG. 13 shows how the magnitude of a grip force and a lateral force (shown as a coefficient of friction with respect to a road surface) at the time of a spike tire changes in relation to a slip ratio. The broken line in FIG. 13 shows the relationship between the grip force and the lateral force in the case of a normal tire.

Based on the above, FIG. 5 will be described with the passage of time.

Since t ₀ ~t ₁ slip ratio S does not exceed the S = 0.2 as the slip control starting condition, the slip control is not performed. That is, when the slip of the driving wheel is small, the acceleration performance can be improved by not performing the slip control.
(Driving with great gripping power). Of course, in this case, the characteristic of the throttle opening with respect to the accelerator opening is
It is determined uniformly as shown in Fig. 12.

t ₁ with ~t ₂ slip control is started, the slip rate is when the above slip control stop point by the brake (S = 0.09). At this time, since the slip ratio is relatively large, slip control is performed by reducing the torque generated by the engine and braking by the brake. In addition, since the target slip ratio of the brake (S = 0.17) is larger than the target slip ratio of the engine (S = 0.06), the brake is pressurized during a large slip (S> 0.17), but when the slip is small. In (S <0.17), the brake is not pressurized, and the control is performed only by the engine so that the slip is converged.

t _{2 to} t ₄ (Recovery control) In this embodiment, it is determined that the slip is converging by the slip rate S, and for a predetermined time (for example, 170 msec) after the slip rate becomes S <0.2. The recovery control for maintaining the throttle valve 13 at a predetermined opening degree by the open loop control is performed. Then, the maximum acceleration GMAX at the time point of S = 0/2 (t2) is obtained, and the maximum μ of the road surface (the maximum grip force of the driving wheel) is estimated from the GMAX, and the maximum grip force of the driving wheel is generated. Thus, the opening of the throttle valve 13 (optimum throttle opening TVo) is set.

Such recovery control prevents a drop (overshoot) of the vehicle body acceleration G immediately after the convergence of the slip, and secures a predetermined torque in advance before the convergence of the slip, thereby improving the acceleration performance. .

The optimal throttle opening TVo for realizing the output torque to the drive wheels that can generate the maximum grip force is:
Although it is theoretically obtained from the torque curve and the gear ratio of the engine 6, in the embodiment, it is determined based on, for example, a map as shown in FIG. 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 in consideration of the measurement error of GMAX. Note that the map shown in FIG. 12 is based on a certain gear (for example, first speed), and corrects the optimum throttle opening TVo at another gear.

t _{4 to} t ₇ (backup control, buffer control) The control shown here is performed to cope with an abnormal decrease in the slip ratio S, and usually shifts from the recovery control to the feedback control.

That is, backup control (open loop control)
When S <0.01, the feedback control is stopped and the throttle valve 13 is gradually opened. When the slip ratio is between 0.01 and 0.02, buffer control is performed to smoothly shift to the next feedback control. (T ₄ ~t ₅ and t ₆ ~t _7). This backup control is performed when the feedback control and the recovery control cannot cope. Of course, the backup control has a sufficiently high response speed than the feedback control.

In this embodiment, the rate of increase of the throttle opening in the backup control is 0.5% with respect to the previous throttle opening every 14 msec of the throttle opening sampling time.
It is assumed to be added by the opening.

Further, in the above buffer control, as shown in FIG. 16, a throttle opening T ₂ obtained by the feedback control calculation, and a throttle opening T ₁ obtained by the backup control operation, the proportional by the current slip ratio So The throttle opening To is obtained by distribution.

By controlling the up t ₇ even when t ₇ ~t ₈ slip rate is abnormally low, a smooth transition to the engine only by the slip control (feedback control).

After t ₈ Since the accelerator 69 is completely closed by the driver D, the slip control is stopped. At this time, even if the opening degree of the throttle valve 13 is left to the will of the driver D, there is no danger of re-slip because the torque is sufficiently reduced. In the embodiment, in addition to the full closing of the accelerator, the target throttle opening by the slip control is determined from the throttle opening determined by FIG. 12 corresponding to the accelerator opening operated by the driver. Is also performed when it becomes smaller.

Details of Slip Control (Flowchart) Next, the details of the slip control will be described with reference to the flowcharts of FIGS. 6 to 11. In the embodiment, in the stack in which the vehicle 1 is stuck in muddy or the like, A stack control for getting out of the mud or the like is also performed by using the brake control. In the following description, P indicates slip.

