JP2663267B2 - Vehicle traction control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a traction control method for a vehicle, and detects idle running (wheel spin) of a driving wheel generated when the vehicle starts or accelerates, and outputs an engine output based on the detection. And a traction control method for a vehicle in which the above-mentioned control is performed to suppress the idling of the drive wheels. 2. Description of the Related Art Conventionally, especially when a vehicle is traveling on a road having a low friction coefficient such as an icy road, a snowy road, or a muddy road, idling of drive wheels generated at the time of starting or accelerating the vehicle is prevented, and the vehicle is started. There is known a traction control device that improves performance, acceleration, and running stability. In such a traction control device, for example, as disclosed in JP-A-59-68537, the wheel speed of a drive wheel is compared with the wheel speed of a driven wheel, and the wheel speed of the former is set to the wheel speed of a rear vehicle. When the speed becomes higher than the speed to some extent, it is determined that the driving wheels are idling, and the throttle opening of the engine is reduced to lower the engine output, thereby suppressing the idling of the driving wheels. However, in the conventional traction control, the throttle is closed at a constant speed at the time of starting the throttle control by detecting the idling of the drive wheels. Therefore, on a road surface having a relatively high friction coefficient μ, the throttle is excessively closed in the initial control, There was a risk that the acceleration at the start would be insufficient. (Object of the Invention) Accordingly, an object of the present invention is to provide a traction control method that performs throttle closing control according to a road surface condition to improve acceleration performance. (Object of the Invention) The present invention obtains an average acceleration from the time when the average speed of the left and right driving wheel speeds exceeds the threshold value to the speed equal to the pseudo vehicle body speed, and starts the throttle control as the average acceleration increases. The above object is achieved by increasing the throttle closing speed at the time. (Effects of the Invention) According to the present invention, it is possible to perform throttle control suitable for road surface conditions, and it is possible to improve start-up / acceleration. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the configuration of a traction control device mainly composed of a microcomputer used in the embodiment of the present invention, and FIG. 2 is a timing chart for explaining its operation. In FIG. 1, 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 supplied to an arithmetic circuit 3, and the vehicle speed EVv corresponding to the engine speed and the gear position at that time is calculated. You. 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 of these wheel speeds is calculated as a pseudo vehicle speed Vv representing a speed approximating the actual vehicle speed.
Given to. In the threshold setting circuit 12, the pseudo vehicle speed
By adding a constant value Vk to Vv, a throttle control threshold speed Vs as shown in FIG. 2 is created. Further, the pseudo vehicle speed Vv, the threshold speed Vs, and the reference speed Vr are calculated by the arithmetic circuit 13.
And the average acceleration from when the reference speed Vr exceeds the threshold speed Vs until the reference speed Vr exceeds the pseudo vehicle speed Vv
_G is calculated. Vehicle speed EV equivalent to these engine speeds
v, the reference speed Vr, the threshold speed Vs, the pseudo vehicle speed Vv, and the average acceleration _G are all input to the control logic circuit 14. The control logic circuit 14 also receives the output of a sensor 16 representing the amount of depression of an accelerator pedal 15.
The control logic circuit 14 drives the throttle drive mechanism 17 to perform throttle control based on these input signals, and controls the engine output when the vehicle starts or accelerates. FIG. 3 shows a flowchart of an engine output control routine executed by the control logic circuit 14, which will be described below with reference to FIG. First, when the vehicle starts, the accelerator pedal is depressed, thereby increasing the vehicle speed EVv corresponding to the engine speed.
At a time A when the reference speed Vr (the average speed of the drive wheel wheel speeds VdL and VdR) below Vv exceeds the threshold speed Vs, a throttle close command is issued and the throttle speed fixing flag is defeated (steps S1 and S2). ). Next, the reference speed Vr is the pseudo vehicle speed Vv
An average acceleration _G from the speed equal to the speed above the threshold speed Vs is calculated (step S3). Reference speed Vr
Assuming that the time from when V exceeds Vs to Vs is ΔT, _G =
(Vs−Vv) / Δt. The average acceleration _G thus calculated is compared with a predetermined value AG (step S4). And
If _G ≧ AG, determining the first velocity v ₁ is set the throttle closing speed from point A in advance (step S5). If _G <AG, _G is compared with another predetermined value BG (BG <AG) (step S6). If AG> G ≧ BG, the throttle closing speed from time A is set to a second predetermined value. Speed v ₂
(Step S7, v ₂ <v ₁ ). If further _{G <BG,} determining the third velocity v ₃ which sets the throttle closing speed from point A in advance (step _{S8, v 3 <v 2 <} v 1). That is, the throttle closing speed at the start of the throttle control is increased as the average acceleration increases. Next, the vehicle speed EVv corresponding to the engine speed is changed to the threshold speed Vs
And whether or not the EVv is in an accelerating state (step S9). If this determination is "YES",
Check the throttle speed fixed flag (step S10). If the flag is not set, the previously determined throttle closing speed
v _1, v close the throttle at any speed _2, v _3, to reduce the engine output (step S11). Next, it is determined whether or not the accelerator pedal depression amount is smaller than the control value (throttle control end condition) (step S12). If “NO”, the process returns to step S9. On the other hand, the vehicle speed EVv corresponding to the engine speed reaches a high peak at the time point B, and shifts from acceleration to deceleration.
Since the determination in S9 is "NO", a throttle speed fixing flag is set (step S13), a throttle opening signal is issued at a time point B, and the throttle is opened at a preset speed (step S14). It returns to step S9 again. Vehicle speed equivalent to engine speed decelerated from time B
EVv reaches a low peak at time point C, and then starts accelerating. At this low peak time point C, EVv ≧ Vs and EVv
Turns to acceleration, the determination in step S9 becomes "YES", and the process proceeds to step S10.Since the throttle speed fixing flag has already been set, the control proceeds to step S15.
From time point C, the throttle is closed at a preset speed. Then, the process returns to step S9 via step S12.
At the next high peak time point D of the vehicle speed EVv corresponding to the engine speed, the determination in step S9 becomes "NO" similarly to the time point B, so the throttle is opened in step S14 through step S13, and the flow returns to step S9 through step S12. Return. Since the vehicle speed EVv corresponding to the engine speed is lower than the threshold speed Vs at the next low peak time E, the determination in the step S9 at the time E is “NO”, and therefore, the process proceeds to the step S14 via the step S13. Keep the throttle open. And vehicle speed EV equivalent to engine speed
At time F when v exceeds the threshold speed Vs, the determination in step S9 becomes “YES”.
Move to S15, close the throttle at the set speed, and open the throttle at the next high peak point G. 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. As is apparent from the above description, in the present embodiment, the reference speed Vr calculated from the wheel speeds VdL and VdR of the driving wheels in the initial stage of the throttle control is based on the pseudo vehicle speed Vv from the speed equal to the pseudo vehicle speed Vv. Calculate the average acceleration _G until it exceeds the threshold speed Vs set by
As the average acceleration _G increases, the throttle closing speed in the first (from the point A to the point B) throttle closing control is increased, so that the throttle control suitable for the road surface condition can be performed, and the start / acceleration can be improved. Can be planned. Further, by using the average acceleration as described above, a malfunction due to a noise signal included in the driving wheel speed can be avoided. Further, in the present embodiment, the throttle control based on the comparison between the reference speed Vr calculated and set from the wheel speeds VdL and VdR of the driving forest and the threshold speed Vs set in relation to the actual vehicle speed,
Since the throttle is controlled by comparing the vehicle speed EVv corresponding to the engine speed and the threshold speed Vs only after the control start time A, the slip of the driving force transmission system must be completely excluded from the control system. In consideration of the delay in the response of the engine speed to the opening and closing of the throttle, the throttle opening and closing is determined by taking into account whether the vehicle speed EVv corresponding to the engine speed is in an accelerating state or a decelerating state.
Since it is performed early, smooth traction control can be achieved. In the above-described embodiment, the wheel speed Vd of the left and right drive wheels is used as the reference speed Vr used to determine the start of traction control.
Instead of calculating the average speed of L and VdR, instead of this reference speed Vr, the lower wheel speed (low select) or the higher wheel speed (high select) of the wheel speeds VdL and VdR is used. ) May be selected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of a traction control device used in the embodiment of the present invention, FIG. 2 is a timing chart for explaining its operation, and FIG. 3 is a flowchart of a throttle control routine. is there. 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 Average acceleration calculation circuit 14 Control logic circuit 16 Accelerator pedal depression amount sensor 17 Throttle drive mechanism

Claims (1)

(57) [Claims] A traction control method comprising detecting idle running of a drive wheel generated when a vehicle starts or accelerating, and performing throttle control of an engine based on the detection to suppress idle running of the drive wheel. From the speed at which the average speed of the vehicle speed is equal to the pseudo vehicle speed, to the average speed above the vehicle speed and before exceeding a threshold speed obtained by adding a constant value to the vehicle speed, the average acceleration is obtained. A traction control method for a vehicle, characterized in that the throttle closing speed at the start of the throttle control is increased as the throttle control becomes larger.