JPH05280387A - Traction controller - Google Patents

Abstract

PURPOSE:To restrict blowing up of an engine by detecting a road surface resistance immediately before starting a vehicle. CONSTITUTION:Before starting a vehicle, a power-driven motor 4 is energized to steer rear wheels, so a friction coefficient of a road surface is detected by a CPU 2 based on a steering force at the time. By controlling an engine output when the vehicle is started in accordance with the detected friction coefficient of the road surface, stable traction control is realized in a transitive period from starting till stationary run, thereby a comfortable riding feeling similar to that under normal run can be felt from the time of starting on without feeling uncomfortableness caused by void run of the wheels.

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 which detects road surface resistance immediately before starting and suppresses engine upswing.

[0002]

2. Description of the Related Art A traction control device for optimally controlling the driving force of driving wheels in accordance with driving conditions prevents the wheels from idling by automatically controlling the engine output within a range of driving force that a tire can transmit to a road surface. Therefore, it is possible to stably secure the gripping force in the lateral direction and the front-rear direction of the tire even under the road surface condition where slipping is easy, and it is possible to obtain excellent directional stability. This type of conventional traction control device monitors the occurrence of idling with a sensor that monitors the wheel speed and the vehicle speed, and when idling occurs, adjusts the opening of a throttle valve according to a command from the CPU to throttle the engine output. With this configuration, appropriate control is performed according to the friction coefficient of the road surface during acceleration.

[0003]

The above-mentioned conventional traction control device is configured so that, during the traveling of the vehicle, whether the tire is slipping due to the difference between the wheel speed and the vehicle body speed, that is, the engine output is always transmitted to the road surface by the tire. The friction coefficient of the road surface can be indirectly detected by determining whether it is within the range of the obtained driving force, but when the vehicle is started from a stopped state, the road surface resistance immediately before the start is completely unknown, and therefore, Until the vehicle actually starts moving and the friction coefficient of the road surface can be actually detected, it is necessary to perform traction control without knowing the friction coefficient of the road surface for a very short period. There was a problem that when starting from a road where the friction coefficient of the road surface is extremely small, it is easy to experience the discomfort caused by the wheels spinning.

At present, since there is no way to measure the friction coefficient of the road surface when the vehicle is stopped, the friction coefficient of the road surface obtained from the progress of traction control immediately before the stop is temporarily stored in a buffer memory or the like. Even if I did, I could not cope with the case where the friction coefficient of the road surface changed due to rainfall after stopping,
Since it was not possible to know the road surface resistance immediately before starting, there was a problem that it was not possible to desire complete traction control when starting.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems and is a traction control for preventing wheel idling by automatically controlling the engine output within a range of driving force that the wheel can transmit to the road surface. In the device, friction coefficient detecting means for detecting a friction coefficient of a road surface before starting the vehicle, and engine output control for controlling an engine output when the vehicle starts according to a friction coefficient of the road surface detected by the friction coefficient detecting means. The first feature is that the friction coefficient detection means steers the stopped wheel until the direction is changed, and the steering force required by the steering means. A second feature is to have a friction coefficient estimating means for estimating the friction coefficient of the road surface.

[0006]

The present invention detects the friction coefficient of the road surface before starting the vehicle and controls the engine output when the vehicle starts according to the detected friction coefficient of the road surface.
Achieves stable traction control even in the transitional period when the vehicle shifts from start to steady running. In addition, by steering the stopped wheel until the direction changes, and estimating the friction coefficient of the road surface from the steering force required at that time, the friction coefficient of the road surface can be accurately grasped immediately before starting, and Make traction control accurate and reliable.

[0007]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic configuration diagram showing an embodiment of a traction control device of the present invention, and FIG.
FIG. 3 is a flowchart for explaining the operation of estimating the friction coefficient of the road surface by the CPU shown in FIG. 1, FIG. 3 is a flowchart for explaining the traction control operation at the time of starting by the CPU shown in FIG. 1, and FIG. 6 is a flowchart for explaining a start detection operation by the CPU shown in FIG.

The traction control device 1 shown in FIG.
A CPU 2 which is mounted on a manual transmission vehicle of a four-wheel steering (4WS) system and which controls the entire vehicle such as four-wheel steering, traction control or fuel injection control.
Controls the engine 3, which is the power source, and the electric motor 4 for steering the rear wheels, based on information from various sensors. In the embodiment, the CPU 2 corresponding to the friction coefficient estimating means and the electric motor 4 corresponding to the steering means constitute the friction coefficient detecting means for detecting the friction coefficient of the road surface before starting the vehicle, and are detected. The CPU 2 and the throttle valve (not shown) constitute the engine output control means for controlling the engine output when the vehicle starts according to the friction coefficient of the road surface.

As a sensor for sending various information to the CPU 2, a vehicle speed sensor 5 for detecting the speed of the vehicle body, a wheel speed sensor 6 for detecting the wheel speed, or a gear position sensor 7 for detecting the gear position, and a front wheel A steering sensor 8 for detecting a steering angle, an accelerator opening sensor 9 for detecting an accelerator opening, and a clutch opening sensor 1 for detecting a clutch opening.
There is 0 etc. In addition to this, a doorknob sensor 11 for monitoring whether or not the driver touches the doorknob on the driver's side from outside, and a clutch for detecting that the clutch is engaged and power transmission is performed. A meat sensor 12, a differential transformer 13 for detecting the steering angle of the rear wheels by the electric motor 4, a vehicle height sensor 14 for detecting the distance from the ground surface to the vehicle body for each of the four wheels, etc. are connected to the CPU 2. ..

A method of detecting the friction coefficient of the road surface from the stopped state to the start will be described below. Since the vehicle shown in the embodiment adopts the four-wheel steering system for steering the rear wheels, the steering load at the time of lane change at high speed and parking in the side-by-side parking is considerably reduced. The steering angle of the rear wheels is changed by a rod (not shown) that is driven forward and backward by the electric motor 4, and the extension length of the rod is detected by the differential transformer 13 and is taken into the CPU 2 as steering angle information of the rear wheels. ..

First, in step (101) shown in FIG. 2, it is judged whether or not the driver has opened the door on the driver's side from the outside, and the door has been opened from the output of the door knob sensor 11 on the driver's side. If you understand the following steps (1
In 02), it is determined whether the engine 3 has been started, and if it is determined that the engine 3 has not started, then in the next step (103), it is determined whether the wheel speed is zero, that is, the vehicle is still stopped. It is determined whether or not. Therefore, if the vehicle starts immediately after the door is opened, the friction coefficient of the road surface is not estimated from the viewpoint of risk prevention, and the process directly proceeds to the main routine. Then, when it is determined that the wheel speed is zero while the engine 3 is stopped, that is, the vehicle is in a stopped state, it is determined in the next step (104) whether one side of the wheel is riding on the road shoulder. Done. This determination is made according to the outputs of the vehicle height sensors 14 arranged on the four wheels, and when only one side wheel is riding on the road shoulder, the main friction coefficient is not estimated from the viewpoint of risk prevention, without estimating the road friction coefficient. Go to routine.

When it is found that the four wheels are on a substantially flat plane, the electric motor 4 is energized in the following step (105). As a result, the rear wheel steering rod is driven by the electric motor 4, and the rear wheel steering is started. At this time, as shown in step (106), the CPU 2 monitors the output of the differential transformer 13, and until the actual output of the differential transformer 13 is obtained, as shown in step (107), the electric motor 4 output is increased. And
When an output is obtained from the differential transformer 13 at a certain time point, the road surface resistance against the rear wheel steering is found from the energized state of the electric motor 4 at that time, and the road surface friction coefficient is estimated from this road surface resistance. When the friction coefficient of the road surface is determined in step (108), the following step (109)
At, the electric motor 4 is immediately stopped and the rear wheel steering is stopped. Therefore, the rear wheels stop immediately after turning slightly. Therefore, in a visible form, no trace of steering remains, and even the driver does not notice that rear wheel steering was performed for the purpose of estimating the friction coefficient of the road surface. Further, since the friction coefficient of the road surface is estimated, there is no danger that the stopped vehicle moves.

The friction coefficient of the road surface thus estimated is preferably corrected by the loaded weight of the vehicle. For this reason, the output of the vehicle height sensor 14 is referred to, and when the loaded weight exceeds a certain weight, the vehicle height is increased. The friction coefficient of the road surface may be corrected according to the output of the sensor 14.

When the friction coefficient of the road surface in the stopped state is detected, the traction control at the time of starting is started. That is, it is assumed that the driver operates the ignition key to start the engine, depresses the clutch, and puts the gear in the neutral state into the low gear or the second gear. At this time,
In step (201) of the main routine shown in FIG. 3, it is determined from the output of the gear position sensor 7 that the driver is about to start the vehicle. Then, in the following step (202), the moment of clutch meet is determined. The moment of the clutch meet is detected when the output of the rotary encoder provided on the driven shaft of the two shafts connected by the clutch is obtained, and the clutch meet sensor 1 including a pair of rotary encoders is detected.
When the output of 2 is obtained, "1" is set to the clutch meet flag in the timer interrupt routine described later,
It is determined from the clutch meet flag that the vehicle has started. When the presence or absence of the clutch meet is determined in step (202), the optimum engine output is determined using the friction coefficient of the road surface detected by the above-described estimation operation. The optimum engine output is determined from the friction coefficient of the road surface, the clutch position and speed and direction, the accelerator position and speed and direction, and the steering angle of the steering wheel according to a predetermined calculation formula or calculation table. Traction control is performed with the optimum engine output during the transition period from start to steady running.

In the traction control during the transition period, as a matter of course when the friction coefficient of the road surface is small, the control is performed so as to suppress the engine output. Further, when the accelerator angle when the driver depresses the accelerator is large, the vehicle is slippery, and therefore the traction control is performed in a direction to suppress the engine output. In addition, the closer the gear position is to a low gear such as a low gear, the larger the wheel rotation torque is. Also, if the clutch speed is high, the output torque of the engine is transmitted sensitively. When the steering angle is large, tire slip is likely to occur, and therefore control is performed in a direction in which the engine output is suppressed.