FIG. 6 (Main) After the system has been initialized in P1, it is determined in P2 whether or not the vehicle is currently in a stack state (a state in which it cannot be stuck in a muddy area or the like). This determination is made by checking whether or not a stack flag described later is set. If the determination in P2 is NO, it is determined in P3 whether the accelerator 69 is fully closed. If NO is determined in P3, it is determined in P4 whether the current throttle opening is larger than the accelerator opening. If NO is determined in P4, it is determined in P5 whether the slip control is currently being performed. This determination is made by checking whether the slip control flag is set. this
If NO is determined in P5, it is determined in P6 whether or not a slip has occurred to perform slip control. This determination is made by checking whether a slip flag has been set for the left and right front wheels 2 and 3 described below. When NO is determined in P6, the process proceeds to P7, and the slip control is stopped (normal traveling).

When YES is determined in P6, the flow shifts to P8, where a slip control flag is set. Subsequently, in P9, the initial value of the target slip ratio SET for the engine (throttle) (0.06 in the embodiment) is set, and in P10, the initial value of the target slip ratio SBT for the brake (in the embodiment,
0.17) is set. Thereafter, as described later, brake control at P11 and engine control at P12 are performed for slip control. The setting of the initial values in P9 and P10 is based on the maximum acceleration GMAX obtained in the previous slip control from the same viewpoint as in P76 described later.

When YES is determined by the slip control flag in P5, the flow shifts to P11 described above, and the slip control is continuously performed.

When YES is determined in P4, it means that the slip control has become unnecessary, and the routine shifts to P14. In this P14, the slip control flag is reset. Next, the engine control is stopped at P15, and the brake control is performed at P16. The brake control in P16 is performed as a countermeasure during stacking.

When YES is determined in P3, the brake is released in P13, and then the processing after P14 is performed.

When YES is determined in P2, the processing after P15 is performed.

7 and 8 The flowchart of FIG. 7 is interrupted, for example, every 14 msec with respect to the main flowchart of FIG.

First, in P21, each signal from each of the sensors 61 to 68 is input for data processing. Next, after the process of slip detection described later is performed in P22, the throttle control is performed in P23.

The throttle control at P23 is performed according to the flowchart shown in FIG. First, in P24, it is determined whether the slip control flag is set, that is, whether the slip control is currently being performed. this
When YES in P24, control for controlling the throttle valve 13 is selected for slip control, that is, control that realizes a predetermined target slip ratio SET without following the characteristics shown in FIG. When NO is determined in P24, the control of opening and closing the throttle valve 13 is performed in P26.
It is selected according to the will of the driver D (according to the characteristics shown in FIG. 12). After P25 and P26, control for realizing the target throttle opening is performed at P27 (control according to P68, P70 and P71 described later or twelfth control).
Control according to the characteristics in the figure).

FIG. 9 (Slip and Slip Convergence Detection Processing) The flowchart in FIG. 9 corresponds to P22 in FIG. This flowchart is for detecting whether or not a slip which is a target of the slip control has occurred, whether or not a large slip is converging, and whether or not the vehicle is stuck.

First, at P31, it is determined whether or not the clutch 7 is completely connected. If YES is determined in this P31,
The stack flag is reset in P32 as if it was not in the stack. Next, in P33, it is determined whether or not the current vehicle speed is low, that is, for example, smaller than 6.3 km / h.

When NO is determined in P33, a correction value α for slip determination is calculated in P34 according to the steering angle (see FIG. 14). Thereafter, in P35, it is determined whether or not the slip ratio of the left front wheel 2 as the left driving wheel is larger than a value (0.2 + α) obtained by adding α in P34 to the predetermined reference value 0.2. If the determination in P35 is YES, it is determined that the left front wheel 2 is in the slip state, and the slip flag is set. Conversely, if NO is determined in P35, it is determined that the slip state of the left front wheel 2 is converging, and the slip flag is reset. The correction value α is set in consideration of a rotation difference between the inner and outer wheels during turning (particularly, a rotation difference between a driving wheel and a driven wheel).

After P36 or P37, setting or resetting of the slip flag for the right front wheel 3 as the right driving wheel is performed in P38, P39, and P40 in the same manner as in P35, P36, and P37.

When YES is determined in P33, the vehicle is at low speed, and the vehicle speed is used, that is, the error in the calculation of the slip rate based on the equation (1) becomes large.
The detection is made based only on the rotation speed of the drive wheels.
That is, in P41, the rotation speed of the left front wheel 2 is increased to the vehicle speed of 10 k
It is determined whether or not the rotation speed is higher than m / h. If YES is determined in P41, the left front wheel 2
Is set. Conversely, if NO is determined in P41, the slip flag of the left front wheel 2 is reset in P43.

