JP2873490B2 - Vehicle traction control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention prevents a drive wheel from slipping due to an excessive drive torque, so that the slip value of the drive wheel becomes a target slip value. The present invention relates to a traction control device for a vehicle that controls a driving torque of a vehicle.

(Prior art) If the driving wheel slips excessively against the road surface due to excessive driving torque, the vehicle cannot obtain sufficient propulsive force and the acceleration performance decreases, or the cornering force decreases and the vehicle spins. Occurs.

Therefore, conventionally, in order to prevent the slip of the drive wheel from becoming excessive due to the excessive drive torque, the slip value of the drive wheel is calculated, and the drive wheel is set so that the slip value becomes a predetermined target slip value set separately. Traction control of a vehicle that controls the driving torque of a vehicle is known.

In general, the grip force and the cornering force of the tire on the road surface in the front-rear direction change with respect to the slip value as shown in FIG. Therefore, conventionally, it is determined whether the vehicle is running straight or turning based on the steering angle of the steering wheel, and the target slip value is set to the value A in FIG. During traveling, the target slip value is reduced and set to the value B in the figure. By doing so, the driving force in the front-rear direction is reduced, but the cornering force is increased, and the traveling stability during turning traveling is prevented to prevent spin etc. It is also known to do so.

Japanese Patent Application Laid-Open No. 64-30869 discloses a method of reducing the target value (target slip value) of slip control by applying a braking force at the start of a steering angle based on the above concept.

(Problems to be Solved by the Invention) In the traction control as described above, the target slip value decreases when the vehicle starts turning, and increases when the vehicle returns to straight running.

However, for example, during a counter-steering run or a slalom run in a steady circuit, the steering wheel is continuously operated left and right. At this time, the steering wheel temporarily goes straight while the steering wheel is continuously operated left and right. Therefore, if the target slip value is simply reduced during turning and the target slip value is increased during straight running, the steering wheel is continuously operated left and right during countersteer running or slalom running as described above. The target slip value increases assuming that the vehicle is in a straight running state temporarily during the operation.

However, during counter-steering or slalom running as described above, the cornering force is basically increased to increase the lateral grip force of the drive wheels on the road surface, thereby preventing the vehicle from spinning and stabilizing turning performance. Therefore, it is not desirable for the target slip value to increase even during the left-right continuous operation of the steering wheel even temporarily, as described above.

In view of the above circumstances, an object of the present invention is to provide a traction control device for a vehicle which prevents a target slip ratio from temporarily increasing during traveling such as counter steer traveling or slalom traveling and impairing traveling stability. It is in.

(Means for Solving the Problems) A traction control device for a vehicle according to the present invention achieves the above object by providing a slip value of a drive wheel in order to prevent a slip of a drive wheel from becoming excessive due to an excessive drive torque. A traction control device for a vehicle, comprising: control means for controlling the drive torque of the drive wheels so that the target slip value is obtained and setting the target slip value to be smaller during straight turning than during straight running to control the drive torque. And wherein the control means controls the driving torque for a predetermined time after the turning traveling is completed, using the target slip value as a target slip value during the turning traveling.

The turning traveling or the straight traveling can be determined by, for example, the front wheel steering angle, and the absolute value of the front wheel steering angle is a predetermined value, for example,
If it is 30 degrees or more, it can be turned, and if it is less than 30 degrees, it can be made straight.

The slip value may be any value as long as it is a numerical value indicating the degree of slip of the drive wheel. For example, a value obtained by subtracting the driven wheel speed from the drive wheel speed can be used.

The control of the drive torque may be any control that can control the drive torque applied to the drive wheels.
For example, a brake control for controlling a braking force, a throttle control for controlling an engine output by changing a throttle opening, or the like or a combination thereof can be adopted.

The predetermined time is preferably a time that can sufficiently cover the duration of the temporary straight traveling state that occurs when the steering wheel is continuously operated left and right during the countersteer running or the slalom running, and the like. Is a time that can be sufficiently covered, and is desirably a shorter time.

(Operation) In the traction control device having the above-described configuration, the target slip value is kept at the small target slip value during the turning traveling for a predetermined time after the turning traveling is completed. The slip value is set to a large target slip value during straight running, but if turning again after a predetermined time has elapsed, the target slip value remains at the small target slip value during turning.

