JP2000344086A - Traction control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain lag of traction control by obtaining this time reference speed according to a designated wheel speed which is higher than the minimum wheel speed and lower than the maximum wheel speed when the preceding car speed is equal to or higher than a designated value. SOLUTION: Output signals from the respective wheel speed sensors 10-10z of wheels WFL-WRR are input through an A/D converter 12 to a processor 24 in this control device 100, and the wheel speeds are detected by using a program of a ROM 16 to conduct various control. In traction control, when a deviation between a reference wheel speed and a specified wheel speed exceeds a designated value, an actuator ACT for driving a brake is driven to brake the wheel of the high speed side, thereby restraining slip. When the preceding car speed is equal to or higher than a designated value, this time reference speed is obtained according to a designated wheel speed which is higher than the minimum wheel speed and lower than the maximum wheel speed. This car speed is the preceding reference speed or the speed of a vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traction control device for controlling traction of a plurality of wheels according to a reference speed.

[0002]

2. Description of the Related Art A conventional traction control device is disclosed in Patent 28
No. 03472. The present apparatus recognizes a case where the speed difference between the left and right driven wheels exceeds a predetermined value as an abnormality of the wheel speed sensor, and calculates an traction control reference speed from a wheel speed greater than the minimum wheel speed when the wheel speed sensor is abnormal.

[0003]

However, since the detection at the time of abnormality is based on the speed difference between the left and right driven wheels, the abnormality is not detected until the speed difference is obtained, and a delay occurs in the traction control. An object of the present invention is to provide a traction control device in which a delay in traction control is suppressed as compared with the related art.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a traction control device for traction-controlling a plurality of wheels in accordance with a reference speed. Is determined based on a predetermined wheel speed that is larger than the minimum wheel speed and smaller than the maximum wheel speed. When the vehicle speed is equal to or higher than the predetermined value, even if the reference speed based on the minimum wheel speed is not used,
Traction control can be performed smoothly,
A reference speed is obtained from the predetermined wheel speed.

In such a case, even when the wheel speed is abnormal and the output value is zero, the traction control can be started, so that the delay of the traction control can be suppressed.

The vehicle speed is a previous reference speed or the speed of the vehicle, and the speed of the vehicle may be calculated from the reference speed, a wheel speed sensor, a G sensor, a speed sensor, or the like.

Preferably, the predetermined wheel speed is a wheel speed that is the second lowest wheel speed after the lowest wheel speed.

[0008] It is preferable that the predetermined wheel speed is a wheel speed next to the minimum wheel speed and next smaller.

[0009] All the wheels of the vehicle may be traction-controlled drive wheels.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A traction control device according to an embodiment will be described below. The same reference numerals are used for the same elements or elements having the same functions, and overlapping descriptions are omitted.

FIG. 1 is a schematic configuration diagram of a vehicle equipped with a traction control device according to an embodiment.

This vehicle has four wheels (front wheels W _FL , W _FR , rear wheels W _RL , W W) provided rotatably with respect to a vehicle body BDY.
_RR ). Wheel speed sensors 10, 10x, 10y, and 10W correspond to the wheels W _FL , W _FR , W _RL , and W _RR , respectively.
z are provided, and the output is proportional to the wheel speed. Here, the wheel speed sensors 10, 10x, 10
For y and 10z, the rotational speed of the wheel is detected electrically / magnetically or optically, and an AC signal corresponding to the rotational speed is output.

Outputs from the sensors 10, 10x, 10y, and 10z are output from an ECU (electronic control unit), an ABS (anti-lock brake system),
It is input to a control device 100 such as a TRC (Traction Control) system computer.

The AC signals output from the sensors 10, 10 x, 10 y, and 10 z are input to the processor 24 in the control device 100 via the A / D converter 12. A
The / D converter 12 samples the AC signal from the wheel speed sensor at a predetermined sampling timing, converts the signal into a digital signal, and supplies the digital signal to the processor 24. The processor 24 processes digital signals using a program stored in the ROM 16, detects wheel speeds, and performs various controls. The processor 24, the ROM 16, the RAM 18
Can be constituted by a microcomputer.

The control device 100 obtains the wheel speeds v _FL , v _FR , v _RL , v _RR of each wheel based on the input wheel speed information and the like, and displays the vehicle speed calculated from the obtained wheel speeds. The brake control is executed based on the wheel speeds v _FL , v _FR , v _RL and v _RR .

Drive means for performing brake control;
And each wheel W_FL, W_FR, W_RL, W _RRNo brake
B_FL, B_FR, B_RL, B_RRIs provided. Brake B
_FL, B_FR, B_RL, B_RRIs an actuator for driving a brake
Wheel ACT_FL, W_FR, W_RL, W
_RRTo the braking force. For brake control, ABS
Wheel W_FL, W_FR, W_RL, W_RRLock timing
Control, slip suppression control by TRC, posture stabilization
Vehicle behavior control, etc.
The step-up control will be described.

FIG. 2 illustrates the execution of traction control.
It is a flowchart for the. Four-wheel drive (4WD) vehicles
Is a four wheel W_FL, W_FR, W_RL, W_RRCan be a driving wheel
Both. That is, in the four-wheel drive mode,
Wheel W_FL, W_FR, W_RL, W _RRBecomes the drive wheel, and the two wheels
In the driving mode, the front wheels W_FL, W_FROr rear wheel
W_RL, W_RRAre the driving wheels. Here, the four-wheel drive mode
This will be explained in the mode.

During traveling on a rough road in the four-wheel drive traveling mode, the left front wheel W _FL shown in FIG. 1 slips on the road surface to slip and the other wheels W _FR , W _RL , and W _RR do not slip. Is in contact with the road surface. In this case, during the traction control, the brake B is driven by driving the brake driving actuator ACT.
_The slip is suppressed by operating the _FL and applying a braking force to the left front wheel W _FL to stop the rotation.

In order to perform this control, it is necessary to detect a slip state. If the wheel speed v _FL of the wheel is significantly higher than the reference wheel speed (reference speed) v _STD , this can be determined as a slip state. In the traction control, when the deviation between the reference wheel speed v _STD and the specific wheel speed exceeds a predetermined value, a braking force is applied to the high-speed wheel (brake is applied) to suppress slip.

More specifically, the wheel speed deviation Δv (= v_FL-V
_RR) Exceeds the predetermined deviation, the control device 100
W_FLRecognizes that the vehicle is in the slip state and activates the brake
By driving the actuator ACT for
Key B_FLThe left front wheel W _FLThis time
Stop rolling. In other words, during traction control
And the control device 100 determines based on the detected wheel speed and the like.
Four wheels W_FL, W_FR, W_RL, W_RRTo prevent slipping
Controls actuator ACT.

As described above, the traction control is executed based on the specific reference wheel speed v _{STD (n)} (S9).

If the system is failing (S1), fail processing is performed and traction control is prohibited (S2).

When the vehicle is not failing, the traction control is executed as necessary as described above. To execute the traction control, the control device 100 controls the four wheel speeds v _FL , v _FR , v _RL , v _RR to reference wheel speed v
_{Find STD (n)} .

The current reference wheel speed v _{STD (n)} is obtained based on the predetermined wheel speed v ₀ as follows.

(1) The minimum wheel speed (smallest of the four wheel speeds) v _min is relatively low (for example, less than 5 km / h) (S3), and it is determined that the wheel speed sensor or the like is abnormal. Alternatively, in the case of estimation (S4), the wheel speed v _NEXT next to the lowest wheel speed v _min is used for v ₀ (S5).

(2) Even when the previous reference wheel speed v _{STD (n-1)} is equal to or higher than a predetermined value (for example, 60 km / h) (S7), v
_A wheel speed v _NEXT next to the lowest wheel speed v _min is used as 0 (S5).

(3) When the previous reference wheel speed v _{STD (n-1)} is smaller than a predetermined value (S7), the minimum wheel speed v _min is used for v ₀ (S8).

[0028] (4) in the case of coasting and ABS control secondary is, using the maximum wheel speed as v _0.

If the vehicle speed is equal to or higher than the predetermined value (S7), the wheel speed v _{NEXT is changed} to v _0.
The traction control can be smoothly performed even if the reference wheel speed v _{STD (n)} based on this is used. In step (S6), a reference wheel speed v _{STD (n)} to be used for traction control is obtained using v ₀ . This can be obtained by the following calculation or a look-up table method using a map in which these are previously associated.

In such a case, even if the wheel speed is abnormal and the output value is zero, the traction control (S9) can be started, so that the delay of the traction control can be suppressed. .

In the above case (3), v ₀
May be used _NEXT, in this case (1) and (2) at v ₀ as v _NEXT next using a small wheel speeds of.
In any case, the predetermined wheel speed v _NEXT is larger than the minimum wheel speed v _{min and} smaller than the maximum wheel speed v _max .

The minimum wheel speed v _min may be smaller than the smaller one of the maximum rear wheel speed and the minimum rear wheel speed + Δv _F compared with the minimum front wheel speed.
Here, Δv _F is the smaller of the left and right front wheel speed difference and 3 km / h.