Regarding the clutch opening and the accelerator opening, the main routine is interrupted at fixed time intervals set by the timer, and is processed according to the start detection program defined in the interrupt routine shown in FIG. Is done. That is, after the clutch opening degree and the accelerator opening degree are acquired in steps (301) and (302) shown in FIG.
When the output of No. 2 is taken in and the clutch meet is performed, "1" is set in the clutch meet flag as shown in step (304). And in the main routine,
When the clutch meet flag is "1", it is possible to determine that clutch meet has been performed. Therefore, regardless of the length of the processing cycle of the main routine, detection and determination of clutch meet can be performed with a constant interrupt cycle. It is possible.

As described above, the traction control device 1
According to this, the friction coefficient of the road surface is detected before the vehicle is started, and the CPU 2 controls the engine output when the vehicle starts according to the detected friction coefficient of the road surface. Therefore, the vehicle is started from the stopped state. In this case, unlike a conventional traction control device, the road surface resistance on the verge of starting is unknown, so the vehicle is not left in an uncontrolled state at the moment when the vehicle starts. It is possible to realize stable traction control during the transitional transition period, which makes it possible to experience a comfortable riding comfort that is the same as when starting from normal running, without experiencing the discomfort caused by the wheels spinning. ..

Further, since the stopped wheels are steered until the direction is changed, and the friction coefficient of the road surface is estimated from the steering force required at that time, that is, the output of the electric motor 4, it is possible to estimate the friction coefficient of the road surface immediately before starting. By accurately grasping the friction coefficient and making traction control in the transitional period more reliable, it is possible to use a system that steers the rear wheels such as a four-wheel steering system from the force required for steering while stopped. By detecting the resistance of the road surface, it is possible to detect the friction coefficient of the road surface in advance without actually moving the vehicle, which makes it possible to estimate within a very short time until the driver gets into the vehicle and actually starts the vehicle. By using the determined friction coefficient of the road surface, highly accurate traction control can be realized in the transition period from start to steady running.

In the above embodiment, the four-wheel steering system is used to estimate the friction coefficient of the road surface in the stopped state. However, if the vehicle steers the front wheels by the power steering mechanism, the vehicle is in the stopped state. Steer the front wheels,
The friction coefficient of the road surface can be estimated from the road surface resistance at that time.

[0020]

As described above, the present invention detects the friction coefficient of the road surface before starting the vehicle, and controls the engine output when the vehicle starts according to the detected friction coefficient of the road surface. Therefore, when the vehicle is started from the stopped state, it is not left in an uncontrolled state at the moment when the vehicle starts, unlike the conventional traction control device, and therefore the start shifts to the steady running. It is possible to realize stable traction control in the transitional period, and to experience a comfortable riding comfort that is the same as when starting from normal running and without experiencing the discomfort caused by the wheels spinning. Produce an effect.

Further, according to the present invention, since the stopped wheel is steered until the direction is changed, and the friction coefficient of the road surface is estimated from the steering force required at that time, the friction coefficient of the road surface immediately before starting the vehicle. Can be accurately grasped and traction control in the transitional period can be made more reliable. For example, a system for steering the rear wheels like a four-wheel steering system, or a front wheel for boosting the power steering device. By using the system, the resistance of the road surface can be detected from the force required for steering while the vehicle is stopped, and the friction coefficient of the road surface can be detected in advance without actually moving the vehicle.
As a result, by using the friction coefficient of the road surface estimated within a very short time until the driver gets into the vehicle and actually starts, it is possible to realize accurate and reliable traction control during the transition period from start to steady running. There is an effect such as being able to.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of a traction control device of the present invention.

FIG. 2 is a flow chart for explaining a road surface friction coefficient estimating operation by a CPU shown in FIG.

FIG. 3 is a flowchart for explaining a traction control operation at the time of starting by the CPU shown in FIG.

FIG. 4 is a flowchart for explaining a start detection operation by the CPU shown in FIG.

[Explanation of symbols]

1 Traction control device 2 Friction coefficient estimation means, friction coefficient detection means, engine output control means (CPU) 4 Steering means (electric motor)

Claims (2)

[Claims] 1. A traction control device for preventing idling of a wheel by automatically controlling an engine output within a range of a driving force that the wheel can transmit to a road surface. A friction detecting a friction coefficient of a road surface before starting a vehicle. According to the coefficient detecting means and the friction coefficient of the road surface detected by this friction coefficient detecting means,
An engine output control means for controlling an engine output when the vehicle starts moving. 2. The friction coefficient detecting means includes a steering means for steering a stopped wheel until the direction changes and a friction coefficient estimating means for estimating a friction coefficient of a road surface from a steering force required by the steering means. The traction control device according to claim 1, further comprising: