JP2992551B2 - Vehicle traction control method - Google Patents

Description

The present invention relates to a traction control method for a vehicle having an automatic transmission.

(Prior art) Conventionally, especially when a vehicle travels on a low friction coefficient road surface (low μ road) such as a frozen road, a snowy road or a muddy road,
2. Description of the Related Art There is known a traction control device that prevents a slip of a drive wheel at the time of starting or accelerating a vehicle, thereby improving startability, acceleration, and running stability of the vehicle. In such a device, the wheel speed of the driving wheel is compared with the wheel speed of the driven wheel, and if the speed difference between the two exceeds a certain value, the electronic control unit (ECU) determines that the driving wheel is slipping. Then, the throttle designated value for the throttle drive mechanism is reduced, whereby the accelerator opening of the engine is reduced, the engine output is reduced, and traction is restored.

On the other hand, as one of the automatic transmissions of the vehicle, various actuators such as a clutch actuator, a select actuator, and a shift actuator are added to a parallel gear shaft type manual transmission without using a normal torque converter, and these are used by a driver. Instead, there is a kind of robot system that automatically shifts by ECU command.

Meanwhile, when traction control is performed in a vehicle having the above-described automatic transmission, conventionally, the timing of shifting is determined based on an accelerator command value output from an ECU and a driven wheel speed. Therefore, when the driver steps on the accelerator pedal to accelerate, the traction control starts when the drive wheels slip and the ECU
Lowers the throttle command value, so that the shift is performed. Therefore, there is a drawback that the driver who tries to accelerate is given a feeling of strangeness, and the clutch disengagement mode gives a loose feeling.

(Object of the Invention) In view of the above, the present invention provides a vehicle equipped with an automatic transmission as described above so that a shift is not performed even if traction control is started due to slip of a drive wheel and a throttle command value is reduced. Accordingly, an object of the present invention is to provide a traction control method that does not give the above-mentioned uncomfortable feeling or a feeling of looseness to a driver.

(Structure of the Invention) The present invention is characterized in that during traction control, the shift timing in the automatic transmission is determined based on an accelerator pedal depression amount and a driven wheel speed.

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

FIG. 1 shows a configuration of a traction control device for a vehicle mainly comprising a microcomputer applied to the embodiment of the present invention. In the figure, 1 is an engine speed sensor, 2 is a sensor for detecting the gear position of the transmission,
The outputs of these sensors 1 and 2 are given to an arithmetic circuit 3 of an electronic control unit (ECU) 30 and the current engine speed Ne
The vehicle speed EVv corresponding to the engine speed corresponding to the gear position and the gear position is calculated.

On the other hand, the rotation speed of the left and right drive wheels is determined by the rotation speed sensor 4L,
The wheel speeds VdL and VdR of the drive wheels are calculated by the arithmetic circuits 5 and 6 respectively. These wheel speeds VdL and VdR are given to the arithmetic circuit 7, and the average value of these wheel speeds is used as the control start reference speed Vr (= (VdL + VdR) / 2).
Is calculated as The rotation speed of the left and right driven wheels is
The rotational speed sensors 8L and 8R detect the rotational speeds, and the arithmetic circuits 9 and 10 calculate the wheel speeds VnL and VnR of the driven wheels, respectively. These wheel speeds VnL and VnR are determined by the high select circuit 11.
The wheel speed on the high speed side among the wheel speeds of these driven wheels is calculated as a pseudo vehicle speed Vv representing a speed approximating the actual vehicle speed, and this speed Vv is supplied to the threshold setting circuit 12. Can be The threshold value setting circuit 12 adds a constant value Vk to the pseudo vehicle speed Vv to generate a control threshold value Vs. The engine speed Ne, the vehicle speed EVv corresponding to the engine speed, the reference speed Vr, and the threshold value Vs are all input to the control logic circuit 13. Also, this control logic circuit
A sensor 13 represents a depression amount a of an accelerator pedal 14.
15 outputs are also input. The control logic circuit 13 drives the throttle drive mechanism 16 to perform throttle control based on these input signals, and controls the engine output when the vehicle starts or accelerates.

On the other hand, 17 is a clutch actuator for selecting two positions for connecting and disconnecting the clutch, 18 is a select actuator for selecting three left and right positions of the shift lever of the transmission, and 19 is a shift actuator for shifting the shift lever to three front and rear positions. Each of these actuators is of a hydraulic type and is operated by the control logic circuit 3 through a number of on-off valves and flow path switching valves 20a to 20n, whereby the transmission is in the first to fifth speeds, N (neutral ) And R (reverse).

FIG. 2 shows a flowchart of a traction control routine executed by the control logic circuit 13, which will be described below with reference to the timing chart of FIG.

First, when the vehicle starts, the accelerator pedal is depressed to the maximum amount, whereby the vehicle speed EVv corresponding to the engine speed increases, and the reference speed Vr (the average speed of the drive wheel speeds VdL and VdR) falls below this speed EVv. At the time point A when the threshold value Vs is exceeded, a throttle close command is issued, and the pseudo vehicle speed at that time
The control is started at the throttle return speed determined by Vv and the gear position, and the engine output is reduced (step S
2). The engine speed-equivalent speed EVv reaches a high peak at a time point B and shifts from acceleration to deceleration. In step S3, it is determined whether or not the engine speed-equivalent vehicle speed EVv is higher than a threshold value Vs. If the determination is "YES", the flow proceeds to the next step S4, where it is determined whether or not the vehicle speed EVv corresponding to the engine speed is in an accelerating state. EVv is still higher than the threshold value Vs, and deceleration starts after high peak time B, so the determination in step S4 is "NO", and at time B, a throttle opening signal is issued, and the vehicle body acceleration and gear position at that time are determined. The throttle is opened at the speed determined by (Step S5). If the determination in step S3 is "NO", the process directly proceeds from step S3 to step S5 to open the throttle.

Next, in step S6, it is determined whether or not the accelerator pedal depression amount exceeds a control value.
Return to 3. The vehicle speed EVv corresponding to the engine speed, which has been decelerating from time B, reaches a low peak at time C and starts to accelerate. At this low peak time C, EVv ≧ Vs and EVv starts to accelerate. The determinations in S4 are both "YES", and control proceeds to step S7 to close the throttle. Then, the control returns to step S3 via steps S7 to S6. At the next high peak time D of EVv, the determination of step S3 is "YES" and the determination of stap S4 is "NO" similarly to time B, so the process proceeds to step S5, the throttle is opened, and the process returns to step S3 via step S6. Return. On the other hand, at the next low peak E of the speed EVv, since the value is below the threshold Vs, the determination in step S3 is “NO”.
Then, the process proceeds to step S5 to keep the throttle open. When the speed EVv reaches the threshold value Vs at the point F, the determinations in steps S3 and S4 are both "YES". Therefore, the process proceeds to step S7, the throttle is closed, and the next high peak point G
Open the throttle with. By alternately opening and closing the throttle in this manner, the vehicle speed EVv corresponding to the engine speed approaches the pseudo vehicle speed Vv, and the desired traction control can be achieved.

Thus, in the present embodiment, the wheel speeds VdL, Vd
The engine output control based on the comparison between the reference speed Vr calculated and set from dR and the threshold value Vs set in relation to the actual vehicle speed (follower wheel speed) is limited to the control start time A only, and immediately thereafter, the engine speed is controlled. Since the throttle is controlled by comparing the vehicle speed EVv and the threshold value Vs, the slip of the driving force transmission system can be completely eliminated from the control system, and the response of the engine speed to the opening and closing of the throttle can be reduced. Taking into account the delay, opening and closing the throttle early, taking into account whether the vehicle speed EVv equivalent to the engine speed is in an accelerating state or a decelerating state, is performed earlier, so that smooth traction control is achieved. Can be.

Next, FIG. 4 shows a flowchart of a transmission control routine executed by the control logic circuit 13 after the above-described traction control is started.

First, it is determined in step S10 whether traction control has been started. If not, normal control is performed in step S11. When it is determined that the traction control has been started, the accelerator pedal depression amount a and the pseudo vehicle speed Vv (= driven wheel speed) are detected in step S12, and the process proceeds to step S13. In step S13, when the accelerator pedal depression amount a is less than the predetermined value A1 (a ≦ A1) and when the speed Vv is less than the predetermined value B1 (Vv ≦ B1), the process proceeds to step S14 and the gear of the transmission is shifted. Decide the position to 2nd gear and change gears, next step
Unless the end of the traction control is determined in S15, the process returns to step S12. When the determination in step S13 is “NO”, the process proceeds to step S16, where A1 <a ≦ A2 (A1 <A2), and
If B1 <Vv ≦ B2 (B1 <B2), the gear position is determined to be the third speed in step S17, and the speed is changed. Similarly, A2a ≦ A3 (A2 <A
If 3) and B2 <Vv ≦ B3 (B2 <B3), step S1
Proceeding to 7, S18, the gear position is determined to be the fourth speed in step S19, and the speed is changed. If A3 <a and B3 <Vv, step
In S20, the gear position is determined to the fifth speed, and the speed is changed. When the traction control ends, the control routine of FIG. 4 ends.

(Effects of the Invention) As is clear from the above description, according to the present invention, during traction control, the shift timing in the automatic transmission is determined by the depression amount a of the accelerator pedal and the driven wheel speed (= Vv). Therefore, when the driver depresses the accelerator pedal to accelerate, even if the throttle command value is reduced due to slippage of the drive wheels, no shift is caused by this, so that the driver feels strange or sluggish. The fear is eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a vehicle traction control device applied to the embodiment of the present invention, FIG. 2 is a flowchart of a traction control routine, FIG. 3 is a timing chart, and FIG. 4 is a transmission during traction control. It is a flowchart of a control routine. 1 ... engine speed sensor 2 ... gear position sensor 3 ... engine speed equivalent vehicle speed calculation circuit 4L, 4R ... drive wheel rotation speed sensor 7 ... reference speed calculation circuit 8L, 8R ... driven wheel rotation speed sensor 11 High select circuit 12 Threshold setting circuit 13 Control logic circuit 15 Accelerator pedal depression amount sensor 16 Throttle drive mechanism 17 Clutch actuator 18 Select actuator 19 Shift actuator 30 …… Electronic control device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatezo Kuroyanagi 8 Fujisawa-shi, Kanagawa Prefecture, Isuzu Motors Co., Ltd. Fujisawa Plant (72) Inventor Hideaki Watanabe 8 Tsuzura, Fujisawa-shi, Kanagawa Isuzu Motors Stock (72) Inventor Katsuya Miyake 5-4-1, Higashi 5-chome, Hanyu-shi, Saitama Prefecture Akebono Brake Industry Co., Ltd. (72) Inventor Yoshiaki Yabe 5-4-71 Higashi, Hanyu-shi, Saitama Stock Company In Akebono Brake Central Technical Research Institute (72) Inventor Shigeki Moride 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited (56) References JP-A-62-106160 (JP, A) JP-A-63- 263138 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B60K 41/08 F02D 29/02 311

Claims (1)

(57) [Claims] 1. A traction control method for a vehicle equipped with an automatic transmission, wherein a slip of a driving wheel generated at the time of starting or accelerating is suppressed by controlling a throttle opening. A plurality of threshold values are set for the respective speeds, and the shift timing of the automatic transmission is set such that the shift timing of the automatic transmission shifts to a higher speed side as the accelerator pedal depression amount and the driven wheel speed exceed a large threshold value. A traction control method for a vehicle, wherein the traction control method is determined based on an amount and a driven wheel speed.