Furthermore, the (1), in the case of (2) or (4), using the maximum value of the rear wheel speed as v ₀ if there is an abnormality in the wheel, when there is an abnormality in the rear wheel Is v ₀
Is used as the maximum value of the front wheel speed. In the above case (3), using the minimum value of the rear wheel speed as v ₀ if there is an abnormality in the wheel, when there is an abnormality in the rear wheels uses a minimum value of front wheel speed as v _0.

As described above, the reference wheel speed v _{STD (n)} is obtained based on the predetermined wheel speed v _{0 and the} like, and the calculation method thereof is as follows.

[0035] When noise is detected in the (A) system, in the case of initial start-up such systems, reference wheel speed v _{STD (n)} to v using the maximum wheel speed not _zero.

(B) Immediately after returning from the shutdown of the system or when the system is started, the largest one of the maximum wheel speed and the previous reference wheel speed v _{STD (n-1)} is set to the current reference wheel speed v _{ST D (n)} .

(C) In cases other than these two cases (A, B), v ₀ , v _{T (n-1)} -αdwΔt, v _{T (n-1)} + αupΔ
t is the current reference wheel speed v
_{STD (n)} . Here, the coefficient αdw is such that v _{T (n-1)} is 2 km / h
In the above case, 1 is satisfied, and in other cases, 1.15 is satisfied. The coefficient αup satisfies ₁ when v _{T (n-1)} is 2 km / h or more, and satisfies 5 in other cases. Note that Δt is an operation (sampling) cycle.

In the case of abnormal wheel speed, noise, or momentary interruption of the sensor, the maximum wheel speed of the front and rear wheels and the minimum wheel speed of the front and rear wheels are determined to be normal for each of the front wheel pair and the rear wheel pair. The wheel speed may be adopted.

As described above, the traction control device controls the plurality of wheels W _FL , W _FR , W _RL , and W _RR according to the reference speed v _{STD (n).} When the vehicle speed v _{STD (n-1)} is equal to or higher than a predetermined value (for example, 60 km / h), the current reference speed v _{STD (n)} is set to be larger than the minimum wheel speed v _{min and the} maximum wheel speed v
_It is obtained based on a predetermined wheel speed v _NEXT smaller than _max .

The vehicle speed is the previous reference speed or the speed of the vehicle, and the speed of the vehicle may be calculated from the reference speed, a wheel speed sensor, a G sensor, a speed sensor, or the like.

[0041] predetermined wheel speed v _NEXT may be the next to a small wheel speed of the lowest wheel speed v _min, the lowest wheel speed v _min
The wheel speed may be the next to the next lower wheel speed. Further, all of the wheels W _FL , W _FR , W _RL , and W _RR of the vehicle can be traction-controlled drive wheels.

[0042]

As described above, the traction control device of the present invention can suppress the delay of the traction control as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a vehicle equipped with a traction control device according to an embodiment.

FIG. 2 is a flowchart for explaining execution of traction control.

[Explanation of symbols]

 W_FL, W_FR, W_RL, W_RR... drive wheel, 100 ... control device,
B_FL, B_FR, B_RL, B _RR…brake.

Continued on the front page (72) Inventor Munefumi Hosomi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Tosumi Ishikawa 2-1-1 Asahimachi, Kariya City, Aichi Prefecture Inside Aisin Seiki Co., Ltd. (72 ) Inventor Yasuhito Ishida 2-1-1 Asahi-cho, Kariya-shi, Aichi F-term in Aisin Seiki Co., Ltd. (Reference) 3D046 BB29 EE01 GG02 JJ03 JJ06 KK12

Claims (5)

[Claims] 1. A traction control device for traction-controlling a plurality of wheels according to a reference speed, wherein when a previous vehicle speed is equal to or higher than a predetermined value, a current reference speed is set higher than a minimum wheel speed and lower than a maximum wheel speed. A traction control device characterized in that it is determined based on wheel speed. 2. The traction control device according to claim 1, wherein the vehicle speed is a previous reference speed or a vehicle speed. 3. The wheel speed according to claim 1, wherein the predetermined wheel speed is a wheel speed that is the second lowest wheel speed after the minimum wheel speed.
A traction control device according to claim 1. 4. The traction control device according to claim 1, wherein the predetermined wheel speed is a wheel speed that is next to the minimum wheel speed and is next smaller. 5. The traction control device according to claim 1, wherein all wheels of the vehicle can be drive wheels that are subjected to traction control.