JP2000211491A - Brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately control the braking force by providing a control starting means to start the control of the braking force based on the braking force detected by a braking force detecting means and the braking operation detected by a brake operation detecting means. SOLUTION: When a driver steps in a brake pedal, and the brake control is started, each detected value of a vehicle speed sensor 3, a vertical force detection sensor 4, a longitudinal force detection sensor 5 and a master cylinder hydraulic pressure sensor 6 is read. The braking force of a vehicle at the present point of time is operated. An ABS control condition is determined based on the braking force of a vehicle and a brake operating condition by the driver. For example, the temporal change of the braking force and the master pressure to be detected by the master cylinder hydraulic pressure sensor 6 is detected, and the ABS control condition is determined to be that the braking force is decreased after it is once increased. On the other band, the ABS control is not started irrespective of the increase/decrease in the braking force when the master pressure is decreased. The braking force can be appropriately controlled, and a large braking force can be obtained.

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 controlling a braking force during vehicle braking.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 9-2240, an ABS (anti-lock brake system) is used as a brake control device using road surface frictional force and brake torque without using wheel speed or the like. Systems that perform control are known. This control device determines the brake depressurization start timing of the ABS, that is, the timing of μMAX (maximum road friction coefficient) and the timing just before μMAX based on the time change (time differential value) of the road friction force and the brake torque. is there.

[0003]

However, the above-mentioned conventional brake control device has a problem that proper anti-lock brake control cannot be performed. For example, a conventional control device detects temporal changes in road surface frictional force, brake torque, and the like based on an output value of a stress sensor at the time of a brake operation, and determines a pressure reduction start timing of the brake pressure based on those change peaks. ing. When pressure reduction is started in this manner, when the driver depresses the brake pedal, the output of the stress sensor generates a peak point, and braking force control may be performed based on the peak point. In this case, proper braking force control cannot be performed.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a brake control device capable of performing appropriate braking force control.

[0005]

That is, a brake control device according to the present invention is a brake control device for controlling a braking force of a vehicle by adjusting a braking oil pressure applied to a wheel cylinder of a wheel during braking of the vehicle. Braking force detecting means for detecting power, brake operation detecting means for detecting a driver's brake operation, and a braking force detected by the braking force detecting means and a brake operation state detected by the brake operation detecting means. Control start means for starting the braking force control.

Further, in the brake control device according to the present invention, the braking force detecting means includes a braking force of the vehicle based on a longitudinal force applied to the traveling direction of the vehicle and a vertical force applied to the vertical direction of the vehicle. Is detected.

According to these inventions, since the braking force control is started in consideration of the driver's braking operation, it is possible to prevent the braking force control from being started when the driver steps on the brake. For this reason, it can be prevented that the braking force is controlled to be small by the braking force control, and a large braking force can be obtained by the braking force control.

[0008]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. (First Embodiment) FIG. 1 shows a configuration of a brake control device according to the present embodiment. As shown in FIG. 1, the brake control device 1 includes an ECU 2. The ECU 2 uses the CP
The computer mainly includes a U, a ROM, and a RAM. Various control routines including a brake control routine are stored in the ROM.

The input side of the ECU 2 is connected to a vehicle speed sensor 3, a vertical force detection sensor 4, a longitudinal force detection sensor 5, and a master cylinder hydraulic pressure sensor 6 provided for each wheel. The vehicle speed sensor 3 detects the traveling speed of the vehicle, and for example, a wheel speed sensor or the like is used. The vertical force detection sensor 4 detects a vertical force applied in the vertical direction of the vehicle, and includes, for example, a G sensor, an air pressure sensor of an air suspension pen, and a stroke sensor of a suspension. The load of the vehicle during control is estimated based on the output of the vertical force detection sensor 4.

The longitudinal force detecting sensor 5 detects a longitudinal force applied in the longitudinal direction of the vehicle, and includes, for example, a G sensor and a brake pad strain sensor. The master cylinder hydraulic pressure sensor 6 detects a hydraulic pressure generated in the master cylinder, and functions as a driver's brake operation detecting means. When the vehicle is provided with two brake systems, the master cylinder hydraulic pressure sensor 6 does not need to be provided for each of them, and may be provided for only one of them.

On the other hand, a brake actuator 7 is connected to the output side of the ECU 2 for each brake system. Each brake actuator 7 includes two holding valves 9 and two pressure reducing valves 10. Among them, two holding valves 9 and two pressure reducing valves 10 are brake hydraulic pressure control valve devices 11 in the sense of controlling the hydraulic pressure of the wheel cylinder.
Is configured.

The output side of the ECU 2 is connected to a pump motor 12 for driving a pump. By driving the pump motor 12, the pressure in the wheel cylinder is reduced. The brake systems that are subject to brake control are:
For example, a brake system is divided into two systems using a tandem type master cylinder.

FIG. 2 shows an example of a brake system to be subjected to brake control.

As shown in FIG. 2, the depression force of a brake pedal 24 is transmitted to a master cylinder 20 via a booster 22. The main passage 40 of the first brake system for the left front wheel FL and the right rear wheel RR is connected to one of the two pressurizing chambers provided in the master cylinder 20, and the right front wheel FR is connected to the other pressurizing chamber. The main passage 41 of the second brake system for the left rear wheel RL is connected. That is, in the brake system, the output passage from the master cylinder 20 is constituted by two diagonal passage systems. Since these brake systems have a common configuration, only the first brake system will be representatively described below, and the description of the second brake system will be omitted.

In the first brake system, the master cylinder 20 is divided into a wheel cylinder 50 for operating the brake 42 of the left front wheel FL and a wheel cylinder 50 for operating the brake 44 of the right rear wheel RR through the main passage 40, respectively. It is connected. The main passage 40 is connected to the master cylinder 2
After extending from 0, it branches into a forked shape, and one of the branch passages becomes a main passage 54, and the main passage 54 also branches into a forked shape and continues to two branched passages 56. The wheel cylinder 5 is located downstream of each branch passage 56.
0 and 50 are connected. The master cylinder hydraulic pressure sensor 6 is connected downstream of the other branch passage of the main passage 40.

In the middle of each branch passage 56, a holding valve 60, which is an electromagnetic normally-open valve, is provided. The holding valve 60 allows a bidirectional flow of the brake fluid between the master cylinder 20 and the wheel cylinder 50 when the solenoid is off, that is, when the solenoid is open, and blocks the flow when the solenoid is on, that is, when the solenoid is closed. Each branch passage 56 is provided with a check valve 64 that bypasses each holding valve 60. A proportioning valve 65 is provided in the middle of the two branch passages 56 corresponding to the right rear wheel RR.

Each reservoir passage 66 extends from a portion of each branch passage 56 between the holding valve 60 and the wheel cylinder 50, and reaches a reservoir 72. In the middle of each reservoir passage 66, a pressure reducing valve 70, which is an electromagnetic type normally closed valve, is provided. The pressure reducing valve 70 is in an off state of the solenoid,
That is, the flow of the brake fluid from the wheel cylinder 50 to the reservoir 72 is blocked in the closed state, and the flow is allowed in the on state, that is, the open state.

The reservoir 72 includes a reservoir housing 73
And a reservoir piston 74 is fitted in an airtight and slidable manner, and the reservoir chamber 7 formed by the fitting is formed.
The brake fluid is stored in 6. The reservoir piston 74 is
The spring 78 as an elastic member allows the reservoir chamber 76
Is constantly biased in a direction to decrease the volume.

A pump 82 is provided between the upstream side of the holding valve 60 of each branch passage 56 and the reservoir 72.
The pump 82 operates by driving the pump motor 12,
The brake fluid on the wheel cylinder 50 side is discharged to reduce the fluid pressure of the wheel cylinder. A check valve 8 for regulating the flow of the brake fluid is provided upstream and downstream of the pump 82.
4, 86 are provided.

Next, the operation of the brake control device will be described.

FIG. 3 shows a flowchart of the operation of the brake control device. In FIG. 3, the brake control process is started when the driver depresses the brake pedal 24. First, in step S10 (hereinafter, simply referred to as "S10"; the same applies to other steps). Vehicle speed V detected by 3 and vertical force detection sensor 4
, The longitudinal force Fx detected by the longitudinal force detection sensor 5 and the master pressure Pmc detected by the master cylinder fluid pressure sensor 6 are read.

Then, in S12, a calculation of the braking force Fb of the vehicle at the present time is performed. That is, the braking force Fb is
It is calculated by the following equation (1) based on the vertical force Fz and the longitudinal force Fx applied to the vehicle. In equation (1), K is a constant.

Fb = K ・ (Fx / Fz) ‥‥ (1) Next, in S14, it is determined whether the ABS control start condition is satisfied. The ABS control start condition is determined based on the braking force of the vehicle and the brake operation status of the driver, and is determined based on, for example, the braking force Fb and the master pressure Pmc.

More specifically, a temporal change in the braking force Fb and the master pressure Pmc is detected, and when the master pressure Pmc continues to increase, the fact that the braking force Fb decreases after the braking force Fb increases is considered as an ABS control start condition. And

As shown in FIG. 4, the horizontal axis represents the brake input,
Assuming that the braking force acting on the vehicle is on the vertical axis, the braking force also increases as the brake input continues to increase, but at some point the braking force peaks and then decreases. This is due to the fact that the tires are locked due to the increase in the brake input, and the road surface friction coefficient μ decreases. For this reason, the brake control, that is, the master pressure Pmc continues to increase, and the fact that the braking force Fb has decreased after the increase has been set as the ABS control start condition. By setting the start conditions in this manner, a large braking force can be obtained.

On the other hand, when the master pressure Pmc decreases, the ABS control is not started regardless of the increase or decrease of the braking force Fb. For example, as shown in FIG. 5, when the brake input is reduced due to the driver releasing the brake pedal, the ABS control is not started. In this case, looking at the temporal change of the braking force Fb, the value of the braking force Fb increases and then decreases, and a peak point appears in the apparent value of the braking force. However, since the brake input has not been increasing, the ABS control is not started.

When it is determined in S14 of FIG. 3 that the conditions for starting the ABS control are not satisfied, the process is terminated. On the other hand, when it is determined in S14 that the ABS control start condition is satisfied, the process proceeds to S16.

At S16, an ABS control process is performed.
In the ABS control process, for example, a drive signal is output from the ECU 2 to the brake control valve device 11 and the pump motor 12, respectively, and the holding valve 9, the pressure reducing valve 10, and the pump motor 12 are output.
Is appropriately operated, and the brake pressure of the wheel cylinder is controlled such that the value of the braking force Fb is near the peak point. The ABS control process may be a process of comparing the wheel speed with the estimated vehicle speed and controlling the brake pressure so that the braking force is appropriately obtained.

As described above, according to the brake control device of the present embodiment, the ABS control start condition is determined based on the braking force of the vehicle and the brake operation status of the driver, so that the driver can depress the brake pedal. If you return it,
ABS control is not started, and appropriate brake control can be performed.

For example, as shown in FIG. 6, when only the temporal change of the braking force is detected to determine the conditions for starting the ABS control, when the driver depresses the brake pedal, the apparent value of the braking force becomes apparent. The upper peak point p1 is generated, and there is a possibility that the brake pressure of the wheel cylinder is controlled to match the braking force near the peak point p1. In this case, FIG.
The appropriate braking force as shown by the dashed peak point p2 cannot be obtained. On the other hand, according to the brake control device according to the present embodiment, AB
Since the start condition of the S control is set, the ABS control is not started even if an apparent peak point occurs in the value of the braking force. Is done. Therefore, appropriate braking force control can be performed, and the braking force is not controlled to be small, so that a large braking force can be reliably obtained.

In the brake control device according to the present embodiment, it is desirable that a decrease in the brake input be a condition for terminating the ABS control. In this case, since the braking force is given according to the driver's intention, it is possible to prevent the driver from feeling uncomfortable when the control is released.

[0032]

As described above, according to the present invention, since the braking force control is started in consideration of the driver's braking operation, the braking force control is started when the driver steps on the brake. Can be prevented. For this reason, it can be prevented that the braking force is controlled to be small by the braking force control, and a large braking force can be obtained by the braking force control.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a brake control device according to an embodiment.

FIG. 2 is an explanatory diagram of a brake system to be controlled by a brake control device according to an embodiment.

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

FIG. 4 is an operation explanatory diagram of the brake control device according to the embodiment;

FIG. 5 is an explanatory diagram of an operation of the brake control device according to the embodiment.

FIG. 6 is an explanatory diagram of a comparative example with respect to the brake control device according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Brake control device, 2 ... ECU, 4 ... Vertical force detection sensor, 5 ... Front / rear force detection sensor, 6 ... Master cylinder hydraulic pressure sensor, 9 ... Holding valve, 10 ... Pressure reducing valve, 50 ... Wheel cylinder.

Claims (2)

[Claims] 1. A brake control device for controlling a braking force of a vehicle by adjusting a braking oil pressure applied to a wheel cylinder of a wheel during braking of the vehicle, a braking force detecting means for detecting a braking force of the vehicle, and a brake of a driver. Brake operation detecting means for detecting an operation, and control starting means for starting braking force control based on the braking force detected by the braking force detecting means and the brake operation state detected by the brake operation detecting means. A brake control device comprising: 2. The braking force detecting means detects a braking force of the vehicle based on a longitudinal force applied to a traveling direction of the vehicle and a vertical force applied to a vertical direction of the vehicle. The brake control device according to claim 1, wherein: