JP3607990B2 - 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, even at low speeds, for example, when the rotational inertia of the drive system is high, such as when the engine speed is high, the braking force required for traction control increases, which causes brake pad wear and the drive system. There is a risk of damage.
[0006]
In view of the above problems, an object of the present invention is to provide a vehicle traction control device that performs brake-type traction control that can effectively reduce brake pad wear and drive system damage even at low speeds.
[0007]
[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. A traction control device for a vehicle that includes a braking force control unit that performs suppression control further includes an inertial force detection unit that detects the magnitude of the rotational inertial force of the drive system, and the braking force control unit has a large rotational inertial force. In this case, the braking force applied to the drive wheels is reduced as compared with the case where the rotational inertia force is small.
[0008]
According to the present invention, when the rotational inertia force is large, the braking force applied to the idling drive wheel is reduced when the traction control is performed using the braking force as compared with other cases. Therefore, the wear of the brake pad can be suppressed as much as the braking force is reduced, and the torsional torque applied to the drive system by reducing the braking force can be suppressed, thereby extending the life of the parts.
[0009]
Preferably, the detecting means detects the magnitude of the rotational inertia force based on the engine speed, or detects the magnitude of the rotational inertia force by detecting a reduction ratio.
[0010]
For the same reduction ratio, the rotational inertia force of the drive system increases as the engine speed increases. In addition, if the engine speed is the same, the rotational inertia force of the drive system as viewed from the end side increases as the speed reduction ratio increases. For this reason, when the engine speed is high or the reduction ratio is large, it is preferable to reduce the braking force applied during traction control by assuming that the rotational inertial force of the drive system is large. Of course, you may use combining both.
[0011]
The braking force control means controls the braking force applied to the drive wheel based on the slip state of the drive wheel, and is applied to a braking force upper limit value or less set according to the magnitude of the rotational inertia force. It is preferable to limit the power.
[0012]
During traction control, the braking force is controlled based on the slip state of the drive wheel, and the braking force applied by the braking force control means is kept below the braking force upper limit value set according to the magnitude of the rotational inertia force. Thus, effective traction control can be performed without increasing the braking force more than necessary.
[0013]
The braking force upper limit value is preferably set smaller as the engine speed is higher or as the reduction ratio is larger.
[0014]
If it does in this way, effective traction control can be performed according to an engine speed and a reduction gear ratio.
[0015]
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.
[0016]
This vehicle is a 4WD type vehicle having all four wheels 1FR, 1FL, 1RR, and 1RL as driving wheels. The vehicle drive system includes an engine 5 and a transmission 6, and the transmission 6 and the wheels 1FR, 1FL, 1RR, 1RL are connected to each other via a drive shaft, a differential gear, and the like (not shown). Yes.
[0017]
In this vehicle braking system, a brake pedal 2, a brake booster 20, a master cylinder 22 and an actuator 3 are connected, 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 and the wheel speed sensors 33 are input to the TRC computer 4. The TRC computer 4 controls the operation of the actuator 3 and corresponds to the braking force control means of the traction control device according to the present invention. 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]
Normally, when the brake pedal 2 is depressed during traveling, 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.
[0020]
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.
[0021]
In step S1, a slipping wheel is detected by comparing the vehicle speed with the wheel speed sensors 31FR, 31FL, 31RR, and 31RL. In step S2, a mode for determining whether to increase, hold, or reduce the hydraulic pressure supplied to the wheel cylinder 31 of the slipping wheel is determined, and a control command to the actuator 3 to achieve each mode is determined. (Any pressure increase, hold, pressure reduction command) is determined. Next, in step S3, the wheel cylinder pressure of each wheel is estimated by calculation based on the last final control command determined in each of steps S6, S9, S11, and S12 described later.
[0022]
When brake type traction control is performed in accordance with the slip state when the rotational inertia force of the drive system is large, a large force is applied to the drive system, which may damage the drive system. As a case where the rotational inertia force of such a drive system is large, there is a case where the reduction ratio is large when the engine speed is high. Therefore, in step S4, the rotational speed information of the engine 5 and the gear position in the transmission 6 or the information on the reduction ratio are received from the engine computer 7, and the upper limit value of the hydraulic pressure supplied to the wheel cylinder 31 according to the engine rotational speed and the gear position. The oil pressure limit value is calculated. The engine computer 7 functions as a means for detecting the rotational inertia force.
[0023]
FIG. 3 is a graph showing an example of the relationship among the limited hydraulic pressure value, the engine speed, and the gear position set in this way. L1, L2, and L3 in the figure indicate the relationship between the engine speed and the limit hydraulic pressure value when the sub-transmission is in the L range and the main transmission is 1st, 2nd, and 3rd, respectively.
[0024]
As shown in FIG. 3, the limit hydraulic pressure value is set to be smaller as the engine speed is higher when the gear position is the same, that is, when the reduction ratio is constant. If the engine speed is the same, the lower the gear position, that is, the smaller the reduction ratio, the smaller the gear position is set.
[0025]
For example, in the case of the first speed in the L range, the limit hydraulic pressure value is set to 0 when the engine speed is equal to or higher than a predetermined N (rpm). This corresponds to a state where braking is not performed.
[0026]
In step S5, it is determined whether or not the limit hydraulic pressure of the wheel cylinder 31 calculated in step S3 is equal to or less than the estimated hydraulic pressure calculated in step S4.
[0027]
When a negative determination is made in step S5, that is, when the estimated hydraulic pressure exceeds the limit hydraulic pressure, the process proceeds to step S6, and the control command determined in step S2 is set as the final control command.
[0028]
If the determination in step S5 is affirmative, that is, if the estimated oil pressure is equal to or lower than the limit oil pressure, the process proceeds to step S7, and further, it is determined whether or not the estimated oil pressure is equal to the limit oil pressure. If an affirmative determination is made in step S7, the process proceeds to step S8, and if a negative determination is made, the process proceeds to step S10.
[0029]
In step S8, it is determined whether or not the control command determined in step S2 is a pressure increase command. If the determination in step S8 is affirmative, the process proceeds to step S9, and the final control command is set as a holding command. On the other hand, if a negative determination is made in step S8, the process proceeds to step S6, and the control command determined in step S2 is set as the final control command.
[0030]
In step S10, it is determined whether or not the control command determined in step S2 is a pressure reduction command. If an affirmative determination is made in step S10, the process proceeds to step S11, and the control command determined in step S2 is set as a final calculation command. If a negative determination is made in step S10, the process proceeds to step S12, and the final control command is set as a pressure reduction command.
[0031]
In step S13, the actuator 3 is controlled according to the final control command determined in steps S6, S9, S11, and S12. Specifically, if the final control command is a pressure-increasing command, slip is detected if the final control command is a holding command so that the hydraulic pressure of the wheel cylinder 31 of the wheel in which the slip is detected is increased. The actuator 3 is controlled so that the hydraulic pressure of the wheel cylinder 31 of the wheel being held is maintained, and if the final control command is a pressure reduction command, the hydraulic pressure of the wheel cylinder 31 of the wheel where the slip is detected is reduced. Thus, the operating oil pressure is controlled so as not to exceed the limit oil pressure, and the braking state of each wheel is controlled.
[0032]
By performing such traction control, the braking force applied in the traction control of each wheel is adjusted to be lower than the limit value calculated in advance from the engine speed and the gear position. For this reason, the input torque to the drive system due to the braking force in a region where the rotational inertia force of the drive system is large is suppressed, and the damage resistance of the drive system can be ensured particularly in the low speed region.
[0033]
In addition, since the hydraulic pressure limit is set in a region where the engine speed is high and a region where the reduction ratio is large, the traction control performance in the low speed region is not impaired, and the running performance is ensured.
[0034]
In the above description, the 4WD vehicle has been described, but the present invention can also be suitably applied to two-wheel drive vehicles such as FF and FR. In this embodiment, the control is performed by estimating the hydraulic pressure of the wheel cylinder. However, a pressure sensor for detecting the hydraulic pressure of the wheel cylinder may be provided, and the control may be performed based on the output of this sensor.
[0035]
【The invention's effect】
As described above, according to the present invention, the braking force applied at the time of traction control is limited in a region where the rotational inertia of the drive system is large, such as a region where the engine speed is high or a region where the reduction ratio is large. The input torque to the system can be suppressed, and damage to the drive system can be effectively prevented.
[0036]
Furthermore, by setting the upper limit value of the braking force according to the engine speed and the reduction ratio, the traction control is effectively functioned when the engine is running at a low speed or when the reduction ratio is small, and the drive system is protected. Can do.
[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 among an engine speed, a gear position, and a control oil pressure 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, 21 ... Stop lamp switch, 31 ... Wheel cylinder, 32 ... Brake pad, 33 ... Wheel Speed sensor.

Claims (6)

In a traction control device for a vehicle, comprising: an idling detection unit that detects idling of a driving wheel; and a braking force control unit that performs control to suppress idling of the driving wheel by applying a braking force to the driving wheel that has detected idling. ,
It further comprises detection means for detecting the magnitude of the rotational inertial force of the drive system,
The vehicular traction characterized in that the braking force control means is configured to reduce the braking force applied to the drive wheels when the rotational inertial force is large compared to when the rotational inertial force is small. Control device. 2. The vehicle traction control device according to claim 1, wherein the detecting means detects the magnitude of the rotational inertia force based on an engine speed. 2. The vehicle traction control device according to claim 1, wherein the detecting means detects the magnitude of the rotational inertia force by detecting a reduction ratio. The braking force control means controls the braking force applied to the drive wheel based on the slip state of the drive wheel, and the braking force upper limit value set according to the magnitude of the rotational inertia force The traction control device for a vehicle according to any one of claims 1 to 3, wherein a braking force applied to the following is limited. 5. The vehicle traction control device according to claim 4, wherein the braking force upper limit value is set smaller as the engine speed is higher. 5. The vehicle traction control device according to claim 4, wherein the braking force upper limit value is set to be smaller as the speed reduction ratio is larger.

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