JP2000211486A - Brake control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the dangerous braking force keeping operation during the traveling by prohibiting the braking force keeping control by a braking force keeping means when a wheel lock is judged. SOLUTION: A braking force keeping part 6a makes use of the differential speed between the wheel speed and the pseudo vehicle body speed signal for each wheel, and judges the wheel lock if this differential speed is not less than the specified value, and continued for not less than the specified time. The braking force keeping product is prohibited including a case where the specified differential speed is generated between the actual vehicle body speed and the pseudo vehicle body speed, and the pseudo vehicle body speed is zero while the actual vehicle body speed is not zero yet. The wheel lock is judged when the pressure dropping time is not less than the specified value, and the wheel speed in that condition is zero by monitoring the pressure dropping time of a brake for each wheel by the braking force keeping part 6a while controlling the wheel lock prevention by an anti-lock control means 6b. Thus, the braking force keeping control is prohibited to prevent the wheel from being in a dangerous condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control device for a vehicle, and more particularly to a brake control device for a vehicle provided with a wheel stop state determination means necessary for performing brake control near a locked state of wheels.

[0002]

2. Description of the Related Art A conventional brake control device is disclosed in, for example, Japanese Patent Laid-Open No. 4-244462.
This device automatically holds the braking force when the vehicle stops. That is, when the vehicle is stopped, the braking electromagnetic check valve is controlled to maintain the braking force irrespective of the instruction from the brake pedal, and at the time of start, the clutch position is set in advance in the process of returning the clutch pedal by the driver. Canceled when passing the operation detection point. The judgment of vehicle stop is
For example, it is performed based on the output of a sensor that detects the rotational speed of the wheel. A state in which the vehicle is temporarily stopped by the braking force holding control of the brake control device (wheel lock state).
Is detected, the vehicle does not start moving even when the brake pedal is released on the slope, and the vehicle can start smoothly. In recent years, it has been proposed to combine such a brake control device with an anti-lock brake system.

[0003]

By the way, in such a brake control device, a signal from a wheel speed sensor provided for each wheel is used as basic data for judging a vehicle state. Speed is calculated. This pseudo vehicle speed is different from the actual vehicle speed.For example, even if the pseudo vehicle speed gradually decreases and becomes zero, the actual vehicle speed may not yet be zero. There is. Moreover, the braking force holding control determines that the vehicle has stopped, and automatically holds the braking force irrespective of the driver's intention, causing a problem that the vehicle is put into a dangerous state.

On the other hand, in an anti-lock brake system, a control limit may be reached on a braking road surface having an extremely low friction coefficient, and the wheels may be locked. In the case of a device in which the brake control device that holds the braking force and the antilock brake system are combined, the pseudo vehicle body speed becomes zero in the determination by the antilock brake system in the wheel lock state at such a braking limit. ing. In the brake control device, it is efficient to use the judgment of the anti-lock brake system, and even though the vehicle speed is not yet zero, the braking force is automatically determined regardless of the driver's intention. And the vehicle is put into a dangerous state.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem, and it is an object of the present invention to provide a vehicle brake control which can limit automatic braking force holding by a brake control device when a pseudo vehicle speed differs from an actual vehicle speed. It is intended to provide a device.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle brake provided with braking force holding means for holding a braking force by determining a vehicle stop state based on wheel speed signals from respective wheel speed sensors. The control device compares the speed difference between each wheel speed signal and the pseudo vehicle speed signal with the pseudo vehicle speed calculating means for calculating the pseudo vehicle speed signal based on the wheel speed signal from each wheel speed sensor. Wheel lock determining means for determining that the wheel is locked when a state in which the speed difference in the wheel speed signal is equal to or greater than a predetermined value has elapsed for a predetermined time or more. This is achieved by a vehicle brake control device that prohibits the braking force holding control by the power holding means.

According to this configuration, the wheel lock determination uses the speed difference between the wheel speed signal and the pseudo vehicle speed signal for each wheel, and this speed difference is equal to or more than a predetermined value and continues for a predetermined time or more. For example, it is determined that the wheel is locked, a predetermined speed difference occurs between the actual vehicle speed and the pseudo vehicle speed, and further, the pseudo vehicle speed is zero even though the actual vehicle speed is not yet zero. In addition, the braking force holding control can be prohibited to prevent the vehicle from falling into a dangerous state.

It is another object of the present invention to compare a wheel speed signal and a threshold value with braking force holding means for holding a braking force by determining a vehicle stop state based on a wheel speed signal from each wheel speed sensor. A vehicle brake control device having anti-lock control means for reducing or increasing the brake pressure by monitoring the pressure reduction time of each wheel brake during the wheel lock prevention control. A wheel lock determining unit that determines that the wheel is locked when the wheel speed becomes equal to or more than a predetermined value and the wheel speed becomes zero, and that when the wheel lock is determined by the wheel lock determining unit, the braking force is held by the braking force holding unit. This is achieved by a vehicle brake control device that prohibits control.

According to this structure, during the wheel lock prevention control by the anti-lock control means, the wheel lock determination means monitors the brake depressurization time for each wheel, and the depressurization time is equal to or more than a predetermined value and the state is determined. When the wheel speed of the wheel becomes zero, it is determined that the wheel is locked, the braking force holding control is prohibited, and the vehicle can be prevented from falling into a dangerous state.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a vehicle brake control device according to an embodiment of the present invention.
This vehicle brake control device 1 includes a master cylinder 3 with a brake switch, a braking force adjustment mechanism 4, a control unit 6, and a braking force supply mechanism 8, and is connected to the brake unit 5 of the wheels 7. You. The control unit 6 further includes various switches such as a clutch stroke sensor 2, a main switch 15, an ignition switch 16, an engine rotation sensor 17, a wheel speed sensor 18, a parking sensor 19, and a neutral switch 20 connected to the clutch pedal 10. And signals from various sensors. The control unit 6 controls the braking force adjustment mechanism 4 and the braking force supply mechanism 8 according to the connection state of these various switches and the output state of various sensors.

Here, the clutch stroke sensor 2 outputs a signal of a voltage value corresponding to the depression amount of the clutch pedal 10. The brake switch of master cylinder 3
This is for detecting whether or not the brake pedal 11 is depressed, and is turned on when depressed. The braking force adjustment mechanism 4 controls the flow of the brake oil to the brake unit 5, and controls the brake oil flowing through the hydraulic paths 4 a and 4 b in accordance with the depression of the brake pedal 11. Also,
When the braking force is maintained, the valve on the hydraulic path 4b is closed after the brake oil is supplied to the brake unit 5 according to a command from the control unit 6, so that the backflow does not occur. The braking force supply mechanism 8 includes an actuator or the like,
Regardless of the depression of the brake pedal 11, when the braking force holding unit provided in the control unit 6 determines that the holding of the braking force is necessary, the brake is applied to the wheels and the hydraulic pressure is continuously generated to further maintain the braking state. .

The control unit 6 includes a braking force holding unit 6a as the above-described braking force holding unit, and may further include an antilock control unit 6b as an antilock control unit. The braking force holding unit 6a processes the signals from the sensors to determine whether the vehicle is stopped. In particular, regarding the vehicle speed, the calculation of the pseudo vehicle speed based on the detection by the wheel speed sensor 18 is mainly performed, and the vehicle stop determination is performed. The calculation of the pseudo vehicle speed is, for example, a so-called “select high” commonly used, and basically selects the one with the highest wheel speed from each wheel. When it is determined that the vehicle is stopped, the braking force adjustment mechanism 4 and the braking force supply mechanism 8 are operated as described above, and the braking force is maintained by continuously applying the braking pressure. When the anti-lock control unit 6b is provided, the pseudo vehicle body speed calculated in the same manner as the braking force holding unit 6a is used, and the speed of each wheel based on each wheel speed sensor is used for the pseudo vehicle speed. And controlling the braking force of each wheel during braking.

Hereinafter, the operation of the device of the present invention will be described. FIG. 2 is a flowchart illustrating the operation of the vehicle brake control device according to the embodiment of the present invention. First, the process is started in step S101 in the traveling state based on the signals from the sensors. Then, in step S102, the braking force holding unit 6a determines whether the speed difference between the speed of any one of the wheels and the pseudo vehicle body speed is equal to or greater than a predetermined value.

In step S103, step S102
It is determined whether or not the speed difference continues for a predetermined time or more for a wheel whose speed difference is equal to or more than a predetermined value. If it is determined in step S103 and step S102 that the speed difference between the wheel speed and the pseudo vehicle speed exceeds a predetermined value for a predetermined time or more, there is a difference between the actual vehicle speed and the pseudo vehicle speed. Can be determined. Then, if it is determined in step S103 that the speed difference between the wheel speed and the pseudo vehicle speed is equal to or greater than a predetermined value and has continued for a predetermined time or more, step S103 is executed.
At 104, it is determined that this wheel is wheel locked,
Proceed to step S105. On the other hand, if it is determined in step S103 and step S102 that the speed difference is not equal to or greater than the predetermined value, or that the speed difference does not continue for a predetermined time even if the difference is equal to or greater than the predetermined value, the process proceeds to step S105.

In step S105, it is determined whether a wheel lock determination has been made. If the wheel lock determination has not been made, the process proceeds to step S106. If the wheel lock determination has been made, the process returns in step S107. In step S106, the braking force holding action is prohibited. As described above, a predetermined speed difference occurs between the actual vehicle speed and the pseudo vehicle speed, and further includes a case where the pseudo vehicle speed is zero even though the actual vehicle speed is not yet zero. Prohibit braking hold control. In this case, there is a possibility that the wheel is not locked, but if it is only the braking force holding control, there is no obstacle to running even if the holding control itself is prohibited, and avoid dangerous braking holding operation during running. Can be.

FIG. 3 is a flowchart showing the operation of the vehicle brake control device according to another embodiment of the present invention. In the present embodiment, a vehicle brake control device in a case where antilock brake control and braking force holding control are combined is shown. First, the process is started in step S201 at the time of the traveling state based on the signal from each sensor. Then, during the anti-lock brake control, the anti-lock control unit 6b determines in step S202 whether or not the speed difference between the speed of any one wheel and the pseudo vehicle body speed is equal to or more than a predetermined value (determination 1). At this time, if the speed difference is not equal to or larger than the predetermined value, the process proceeds to step S204, and if it is equal to or larger than the predetermined value, the process proceeds to step S203. Step S20
In 3, it is determined whether or not the time of the determination 1 is equal to or longer than a predetermined time (determination 2).

In step S202 (judgment 1) and step S203 (judgment 2), it is determined based on the signal from the wheel speed sensor 18 whether or not the actual wheel speeds recover to the pseudo vehicle body speed. It is indirectly determined whether a speed difference that causes a problem is created. Therefore, if the speed difference is equal to or more than the predetermined value and is maintained for the predetermined time in the determinations 1 and 2, it is determined that the actual wheel speed does not recover to the pseudo vehicle body speed, and a problematic speed difference is generated. The process proceeds to step S205 from the determination that there is. On the other hand, if the predetermined time has not been reached in step S203 (determination 2), the process proceeds to step S204.

In step S204, the wheel speed sensor 18
This is a further step when it is determined that each wheel speed is restored to the pseudo vehicle body speed based on the signal from the vehicle, and the decompression time by the antilock brake control in the antilock control unit 6b is a predetermined time for any one of the wheels. It is determined whether the above is true (determination 3). This step S
At 204, it is determined whether or not each wheel speed is restored to the pseudo vehicle speed based on the decompression time by the antilock brake control. Then, it is determined that the actual wheel speed does not recover to the pseudo vehicle body speed, and the process proceeds to step S205 because a problem has occurred. On the other hand, if the decompression time falls within the predetermined time, the process proceeds to step S207.

In step S205, the above determinations 1, 2, 2
For the wheels for which it is determined that the actual wheel speed does not recover to the pseudo vehicle body speed in 3, it is determined from the signal from the wheel speed sensor 18 whether the wheel speed is 0 Km / h (determination 4). At this time, if the wheel speed of this wheel is 0 Km / h, the pseudo vehicle body speed indicates a certain speed from the above determination 1 or determination 3, so that this wheel is notwithstanding the anti-lock brake control, Is in the locked state, which is considered to be the anti-lock brake control limit, and
At 06, it is determined that the wheels are locked. On the other hand, if the wheel speed of the wheel is not 0 km / h, the process proceeds to step S207. As described above, the antilock brake control limit is detected in determinations 1 to 4.