Therefore, when the vehicle is running counter-steering or slalom as described above, the vehicle is in a straight traveling state temporarily, but it is a transitional vehicle and the vehicle immediately turns again. By setting
It is possible to prevent an increase in the target slip value during such a temporary straight traveling state, and to avoid a decrease in running stability during turning due to a temporary increase in the target slip value.

(Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

The embodiment described below uses a control unit as a control unit.
By the UTR, slip control (traction control) of the drive wheels is performed by throttle control for reducing the engine generated torque by reducing the throttle opening of the engine and brake control for applying a braking force to the drive wheels.

In FIG. 1, A is an automobile provided with the traction control device according to the present embodiment. In the car A, the left and right front wheels 1FL and 1FR are driven wheels, and the left and right rear wheels 1RL and
RR is a drive wheel. That is, the generated torque of the engine 2 mounted on the front of the vehicle body is transmitted to the left rear wheel 1RL via the left driving wheel 6L after passing through the automatic transmission 3, the propeller shaft 4, and the differential gear 5, and Drive wheel 6R
To the right rear wheel 1RR.

Configuration of Automatic Transmission The automatic transmission 3 includes a torque converter 11 and a multi-stage transmission gear mechanism 12. The shift is performed by changing the combination of the excitation and the demagnetization of the plurality of solenoids 13a incorporated in the hydraulic circuit of the transmission gear mechanism 12. Further, the torque converter 11 has a hydraulically operated lock-up clutch 11A. By switching between excitation and demagnetization of a solenoid 13b incorporated in a hydraulic circuit of the clutch, engagement and engagement of the lock-up clutch 11A are performed. Release is performed.

The solenoids 13a and 13b are controlled by a control unit UAT for an automatic transmission. This control unit UAT
As is known, the shift characteristic and the lock-up characteristic are stored in advance, and the shift control and the lock-up control are performed based on these characteristics. For this control, the control unit UA
T is a main throttle opening signal from a main throttle opening sensor 61 that detects the opening of the main throttle valve 43 described below, and a sub throttle opening sensor 62 that detects the opening of the sub throttle valve 45. , And a vehicle speed signal (in the embodiment, a rotation speed signal of the propeller shaft 4) from a vehicle speed sensor 63 for detecting the vehicle speed.

Configuration of Brake Fluid Pressure Adjusting Mechanism Each wheel 1FR-1RR is provided with a brake 21FR-21RR. Brake fluid pressure is supplied to calipers (brake cylinders) 22FR to 22RR of the brakes 21FR to 21RR via pipes 23FR to 23RR.

The structure for supplying the brake fluid pressure to each of the brakes 21FR to 21RR is as follows. First, the depression force of the brake pedal 25 is boosted by a booster 26 using a hydraulic booster, and transmitted to a tandem-type master cylinder 27. The hydraulic pressure transmitted to the master cylinder 27 is applied to the left front wheel brake 21FL via a brake pipe 23FL connected to the first discharge port 27a of the master cylinder 27.
Is transmitted to the right front wheel brake 21FR via the brake pipe 23FR connected to the second discharge port 27b of the master cylinder 27.

Hydraulic fluid pressure from a pump 29 is supplied to the booster 26 via a pipe 28, and excess hydraulic fluid is returned to a reservoir tank 31 via a return pipe 30. A branch pipe 28a branches from the pipe 28, and an electromagnetic on-off valve 32 is connected to the branch pipe 28a.
Is connected. A pipe 33 is branched from the booster 26, and the pipe 33 is connected to an electromagnetic on-off valve 34 and a one-way valve 35 arranged in parallel with the on-off valve 34.

The branch pipe 28a and the pipe 33 are joined at a junction a, and the brake pipes 23RL and 23R for the left and right rear wheels are connected to the junction a.
R is connected. Electromagnetic on-off valves 36A and 37A are connected to the pipes 23RL and 23RR, respectively, and electromagnetic on-off valves 36B and 37B are respectively provided as outlet valves for relief passages 38L and 38R connected downstream of the valves 36A and 37A. It is connected.

Each of the valves 32, 34, 36A, 37A, 36B, and 37B described above is controlled by a traction control control unit UTR. That is, when the slip control as the brake control is not performed, the valve 32 is closed, the valve is opened, and the valve
B and 37B are closed, and valves 36A and 37A are opened. Thus, when the brake pedal 25 is depressed, the front wheel brakes 21FR, 21F
The brake fluid pressure is supplied to L via the master cylinder 27. Further, the working hydraulic pressure of the booster 26 is supplied to the rear wheel brakes 21RR and 21RL as brake hydraulic pressure via a pipe 33.

As will be described later, when the slip ratio of the rear wheels 1RR and 1RL as drive wheels to the road surface is increased and slip control as brake control is performed, the valve 34 is closed and the valve 32 is opened. Then, by the duty control of the valves 36A, 36B, 37A, 37B, the holding of the brake fluid pressure, the pressure increase and the pressure decrease are performed. More specifically, assuming that the valve 32 is closed, when the valves 36A, 36B, 37A, 37B are closed, the brake fluid pressure is maintained, the valves 36A, 37A are opened, and the valves 36B, 37B are opened. When is closed, the pressure rises, valves 36A and 37A close, and valves 36B and 3
When 7B is open, the voltage drops. The brake fluid pressure passing through the branch pipe 28a is prevented from acting as a reaction force on the brake pedal 25 by the action of the one-way valve 35.

When the brake pedal 25 is depressed during such slip control by the brake control, the hydraulic fluid pressure of the booster 26 corresponding to the depression is applied as brake fluid pressure via the one-way valve 35 to the rear wheel. Brakes 21RR and 21RL are supplied.

Configuration of Engine Generated Torque Adjusting Mechanism The control unit UTR performs the above-described throttle control together with the above-described brake control. For this reason, in the intake passage 41 of the engine, in addition to the main throttle valve 43 connected to the accelerator pedal 42, a sub-throttle valve 45 connected to a throttle opening adjustment actuator 44 is provided.
The sub-throttle valve 45 is controlled by the control unit UTR via the actuator 44. That is, when the main throttle valve 43 and the sub-throttle valve 45 are provided in series as described above, the throttle opening is ultimately governed by the opening of the smaller throttle valve. By controlling the opening degree of the engine 43, the torque generated by the engine can be appropriately reduced.

The control unit UTR for traction control controls the brake control by controlling the valves 32, 34, 36A, 36B, 37A and 37B and the throttle opening adjustment actuator 44 during the slip control. Throttle control. The control unit UTR receives signals from the wheel speed sensors 64 to 67 for detecting each wheel speed, a main throttle opening signal from the main throttle opening sensor 61, and a sub-throttle signal from the sub-throttle opening sensor 62. A mode for manually selecting a throttle opening signal, a vehicle speed signal from a vehicle speed sensor 63, an accelerator opening signal from an accelerator opening sensor 68, a steering angle signal from a steering angle sensor 69, and whether a sports mode is a normal mode or not. The mode signal from the selection switch 70 is input.

Further, the control unit UTR has an input interface for receiving each signal from each of the above sensors, a CPU, a ROM, and an RA.
M, a microcomputer, an output interface, and a drive circuit for driving the valves 32, 34, 36A, 37A, 36B, 37B and the actuator 44.The ROM stores control programs and various control programs required for traction control. A map and the like are stored, and various memories necessary for executing control are provided in the RAM.

Next, the details of the slip control by the control unit UTR will be described.

In the slip control, as described above, when the slip value of the drive wheel is about to exceed or exceeds the target slip value set separately, the drive torque is controlled so that the slip value of the drive wheel becomes the target slip value. It is what you do.

The drive torque control in the present embodiment is performed by the throttle control and the brake control as described above. In performing both of these controls, the slip value of the drive wheel is calculated, and the target slip value and the control start threshold value are set. Is set.

As the slip value of the driving wheel, a value obtained by subtracting the driven wheel speed from the driving wheel speed is used. More specifically, (the average of the left and right driving wheel speeds—the average of the left and right driven wheel speeds) is used as the slip value for the throttle control. Since it is performed separately for the drive wheels, (left drive wheel speed-average of left and right driven wheel speeds) is used for the left drive wheel, and (right drive wheel speed-left and right driven wheel speeds) for the right drive wheel. Average) is used.

As the target slip value, a target slip value STA for throttle control and a target slip value STB for brake control are separately set, and the control start threshold value is a small threshold value VS.
PB and a large threshold value VSPA (VSPA> VSPB) are set.

The outline of the throttle opening control and the brake control is as follows. That is, in the control unit UTR, drive wheel slip values for throttle control and brake control are calculated based on the wheel speeds input from the wheel speed sensors 64 to 67, and are also input to the control unit UTR. Based on the signals from the various sensors and switches 63 to 70,
The target slip values STA and STB and the control start thresholds VSPA and VSPB are set in accordance with maps stored in advance in Tables 1 and 2 described later. Then, when the drive wheel slip values for the throttle control and the brake control increase and exceed the small threshold value VSPB, the throttle control and the brake control are started, respectively. In the throttle control, the sub-throttle valve 45 is feedback-controlled via the actuator 44 so that the drive wheel slip value for the throttle control becomes the target slip value STA. In the brake control, the drive wheel slip value for the brake control is the target slip value. The brake hydraulic pressure to the left and right rear wheels 1RR and 1RL, which are the drive wheels, is feedback-controlled via the valves 36A, 36B, 37A and 37B so as to reach the value STB. In addition, if the slip value continues to increase even if the above throttle control and brake control are performed and the drive wheel slip value for throttle control reaches the large threshold value VSPA, the throttle opening is separately set at that time. The feedforward control is performed to rapidly reduce the value to the throttle sudden decrease control value SM, and then the above-described feedback control is performed again from the throttle opening rapidly decreasing state.

The feedback control in the throttle control and the brake control is performed based on two factors: a change ratio of the drive wheel slip value with respect to time, and a deviation of the drive wheel slip value from the target slip value.

Normal Control, Turning Control, and Delay Control Next, the normal control, turning control, and delay control in the present slip control will be described with reference to the flowchart shown in FIG.

In the present slip control, the traveling state of the vehicle is determined to be turning when the steering angle θ _H is 30 ° or more and straight traveling when the steering angle θH is less than 30 °, and the driving wheel slip value is set for straight traveling when traveling straight. Control (normal control) is performed so as to be the target slip value, and control is performed such that the driving wheel slip value is smaller than the target slip value for the straight running that is set for the turning travel during turning ( Turning control) is performed, and even if the turning traveling state ends, a delay control in which the shift to the normal control is delayed for a predetermined time to continue the turning control is performed.

In the embodiment shown in FIG. 2, the delay control is performed only when the sports mode is selected.
First, the wheel speeds V ₁ ~V ₄ in S1, steering wheel angle theta _H and selection mode signal is input, the slip value of the driven wheel based on the wheel speeds V ₁ ~V ₄ is calculated in S2, S3
It is determined whether or not the slip value of the drive wheel is equal to or greater than a predetermined value (the small threshold value VSPB in the present embodiment). enter.

In such slip control, first, it is determined whether or not the sport mode is selected in S4, and if it is not the sport mode, that is, if the normal mode is selected,
Proceeding to S5, it is determined whether or not the steering angle θ _H is 30 ° or more. If not, the vehicle is in a straight running state, and the above-described normal control is performed in S6. Control is performed.

If the sports mode is selected, it is determined in S7 whether the steering wheel angle is 30 ° or more.
At S8, the flag F is set to 1, and at S9, the above-described turning control is performed.
If θ _H is smaller than 30 °, it is determined whether or not the flag F is 1 in S10. If F = 1, it means that the turning travel has ended and the vehicle has started straight traveling. The timer is set to a predetermined time (1.5 seconds in this embodiment), the flag F is set to 0 in S12, the delay control is started, and the turning control is continuously performed in S9. After that, since F = 0, S10 to S
Proceed to 13 to determine whether the timer has reached 0 in S13,
If it is not 0, the process proceeds to S14, the time of the timer is reduced, and the turning control is continued in S9. Then, when the timer reaches 0 after the elapse of the predetermined time, the process proceeds from S13 to S15, and the normal control is performed. Incidentally, steering wheel angle theta _H is familiar with turning state turned over again 30 degrees, is directly turning control without shifting the subsequent normal control is continued before the prescribed time has elapsed after entering the delay control .

Target slip values STA, STB and control start thresholds VSPA, VS
PB Next, specific examples of the target slip values STA and STB and the control start thresholds VSPA and VSPB will be described based on Tables 1 and 2 below.

Table 1 is a map for determining the control start thresholds VSPA, VSPB and the correction coefficient K described below. As shown in this map, the control start thresholds VSPA, VSPB of this embodiment are determined.
Is the steering angle θ _H , the sports mode or the normal mode (MOD1 is the sports mode, MODE0 is the normal mode), whether it is a rough road (AKR1 is a rough road, AKR0 is a normal road), the accelerator opening ACP and the road surface μ (MU) is determined according to the map in Table 1 above.

Table 2 shows the standard STA (STAO) and standard STB (STBO).
Is determined by the STAO, as shown in this map.
And STBO are determined by the road surface μ. The correction coefficient K is determined from the map shown in Table 1 based on the steering angle θ _{H and the} like, and the target slip values STA and STB are determined by multiplying the STAO and STBO by the correction coefficient K.

STA = STAO × K STB = STBO × K As shown in the map of Table 1, the correction coefficient K is always the steering angle of the steering wheel | θ _H |
Steering angle | θ _H |
Is set to be smaller during a turning travel of 30 ° or more, which means that the target slip value in the above-described turning control is smaller than the target slip value in the normal control.

The road surface μ is equal to the vehicle speed sensor 63 in the present embodiment.
And the wheel speed sensors 64 and 65
Based on the vehicle body acceleration calculated from the rate of change of the front wheel speed, which is the driven wheel speed, which is the driven wheel speed, with respect to the average time,
It is estimated from a map as shown in FIG.

In addition, whether or not the road is bad is determined as appropriate based on the vibration at each wheel speed because the wheel speed vibrates due to unevenness of the road surface in the case of a bad road.

In the above embodiment, the delay control of the present invention is performed only when the sports mode is selected, and is not performed in the normal mode. This is because the normal mode is a stability-oriented mode, and if such a mode is selected, the counter steer running or the slalom running will be rarely performed. Is based on the idea that there will be very few.

Contrary to the above embodiment, the delay control may be performed only when the normal mode is selected, and may not be performed when the sports mode is selected. This is because the normal mode is a stability-oriented mode as described above, and it is better to control the vehicle so as to prevent spinning of the vehicle body as much as possible so that the behavior of the vehicle does not change. Therefore, in the case of this normal mode, It is desirable to perform delay control. On the other hand, since the sports mode is a driving-oriented mode and is generally selected by a senior driver, it is better to leave a large degree of freedom for the driver without performing much control on the vehicle side. It is good to consider that it is better not to perform delay control in this sport mode, or because the target slip value during turning is set higher in sport mode than in normal mode. In the sports mode, it is based on the idea that there is no problem even if the delay control is not performed.

Of course, the delay control may be performed in both the sports mode and the normal mode.

(Effects of the Invention) As described in detail above, according to the traction control device for a vehicle according to the present invention, the turning control based on the small target slip value is continued for a predetermined time even after the turning traveling state ends. Thus, it is possible to prevent a rise in the target slip value in a straight running state that occurs transiently during counter-steer running or slalom running as described above, and it is possible to avoid a decrease in running stability due to the rise in the target slip value.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of an automobile provided with one embodiment of the present invention, FIG. 2 is a flowchart showing control contents of one embodiment of the present invention, FIG. 3 is a diagram showing a map for determining a road surface μ, FIG. 4 is a diagram showing the relationship between the front-rear direction grip force, the cornering force, and the slip value. 1RL, 1RR ... Drive wheel, UTR ... Control means

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masao Hideshima 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (56) References JP-A-4-208648 (JP, A) JP-A-2 −38149 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B60T 8/58 F02D 29/02

Claims (1)

(57) [Claims] In order to prevent the slip of the drive wheel from becoming excessive due to the excessive drive torque, the drive torque of the drive wheel is controlled so that the slip value of the drive wheel becomes a target slip value. A traction control device for a vehicle, comprising: control means for setting the target slip value to be smaller than time and controlling the drive torque, wherein the control means sets the target slip value to a predetermined time after the end of turning. A traction control device for a vehicle, wherein the driving torque is controlled as a target slip value during cornering.