After P42 and P43, in P44, P45 and P46, the right front wheel 3
Is set or reset in the same manner as in the above P41 to P43. these
The reset of the slip flag in P36, P40, P43, and P36 is used to determine the shift to slip convergence in P61 (FIG. 10) described later.

In P31, when it is determined as NO, it is considered that there is a possibility that the vehicle is in the stuck state. In this case, shift to P51,
It is determined whether or not the average value of the rotational speeds of the left and right front wheels 2 and 3 as drive wheels is small (for example, 2 km / h in terms of vehicle speed).
It is determined whether or not: If NO is determined in P51, it is determined in P52 whether or not the stack control is currently being performed. If NO is determined in P52, it is determined in P53 whether the rotation speed of the right front wheel 3 is higher than the rotation speed of the left front wheel 2. When YES is determined in P53, it is determined whether or not the rotation speed of the right front wheel 3 is larger than 1.5 times the rotation speed of the left front wheel 2. When YES is determined in this P54, the stack flag is set in P56. On the other hand, when NO is determined in P54, it is determined that the vehicle is not in the stack, and the above-described processing from P32 is performed.

If NO in P53, it is determined in P55 whether the rotation speed of the left front wheel 2 is larger than 1.5 times the rotation speed of the right front wheel 3 or not. If YES in P55, the process proceeds to P56, and if NO, the process proceeds to P32.

After P56, it is determined in P57 whether the vehicle speed is higher than 6.3 km / h. If YES in this P57,
The target rotation speed of the front wheels 2 and 3 is set to 1.
It is set to be 25 times (equivalent to a slip rate of 0.2). When NO in P57, in P59, the front wheel 2,
The target speed of 3 is set uniformly to 10 km / h.

FIG. 10 (brake control) The flowchart shown in FIG. 10 corresponds to P11 and P16 in FIG.

First, in P81, it is determined whether or not the stack is currently being stacked. When NO in P81, in P82, the limit value (maximum value) of the brake response speed Bn (corresponding to the duty ratio for opening / closing control of SV1 to SV4) is set to a function corresponding to the vehicle speed (the larger the vehicle speed, the larger the value) Set as Conversely, P81
If the answer is YES in P83, the limit value BLM is
Set as a constant value smaller than 82. Note that the processing in P82 and P83 takes into account that, when Bn is calculated as in the above equation (5), the rate of increase and decrease of the brake fluid pressure is too fast, which may cause vibration or the like. Done. In addition, in P83, since it is not particularly preferable that the braking force applied to the drive wheels suddenly changes due to escape from the stack, the limit value is set to a small constant value.

After P82 or P83, the slip rate S at P84
Is greater than 0.09, which is the stop point of the brake control. If YES in P84, the operation speed Bn of the right front wheel brake 22 is calculated in P85 (corresponding to Bn in the I-PD control in FIG. 4). Thereafter, in P86, it is determined whether or not Bn is greater than “0”. This determination is a determination as to whether the brake pressure is in the pressure increasing direction when the pressure increasing direction is considered to be positive and the pressure decreasing direction is considered negative.
If YES in P86, it is determined in P87 whether Bn> BLM. If YES in P87, set Bn to the limit value BLM
, The pressure of the right brake 22 is increased in P89. When NO in P87, the pressure is increased in P89 with the value of Bn set in P85.

When NO in P86, Bn is “negative” or “0”, so after Pn is converted to an absolute value in P90, the processes in P91 to 93 are performed. Steps P91 to P93 are for depressurizing the right brake 22, and correspond to the processing of P87, P88 and P89.

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

On the other hand, if NO in P84, it means that the brake control is to be stopped, so the brake is released in P95.

When the difference between the actual rotation speed of the drive wheel and the target rotation speed (the actual slip ratio and the target slip ratio) is large between P85 and P86, for example, the integration constant KI in the above equation (5) is calculated. Performing the correction to reduce the value is preferable in preventing acceleration deterioration and engine stall due to excessive braking.

FIG. 11 (engine control) The flowchart shown in FIG. 11 corresponds to P12 in FIG.