Next, a vehicle stop determination for performing the braking force holding control by the braking force holding unit 6a is performed. Therefore, in step S207, the speed of all the wheels is determined (determination 5). That is, judgment 1 to judgment 4 for each wheel
Will be integrated again. If the wheel speeds of all the wheels are 0 Km / h, the process proceeds to step S208,
If the speed is not 0 km / h, the vehicle is in a running state, and therefore, step S
Proceed to 210 and return.

In step S208, it is determined whether all the wheels have been determined to be wheel locked in step S206 (determination 6). If it is determined that all the wheels are locked, a completely locked state is established and the vehicle is in a running state, so the process proceeds to step S210 and returns. Here, the pseudo vehicle speed is based on the signal from the wheel speed sensor 18. However, the vehicle speed gradually decreases from the moment when the wheel speeds of all the wheels become 0 km / h, so that the vehicle runs as a vehicle. It is in a state. On the other hand, when there is a wheel that has not passed through step S206, it is not determined that all the wheels are in the wheel lock state.
Proceed to step S209. Then, this step S20
In step S207, the wheel speeds of all the wheels are 0 km in step S207.
/ H, it is determined that the vehicle is stopped, and the valve V
Is closed to enter the braking force holding control. As described above, in this embodiment, it is possible to determine the wheel lock in the vicinity of the anti-lock brake control limit, and it is possible to avoid a dangerous operation of holding the brake during traveling.

[0022]

As described above, according to the vehicle brake control device of the present invention, the speed difference between the wheel speed signal and the pseudo vehicle speed signal for each wheel is equal to or more than a predetermined value and continues for a predetermined time or more. Then, a predetermined speed difference occurs between the actual vehicle speed and the pseudo vehicle speed, and further, including the case where the pseudo vehicle speed is zero even though the actual vehicle speed is not yet zero, Prohibit braking hold control. Therefore, dangerous braking operation during traveling can be avoided. Also, based on the wheel speed signal for each wheel, it is determined whether or not the actual wheel speed has recovered to the pseudo vehicle speed, and based on the decompression time by the antilock brake control, each wheel speed has reached the pseudo vehicle speed. By determining whether or not to recover, it is possible to determine wheel lock in the vicinity of the anti-lock brake control limit, and it is possible to avoid dangerous braking operation during traveling.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a vehicle brake control device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the vehicle brake control device according to the embodiment of the present invention.

FIG. 3 is a flowchart illustrating an operation of a vehicle brake control device according to another embodiment of the present invention.

[Description of Signs] 1 Vehicle brake control device 2 Clutch stroke sensor 3 Brake switch 4 Braking force holding means 5 Memory 6 Control unit 10 Clutch pedal 18 Wheel speed sensor

Claims (2)

[Claims] 1. A vehicle brake control device comprising a braking force holding means for holding a braking force by determining a vehicle stop state based on a wheel speed signal from each wheel speed sensor. A pseudo vehicle speed calculating means for calculating a pseudo vehicle speed signal based on the speed signal, and comparing a speed difference between each wheel speed signal and the pseudo vehicle speed signal, wherein the speed difference in one of the wheel speed signals is equal to or greater than a predetermined value. Wheel lock determining means for determining that the wheel is locked when the state of あ る is longer than a predetermined time, and prohibiting the braking force holding control by the braking force holding means when the wheel lock determination is made by the wheel lock determining means. A brake control device for a vehicle, comprising: 2. A braking force holding means for holding a braking force by determining a vehicle stop state based on a wheel speed signal from each wheel speed sensor, and reducing the brake pressure by comparing the wheel speed signal with a threshold value. Or, in a vehicle brake control device provided with anti-lock control means for performing pressurization control, during the wheel lock prevention control, monitor the decompression time of the brake of each wheel, the decompression time of one of the wheels becomes a predetermined value or more,
And a wheel lock determining means for determining that the wheel is locked when the wheel speed becomes zero, and prohibiting the braking force holding control by the braking force holding means when the wheel lock is determined by the wheel lock determining means. A vehicle brake control device characterized by the above-mentioned.