JP3680918B2 - Vehicle traction control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a traction control device that suppresses idling of drive wheels of a vehicle.
[0002]
[Prior art]
2. Description of the Related Art A traction control device that performs control to suppress idling of drive wheels is known in order to ensure traveling stability during acceleration when starting a vehicle. A known traction control device, when detecting idling of a driving wheel, suppresses idling by reducing the engine output or applying a braking force to the idling driving wheel.
[0003]
In a so-called brake control type traction control device that applies braking force to the drive wheels, it is necessary to reduce wear of the brake pads and damage to the drive system due to frequent traction control.
[0004]
The technique disclosed in Japanese Patent Application Laid-Open No. 5-229414 prohibits traction control in a high and medium speed range where almost no traction control is required. It is described as reducing damage.
[0005]
[Problems to be solved by the invention]
However, in brake-type traction control, the engine driving force and braking force work in opposite directions with respect to the drive shaft, and torque is generated. Therefore, especially when the vehicle is close to a stop state such as when starting and the engine driving force is high When traction control is performed, higher torque is generated than when there is no traction control, and a lot of fatigue is accumulated in the drive system. And if fatigue accumulates more than the intensity capacity of a drive system, it will be damaged.
[0006]
Furthermore, in a vehicle in which steering wheels such as FF type and 4WD type are driven, the driving force is smoothly transmitted at a constant speed even when the steering angle becomes large and the tolerance angle between the driving shaft and the steering shaft becomes large. However, when brake type traction control is adopted for the drive steering wheel connected by such a constant velocity joint, a load on the constant velocity joint having a small strength capacity is large. In particular, when the steering angle is increased, the strength capacity of the constant velocity joint is reduced, and this problem becomes more remarkable.
[0007]
In view of the above problems, the present invention extends the life of a drive system by reducing the input to the drive system connected to the drive steering wheel and suppressing the accumulation of fatigue in a vehicle that drives the steered wheel. It is an object of the present invention to provide a vehicle traction control device that can perform the above-described operation.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problem, a traction control device for a vehicle according to the present invention includes an idling detection unit that detects idling of a driving wheel and an idling of the driving wheel by applying a braking force to the driving wheel that has detected idling. In a vehicle traction control device including a braking force control unit that performs control to suppress, the driving wheel includes a steerable driving wheel connected to the driving device via a constant velocity joint, and the braking force control unit includes: If the vehicle speed is less than or equal to a predetermined speed that is considered to be almost stopped and the drive wheel idling suppression control is performed on both of the steerable drive wheels, the braking force applied to the drive wheels is applied to the other It is characterized by being lowered compared to the case.
[0009]
In a vehicle having a brake type traction control device and having steerable wheels that can be driven, a braking force is applied to both of the drive steering wheels at a speed equal to or less than a predetermined speed at which the vehicle is considered to be almost stopped. When idling suppression (traction) control is being performed, the drive steering wheels are both close to the stop state, so the engine driving force and the braking force applied to the steering wheel are substantially balanced in the opposite direction, thereby driving the drive shaft. High torque is generated, and a large load is applied particularly to a constant velocity joint having a small strength capacity. According to the present invention, when there is a possibility that such high torque is generated, the rotational force is released by allowing idling by reducing the braking force applied to the drive wheels as compared to other cases. Torque can be suppressed. Accordingly, it is possible to reduce the accumulation of fatigue of the drive system such as the constant velocity joint due to the torque. Generally, the steerable drive wheel is the front wheel.
[0010]
The braking force control means controls the braking force applied to the driving wheel based on the slip state of the driving wheel, and the braking force is applied to both the driving steering wheel and the vehicle at a predetermined speed or less. When the traction control to be applied is performed, it is preferable to limit the braking force to be applied below the upper limit value of the braking force set according to the steering angle of the steerable drive wheel.
[0011]
This is preferable because traction control can be performed while reducing the accumulation of fatigue in the drive system.
[0012]
This braking force upper limit value is preferably set to be smaller as the steering angle of steerable drive wheels is larger.
[0013]
Since the strength capacity of the constant velocity joint decreases as the steering angle increases, accumulation of fatigue in the constant velocity joint can be reduced by setting the upper limit of the braking force applied during traction control as the steering angle increases.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram showing a main part of a vehicle equipped with a traction control device according to the present invention.
[0015]
This vehicle is an FF type vehicle using front wheels 1FR and 1FL which are steering wheels among four wheels as drive wheels. The vehicle drive system is configured by connecting an engine 5, a transmission 6, an output shaft 50, a gear 51, and a drive shaft 52. The drive shaft 52 and the front wheels 1FR and 1FL are connected to a constant velocity joint 53R. , 53L, respectively.
[0016]
On the other hand, the steering system is configured by connecting a steering wheel 8, a steering shaft 80, a gear 82, and a tie rod 83, and the tie rod 83 is connected to the front wheels 1FR and 1FL. A steering angle sensor 81 for detecting the steering angle is attached to the steering shaft 80. A power steering device may be further connected to the steering system.
[0017]
The brake system includes a brake pedal 2, a brake booster 20, a master cylinder 22, and an actuator 3, and hydraulic oil lines extending from the actuator 3 are provided on the wheels 1FR, 1FL, 1RR, and 1RL. The brake pad 32 is operated by being connected to the wheel cylinder 31. A stop lamp switch 21 for detecting the operation state of the brake is attached to the brake pedal 2, and a wheel speed sensor 33 for detecting the rotation state of the wheel is attached to each wheel 1FR, 1FL, 1RR, 1RL. ing.
[0018]
The outputs of the stop lamp switch 21, each wheel speed sensor 33, and the rudder angle sensor 81 are input to the TRC computer 4, which controls the operation of the actuator 3. The traction control device according to the present invention includes: It corresponds to braking force control means. The engine 5 and the transmission 6 are connected to a control engine computer 7. The TRC computer 4 and the engine computer 7 are connected to each other.
[0019]
Here, the basic operation of the vehicle during normal travel will be described. During normal travel, the driving force of the engine 5 is transmitted to the front wheels 1FR and 1FL which are driving wheels via the transmission 6, the output shaft 50, the gear 51, the driving shaft 52 and the constant velocity joints 53L and 53R.
[0020]
When the steering wheel 8 is operated, the steering force is transmitted to the tie rod 83 via the steering shaft 80 and the gear 82, and the front wheels 1FR and 1FL, which are the steering wheels, are steered in a desired direction to change the traveling direction of the vehicle. be able to.
[0021]
When the brake pedal 2 is depressed, the brake booster 20 increases the depression force and transmits it to the master cylinder 22, and hydraulic oil is sent to the actuator 3. Brake is performed by operating the brake pad 32 by transmitting hydraulic oil from the actuator 3 to the wheel / cylinder 31 provided on each wheel.
[0022]
Next, the operation of this traction control device will be described with reference to FIGS. FIG. 2 is a flowchart showing the traction control operation. Hereinafter, unless otherwise specified, the control operation is executed by an arithmetic processing unit (CPU) in the TRC computer 4.
[0023]
In step S1, it is determined whether to perform traction control by comparing the estimated vehicle speed with the wheel speed sensor 33 of each wheel. When the wheel speed is higher than the estimated vehicle speed by a predetermined threshold value or more, it is determined that the wheel is idling and it is necessary to perform traction control, and the process proceeds to step S2. On the other hand, if the difference between the estimated vehicle speed and the wheel speed is within a predetermined range, it is determined that it is not in the idling state and it is not necessary to perform the traction control, and the subsequent processing is skipped and the process ends.
[0024]
In step S2, it is determined whether or not the vehicle is in a stacked state. Specifically, the estimated vehicle speed is a threshold value, for example, V ₁ km / h or less, which is considered to be almost stopped, and the wheel speed of the wheel having the slower wheel speed among the rear wheels 1RR, 1RL is almost stopped as well. below V ₂ km / h considered, and the engine speed is determined to stack state when sufficiently higher than the idling speed, in which case, the process proceeds to step S3. Otherwise, the process proceeds to step S4.
[0025]
In step S3, the state of the front wheels 1FR and 1FL which are drive steering wheels is determined. If both front wheels 1FR and 1FL are in the braking state by the brake type traction control, the process proceeds to step S5. In other cases, that is, if at least one is not braked, the process proceeds to step S4. To do.
[0026]
When the process proceeds to step S4, since one of the front wheels 1FR and 1FL is rotating, an extremely large force is applied to the constant velocity joints 53R and 53L even when a braking force is applied by the brake type traction control. There is nothing. Therefore, the control hydraulic pressure to be supplied to the wheel cylinders 31FR and 31FL necessary for obtaining the braking force to be applied according to the slip ratios of the respective wheels 1FR and 1FL and generating the braking force on the brake pads 32FR and 32FL. Are set, and the required control hydraulic pressure is supplied from the actuator 3.
[0027]
When braking is applied to both the front wheels 1FR and 1FL that shift to step S5, if the braking force that should be applied according to the slip ratio is applied as it is, the constant velocity joints 53R and 53L are greatly increased by the engine driving force and this braking force. Torque may be generated. Therefore, first, the hydraulic pressure supplied to the wheel cylinders 31FR and 31FL is set as the control hydraulic pressure upper limit value Pmax so that the braking force that can suppress the torque within the allowable torque of the constant velocity joints 53R and 53L is generated in the brake pads 32FR and 32FL. To do. Since the allowable torque of the constant velocity joints 53R and 53L becomes smaller as the steering angle of the front wheels becomes larger, based on the detected value of the steering angle sensor 81, as shown in FIG. It is preferable to set.
[0028]
In step S6, as in step S4, the control hydraulic pressure required to generate the braking force to be applied according to the slip ratio is obtained and set as the estimated hydraulic pressure Pe.
[0029]
In step S7, the obtained Pmax and Pe are compared. When the estimated hydraulic pressure Pe is equal to or lower than the control hydraulic pressure upper limit value Pmax, the torque applied to the constant velocity joints 53R and 53L does not exceed the allowable torque even if the braking force is controlled according to the slip ratio, so that step S8 is shown. Then, the same traction control as that in step S4 is performed with the oil pressure supplied to the corresponding wheel cylinders 31FR and 31FL as Pe.
[0030]
On the other hand, when the estimated hydraulic pressure Pe is larger than the control hydraulic pressure upper limit value Pmax, the torque applied to the constant velocity joints 53R and 53L may exceed the allowable torque when the braking force is controlled according to the slip ratio. As described above, the hydraulic pressure supplied to the corresponding wheel cylinders 31FR and 31FL is set to Pmax or less to perform traction control by braking. That is, by performing traction control while allowing slipping more than in step S4, the torque applied to the constant velocity joints 53R and 53L is suppressed within the allowable torque, and traction control is performed.
[0031]
Furthermore, since a strong braking force is not applied, the jerky feeling and the feeling of jumping out of the vehicle when the tire grip is restored can be suppressed. The larger the steering angle, the smaller the braking force. In the middle and small steering angle regions, the braking force necessary for slip reduction is secured to ensure running performance, while in the large steering angle region, constant velocity joints, etc. The service life can be extended.
[0032]
After the traction control, in any case, the process proceeds to step S10, and it is determined whether or not the traction control should be terminated by examining whether or not the idling of the vehicle is suppressed. If it is necessary to continue the traction control, the process returns to step S2, and the traction control is continued. If there is no need, the process is terminated.
[0033]
In the above description, the FF type vehicle has been described as an example. However, the traction control device of the present invention is also applicable to traction control on the front wheel side in a 4WD type vehicle.
[0034]
【The invention's effect】
As described above, according to the present invention, in a vehicle that performs brake-type traction control, when the traction control is performed on both of the drive steering wheels at a speed equal to or lower than a predetermined speed at which the vehicle is considered to be almost stopped, By restricting the braking force applied to these drive steering wheels, the strong braking force can be suppressed, the life of the drive system such as a constant velocity joint can be extended, and the jerky feeling and the feeling of popping out when the grip is recovered can be suppressed.
[0035]
Furthermore, by reducing the braking force applied at the time of traction control as the steering angle increases, the above-described drive system ( It is possible to extend the life of constant velocity joints).
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a main part of a vehicle equipped with a vehicle traction control device according to the present invention.
FIG. 2 is a flowchart showing a control operation of the vehicle traction control apparatus according to the present invention.
FIG. 3 is a graph showing a relationship between a steering angle and a control hydraulic pressure upper limit value in the vehicle traction control device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Wheel, 2 ... Brake pedal, 3 ... Actuator, 4 ... TRC computer, 5 ... Engine, 6 ... Transmission, 7 ... Engine computer, 8 ... Steering wheel, 21 ... Stop lamp switch, 31 ... Wheel and cylinder, 32 ... Brake pads, 33... Wheel speed sensor, 53... Constant velocity joint, 81.

Claims (5)

In a vehicle traction control device comprising: an idling detection unit that detects idling of a driving wheel; and a braking force control unit that performs control for suppressing idling of the driving wheel by applying a braking force to the driving wheel that has detected idling. ,
The drive wheel includes a steerable drive wheel connected to a drive device via a constant velocity joint, and the braking force control means is configured such that the vehicle speed is equal to or lower than a predetermined speed that is considered to be almost stopped , and the steering is performed. The vehicle traction is characterized in that the braking force applied to the driving wheel is reduced when the idling suppression control of the driving wheel is performed for both of the possible driving wheels. Control device.   2. The vehicle traction control device according to claim 1, wherein the steerable drive wheel is a front wheel. 3. The braking force control unit according to claim 1, wherein the braking force control unit reduces the braking force applied when the vehicle speed is equal to or lower than the predetermined speed and the engine speed is sufficiently higher than the idle speed. The vehicle traction control device according to claim 1. Said braking force control means is for controlling the braking force applied to the drive wheel based on the slip state of the drive wheels, vehicle speed is less than the predetermined speed, and the wheels of the steerable drive wheel On the other hand, when the idling suppression control of the drive wheel is performed, the braking force to be applied below the braking force upper limit value set according to the steering angle of the steerable drive wheel is limited. The traction control device for a vehicle according to any one of claims 1 to 3 . 5. The vehicle traction control device according to claim 4, wherein the braking force upper limit value is set to be smaller as the steering angle of the steerable drive wheel is larger.

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