In P61, as described above, the slip by reset the slip flag (whether when passing through the t ₂ time points of FIG. 5) migrated whether the convergence conditions is determined. If NO in P61, it is determined in P62 whether the slip ratio S of the left front wheel 2 is greater than 0.2. If NO in P62, it is determined in P63 whether the slip ratio S of the right front wheel 3 is larger than 0.2. If NO in P63, it is determined in P64 that only one of the left and right front wheels 2, 3 is under brake control,
That is, it is determined whether or not the vehicle is traveling on the splip road. If YES in P64, in P65, the current slip ratio is calculated based on the drive wheel having the lower slip ratio among the left and right front wheels 2 and 3 (select low). Conversely, when the answer is NO in P64, the current slip ratio is calculated according to the drive wheel having the larger slip ratio among the left and right front wheels 2 and 3 (select high). It should be noted that also when the answer is NO in P62 and P63, the process shifts to P66.

The select high in P65 allows the use of the brake to be further avoided by calculating the current slip ratio in order to suppress the slip of the drive wheel that is more likely to slip. Conversely, the select low in the above P65 is used to control the slip of the drive wheel which is more likely to slip by the brake, for example, when traveling on a split road where the friction coefficient of the road surface where the left and right drive wheels are in contact with the ground is different. This makes it possible to run with the grip of the driving wheel on the difficult side.
In the case of this select row, in order to avoid overuse of the brake, it is preferable to limit the time to, for example, a predetermined time, or to provide a backup means for stopping the select row when the brake is overheated.

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

If NO in P67, the current slip ratio S is
It is determined whether it is greater than 0.01. If the answer is YES in P69, the buffer control described above is performed in P70. If NO in P69, the above-described backup control is performed in P71.

On the other hand, if YES in P61, it is determined that the large slip of the drive wheels is converging, and the flow shifts to P72 to perform the recovery control. That is, first, a predetermined time after the shift to the slip convergence direction in P72 (time for performing the recovery control, 170 msec in the embodiment as described above)
It is determined whether or not it has elapsed. When the answer is NO in P72, the processing after P73 is performed to perform the recovery control. That is, first, at P73, the maximum acceleration GMAX is measured of the automobile 1 (FIG. 5 t ₂ time). Next, in P74, the optimum throttle opening Tvo is set so as to obtain this GMAX (see FIG. 15). Further, in P75, the transmission 8
The optimal throttle opening T at P74 according to the current gear position of
vo is corrected. That is, since the applied torque to the drive wheels also varies depending on the shift speed, P74 sets the optimum throttle opening Tvo for a certain reference shift speed,
At 75, this difference in the gear position is corrected. Thereafter, in P76, the friction coefficient of the road surface is estimated from GMAX in P73, and both the target slip rates SET and SBT of the subsequent slip control by the engine (throttle) and the brake are changed. How to change the target slip rates SET and SBT will be described later.

If YES in P72, it means that the recovery control is to be ended, and the above-described processing from P62 is performed.

Change of target slip rates SET and SBT (P76) The target slip rates SET and SBT of the engine and the brake changed in P76 are based on the maximum acceleration GMAX measured in P73, for example, as shown in FIG. Be changed. As is apparent from FIG. 17, in principle, as the maximum acceleration GMAX increases, the target slip rates SET and SBT increase.
Is to be increased. And the target slip rate S
ET and SBT are each provided with a limit value.

As described above, according to the present embodiment, as shown in FIG. 18, when the drive wheels are converging to a target value from a large slip, the throttle opening is previously adjusted by open loop control from feedback control. The control is switched to recovery control that opens a predetermined amount, and thereafter feedback control is performed again.

Therefore, the occurrence of the overshoot phenomenon shown by the one-dot chain line in FIG. 18 is prevented, and the control smoothly proceeds to the feedback control and converges to the target value. As a result, a drop in acceleration is prevented.

The target throttle opening in the recovery control is the optimum throttle opening TV that generates the maximum grip force of the drive wheels.
Since it is set to o, improvement in acceleration and prevention of re-slip are achieved.

Further, since the target value is set in the feedback control performed after the recovery control in consideration of the maximum clipping force of the driving wheels, the recovery control is smoothly shifted to the feedback control, and the feedback control is performed. Acceleration in the control region can be improved. Feedback control is stable against disturbance.
Since the P1-PD control is used, the convergence of a large spin, which is inconsistent with the recovery control, is excellent in both responsiveness and stability.

Although the embodiment has been described above, the present invention is not limited to this and includes, for example, the following case.

In the case of adjusting the generated torque of the engine as adjustment of the output torque to the drive wheels of the power plant system,
It is preferable to change and control the factor that most affects the output generated by the engine. That is, it is preferable that the generated torque is adjusted by so-called load control. In the case of an Otto type engine (for example, a gasoline engine), the amount of air-fuel mixture is adjusted. In the case of a diesel engine, the amount of fuel injection is adjusted. Is preferred. However, the present invention is not limited to this load control, and may be performed by adjusting the ignition timing in an Otto engine, or by adjusting the fuel injection timing in a diesel engine. Further, in the case of a supercharging engine, the supercharging may be performed by adjusting the supercharging pressure. Of course,
The power source is not limited to the internal combustion engine, but may be an electric motor. In this case, the generated torque may be adjusted by adjusting the power supplied to the motor. The adjustment may be performed by adjusting not only the engine but also the connection state of the clutch 7 and the gear ratio of the transmission 8. In this case, a continuously variable transmission (CVT) is particularly preferable.

The vehicle 1 is not limited to the front wheels 2 and 3 having drive wheels, and the rear wheels 4 and 5 may be drive wheels or all four wheels may be drive wheels.

In order to detect the slip state of the drive wheel, the slip state may be directly detected like the rotation speed of the drive wheel as in the embodiment, but in addition, the slip state is predicted according to the state of the vehicle, that is, You may make it detect indirectly. Such vehicle states include, for example, an increase in the generated torque or the number of revolutions of the power source, a change in the accelerator opening, a change in the rotation of the drive shaft, a steering state (cornering), and a floating state of the vehicle body (acceleration). , Load capacity, and the like. In addition to this, the road surface μ such as atmospheric temperature, rain, snow, ice burn, etc.
Can be automatically detected or input manually to make the prediction of the slip state of the drive wheels even more appropriate.

(Effects of the Invention) As is apparent from the above description, the present invention is expected to increase the output torque from the power plant system to the drive wheels in advance when the drive wheels are converging from the large slip to the target value. Since the control is shifted to the feedback control after adding the control, the output torque is prevented from being excessively reduced, and the acceleration performance is prevented from deteriorating.
After the convergence of the slip, it is difficult for the slip to re-occur.

As a result, the responsiveness and stability of the control system can be achieved at the same time, and the propulsion of the vehicle can be improved and re-slip can be prevented.

[Brief description of the drawings]

FIG. 1 is an overall system diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing an example of a control circuit for a brake fluid pressure. FIG. 3 is a block diagram when the feedback control of the throttle valve is performed. FIG. 4 is a block diagram when the brake is feedback controlled. 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 characteristics of the throttle opening with respect to the accelerator opening when the slip control is not performed. FIG. 13 is a graph showing the relationship between the grip force of the drive wheels and the lateral force by the relationship between the slip ratio and the coefficient of friction on the road surface. FIG. 14 is a graph showing a correction value when the slip ratio at the start of the slip control is corrected according to the steering angle. FIG. 15 is a graph showing the optimal throttle opening corresponding to the maximum acceleration during the recovery control. FIG. 16 is a graph showing the relationship between the slip ratio and the throttle opening when performing the buffer control. FIG. 17 is a graph showing an example of a map used for determining a target slip ratio. FIG. 18 is a graph showing the operation and effect of the embodiment. FIG. 19 is an overall configuration diagram of the present invention. 1: Automobile 2, 3: Front wheel (drive wheel) 4, 5: Rear wheel (driven wheel) 6: Engine 7: Clutch 8: Transmission 13: Throttle valve 14: Throttle actuator 61: Sensor (throttle opening) 62: Sensor (clutch) 63: Sensor (gear stage) 64, 65: Sensor (drive wheel speed) 66: Sensor (driven wheel speed) 67: Sensor (accelerator opening) 68: Sensor (steering wheel steering angle) 69: Accelerator U: Control unit

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiro Matsuoka 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Corporation (56) References JP-A-61-129432 (JP, A)

Claims (1)

(57) [Claims] (1) By controlling an output torque to a driving wheel of a power plant system including at least an engine,
In a vehicle slip control device configured to prevent an excessive slip of a drive wheel on a road surface, a torque adjusting means for adjusting an output torque of the power plant system, a slip detecting a slip value of a drive wheel on a road surface Detecting means; feedback control means for performing feedback control on the torque adjusting means so that the actual slip value of the drive wheel detected by the slip detecting means becomes a preset target slip value; During the control, when the actual slip value of the drive wheel is a predetermined slip value larger than the target slip value during a slip convergence process in which the actual slip value of the drive wheel is changing in a decreasing direction, the feedback control means is provided only during a predetermined period. Output loop by open-loop control instead of And a recovery control means for controlling the torque adjusting means so as to obtain a predetermined output in a direction in which the torque increases. A slip control device for an automobile, comprising: