JP2000168521A - Brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake control device to permit the driver to certainly perform manipulation of the vehicle behavior even under automatic braking without giving an incompatible feeling to the driver even if automatic braking is conducted in case the vehicle is to be braked automatically. SOLUTION: A brake control device is equipped with running condition sensing means 7-12 to sense the running condition of a vehicle, a brake request preparing means 1 to judge whether the vehicle requires a brake application on the basis of the obtained vehicle running condition and prepares a brake request if braking application is judged as necessary, and brake control means 1-6 to receive a braking command prepared by the means 1 and apply brakes to the vehicle with a deceleration and deceleration incremental gradient below their maximum values at which the driver can make manipulation of vehicle behavior.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a brake control device for braking a vehicle.

[0002]

2. Description of the Related Art As a brake control device for braking a vehicle, there is known a brake control device described in Japanese Patent Application Laid-Open No. Hei 6-312655. The control device described in JP-A-6-312655, by an electronic control unit (ECU), determines the vehicle state from various sensor outputs to determine whether or not braking is necessary. The deceleration is calculated, and the vehicle is automatically braked according to the target deceleration.

[0003]

In the control device as described above, since the ECU performs automatic braking according to the vehicle state, the vehicle may be braked when the driver does not expect it. In this case, it is conceivable that the driver may feel uncomfortable, or when the automatic braking generates a large braking force, there is no room for the driver to operate the vehicle behavior by the automatic braking.

Accordingly, an object of the present invention is to provide an automatic braking system that does not cause a driver to feel uncomfortable even if the automatic braking is performed, and that the driver can reliably perform the vehicle behavior operation even during the automatic braking. It is to provide a brake control device.

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided a running state detecting means for detecting a running state of a vehicle, and determining whether or not vehicle braking is necessary based on the running state of the vehicle detected by the running state detecting means. A braking request generating means for generating a braking request when vehicle braking is required; and a maximum deceleration and a maximum deceleration capable of operating a vehicle behavior by a driver in response to a braking request generated by the braking request generating means. A brake control device comprising: a deceleration that is equal to or lower than a speed increase gradient and braking control means that brakes the vehicle at a deceleration increase gradient.

According to the present invention, when the braking request is generated by the braking request generating means and the vehicle is braked by the braking control means based on the vehicle running state detected by the running state detecting means, the vehicle is reduced. The speed and the deceleration increase gradient are limited within a certain range in which the driver can operate the vehicle behavior. For this reason, even if the vehicle is braked by the braking control means, the driver hardly feels uncomfortable, and even during the braking of the vehicle by the braking control means, the vehicle behavior operation can be performed by the driver's will. .

Here, when it is determined by the braking request generating means that vehicle braking is necessary, the braking request generating means responds to a low response braking request or a high response braking request in accordance with the vehicle running state detected by the vehicle state detecting means. Generate a response braking request,
The braking control means suppresses the deceleration generated in the vehicle at the time of low response braking request to be equal to or less than the maximum deceleration and the maximum deceleration increase gradient at which the driver can operate the vehicle behavior. It is preferable that the speed is not suppressed below the maximum deceleration and the maximum deceleration increase gradient at which the driver can operate the vehicle behavior.

At this time, the braking performed by the braking control means is classified into a high response braking which requires a high response and a low response braking which does not require a high response. The low response braking request or the high response braking request is selectively generated when the braking request is generated based on Only when the low-response braking request is generated, the deceleration and the deceleration increase gradient of the vehicle are limited to a certain range where the driver can operate the vehicle behavior, and the high-response braking request is generated. Does not limit the vehicle deceleration and the deceleration increase gradient to within a certain range in which the driver can operate the vehicle behavior.

[0009] With this configuration, for low-response braking that does not require a high response, priority is given to the operation of the vehicle behavior of the driver, and the driver hardly feels uncomfortable.
Even while the vehicle is being braked by the braking control means, the vehicle behavior operation can be performed by the driver's will. On the other hand, at the time of high-response braking that requires high response, braking is performed for the purpose of complementing the vehicle behavior operation by the driver, and an ideal braking state can be formed earlier. As a result, low-response braking and high-response braking can be properly used to perform more advanced braking control.

Further, the traveling state detecting means detects the traveling speed of the own vehicle, the inter-vehicle distance to the preceding vehicle, and the relative speed as the vehicle traveling state, and the braking request generating means detects the traveling request by the traveling state detecting means. It is preferable to generate a low-response braking request based on the running state of the vehicle in order to perform automatic braking for maintaining a distance between the vehicle and the preceding vehicle.

With this configuration, low-response braking is performed for the purpose of maintaining an inter-vehicle distance with the preceding vehicle based on the traveling speed of the own vehicle detected as the vehicle traveling state and the inter-vehicle distance and relative speed with the preceding vehicle. Is done. At this time, the driver hardly feels a sense of discomfort, and the driver can perform the vehicle behavior operation according to his / her own intention even during the vehicle braking by the braking control means, and can perform comfortable driving. In addition, the distance between the vehicle and the preceding vehicle is maintained, which is preferable from the viewpoint of safety. Since the own vehicle performs low-response braking, the following vehicle does not give a sense of incongruity due to the braking of the own vehicle. Even if the vehicle is braked by the means, the following vehicle can sufficiently perform the vehicle behavior operation according to the driver's will.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a brake control device according to the present invention will be described with reference to the drawings.

The vehicle equipped with the brake control device of this embodiment automatically detects the preceding vehicle and automatically brakes the vehicle (ACC: Adaptive Cruse Control) in order to maintain a predetermined inter-vehicle distance.
l) It has a brake mechanism that can be activated. It should be noted that the ABS (Anti-
-lock Brake System), Traction Control (T
RC: TRaction Control, vehicle stability control (VSC: Ve)
The vehicle can also be braked during vehicle assistance (BA: Brake Assist), which assists emergency braking. In the present embodiment, the above-described braking during the ACC control is performed as the low-response braking, and the above-described braking during the ABS, TRC, VSC, and BA controls is performed as the high-response braking.

FIG. 1 shows a block diagram of a brake mechanism in which the brake control device according to the present embodiment is incorporated. This brake mechanism controls the brake oil pressure required during braking,
Either the hydraulic pressure generated in the master cylinder by the driver's operation of the brake pedal or the hydraulic pressure accumulated in the accumulator by the pump motor 2 is used. The operation of the brake pedal by the driver is detected from the on / off state of the stop lamp switch 3, and the operation speed and the operation treading force of the brake pedal operation by the driver increase the pressure of the master cylinder pressure sensor 4 which detects the pressure in the master cylinder. It is detected from the gradient and the pressure itself.

The hydraulic pressure generated by the master cylinder and the hydraulic pressure accumulated in the accumulator are transmitted to the wheel cylinders of the respective wheels via brake pipes using brake oil as a medium. A plurality of control valves 6 are arranged on the brake pipe, and these control valves 6 have a role of switching a hydraulic pressure transmission path and adjusting a hydraulic pressure transmission degree. The above-described pump motor 2 is connected to an ECU 1 that controls various controls of the vehicle, and is driven by electric power of a battery in accordance with a command from the ECU 1,
The brake oil stored in the reservoir tank is sent to the accumulator. The accumulator stores the brake oil delivered by the pump motor 2 under high pressure.

A pressure switch 5 is provided on a brake pipe from the accumulator to the wheel cylinder. The pressure switch 5 sends a low-pressure signal to the ECU 1 when the oil pressure on the brake pipe becomes equal to or lower than a predetermined lower limit pressure (here, about 15 MPa). Sends a signal to ECU1. When receiving the low pressure signal, the ECU 1 drives the pump motor 2 to increase the oil pressure in the accumulator,
When receiving the high voltage signal, the pump motor 2 is stopped, and the pressure in the accumulator is always maintained in a predetermined region. By the ECU 1 and the pressure switch 5, the pressure in the accumulator is always maintained within a predetermined range.

As shown in FIG. 1, the pump motor 2, the stop lamp switch 3, the master cylinder pressure sensor 4, the pressure switch 5, and all the control valves 6
Connected to U1. In addition to the above, various sensors for detecting the running state of the vehicle are connected to the ECU 1. Various sensors connected to the ECU 1 will be described below.

A laser radar sensor 7, which is an object detecting means for detecting an object in front of the vehicle, is mounted at the front of the vehicle, irradiates a laser beam forward, and uses the reflected light to determine the presence or absence of an object such as a preceding vehicle. It detects the distance to the object and the relative speed to the object. Needless to say, other sensors such as a millimeter wave radar using a millimeter wave instead of a laser beam can be used.

The wheel speed sensor 8 is attached to each wheel, and detects the rotation speed of each wheel. The ECU 1 calculates the vehicle speed of the vehicle based on the detection result of the wheel speed sensor 8. The yaw rate sensor 9 detects a yaw rate of the vehicle. The linear G sensor 10 detects acceleration in the front-rear direction and left-right direction of the vehicle. Steering angle sensor 11
Detects the steering angle and the turning angular velocity of the steering wheel. The shift position switch 12 detects a current shift position.

The ECU 1 determines the running state and driving state of the vehicle from the detection results of the various sensors described above. The ECU 1 to which the various sensors described above are connected,
It is composed of a microcomputer and controls the braking control and other controls of the vehicle. ECU 1 is engine 1
3 and the transmission 14, and also controls these. These various sensors function as running state detecting means for detecting the running state of the vehicle.
Functions as a braking request generating means for generating a braking request based on the detection results of various sensors, and the control valve 6
Together with the above, it also functions as braking control means for braking the vehicle.

The case where braking is performed by the brake control device having the above-described configuration will be briefly described. FIG. 2 shows a flowchart at the time of braking.

The detection results of the various sensors described above are successively captured by the ECU 1, and the ECU 1 performs calculations based on the various types of captured information to determine the vehicle running state (step 100). Next, based on the running state calculated by the ECU 1, the above-mentioned ACC, ABS, TRC, VS
The necessity of the C and BA control and, if the control is necessary, which control is to be performed are determined at regular intervals (for example, every several milliseconds) by a program stored in the ECU 1 (step 101). .

If it is determined that the ACC control is necessary, the ECU 1 generates an ACC control request that is a low-response braking request in order to perform braking during the ACC control that is a low-response braking. When it is determined that the ABS, TRC, VSC, and BA controls are necessary, the ECU 1 generates control requests that are high-response braking requests in order to perform the high-response braking during these controls. Here, the brake pedal operation by the driver is always performed during the ABS and BA controls.

First, the case where braking by ACC control is necessary, that is, low response braking is performed will be described. For example,
During the execution of the ACC control for running at a constant speed at the set speed,
When the laser radar sensor 7 detects a preceding vehicle traveling at a speed lower than the own vehicle speed, it is determined that braking by the ACC control is necessary.

If it is determined in step 101 that the braking by the ACC control is necessary, it is determined whether or not the execution condition of the braking by the ACC control is satisfied (step 102). If the execution condition is not satisfied in step 102, the process ends without performing braking. When the execution condition is satisfied, the ECU 1 calculates the vehicle running state from the inter-vehicle distance and relative speed with the preceding vehicle detected by the laser radar sensor 7 and the wheel speed detected by the wheel speed sensor 8. A target deceleration during braking is calculated from the traveling speed of the vehicle. A control signal is sent from the ECU 1 to the control valve 6 based on the calculated target deceleration (step 103),
The hydraulic pressure stored in the accumulator is transmitted to the wheel cylinder to brake the vehicle.

During braking, the longitudinal deceleration of the vehicle is:
The deceleration and the deceleration increase gradient generated in the vehicle by the braking during the ACC control, which are detected by the linear G sensor 10, are less than or equal to the maximum deceleration and the maximum deceleration increase gradient at which the driver can control the vehicle behavior. To be suppressed. Here, the deceleration and the deceleration increasing gradient generated in the vehicle by the control of the control valve 6 by the ECU 1 are suppressed to be equal to or less than the above-described maximum deceleration and the maximum deceleration increasing gradient. In the present embodiment, the brake oil pressure (see FIG. 3 (b)) is determined in advance so that the deceleration during braking has a predetermined waveform (see FIG. 3 (a)). The control valve 6 is controlled by the ECU 1 as the target oil pressure. At the time of the ACC control, in addition to the above-described braking control, control for the engine 13 and the transmission 14 may be performed in parallel.

As shown in FIG. 3A, the predetermined maximum value Gm and the increasing gradient θg of the deceleration waveform are set to be equal to or less than the above-described maximum deceleration and the maximum deceleration increasing gradient. The maximum deceleration and the maximum deceleration increase gradient for which the driver can control the vehicle behavior are 0.3G and 0.2G / sec, respectively.
It is preferred that: That is, at the time of braking (low-response braking) during ACC control, it is preferable that the deceleration generated in the vehicle is set to 0.3 G or less and the increasing gradient is set to 0.2 G / sec or less.

If the maximum deceleration exceeds 0.3 G or the maximum deceleration increase gradient exceeds 0.2 G / sec, the braking force generated in the vehicle is large, and the change is large, giving the driver an uncomfortable feeling. Therefore, it is preferable that the maximum deceleration and the maximum deceleration increase gradient are 0.3 G and 0.2 G / sec or less, respectively. The maximum deceleration and the maximum deceleration increase gradient are
It is preferable that they are 0.3G and 0.2G / sec or less, respectively.
It is particularly preferable to set the speed to 0.2 G or 0.1 G / sec or less, respectively, because the uncomfortable feeling given to the driver is further reduced.

On the other hand, in step 101, ABS,
When it is determined that the braking by the TRC, VSC, and BA controls, that is, the high-response braking is necessary, it is determined whether or not each execution condition of the braking by these controls is satisfied (step 104). If the execution condition is not satisfied in step 104, the process ends without performing braking. When the execution condition is satisfied, the ECU 1 detects the vehicle running state from various sensors, and calculates the target deceleration during braking based on the detected vehicle state amount. Based on the calculated target deceleration, a control signal is sent from the ECU 1 to the control valve 6 (step 105).
The hydraulic pressure generated in the master cylinder and the hydraulic pressure accumulated in the accumulator are transmitted to the wheel cylinder to brake the vehicle.

During high-response braking, the deceleration and the deceleration increasing gradient generated in the vehicle are suppressed so as to be equal to or less than the maximum deceleration and the maximum deceleration increasing gradient at which the driver can control the vehicle behavior. Absent. That is, the deceleration waveform during braking may have a large maximum value Gm and a large increase gradient θg as illustrated in FIG. 4A.
That is, during high-response braking, the deceleration and the deceleration increase gradient are not limited, so that the vehicle behavior can be quickly controlled with a large braking force. The brake oil pressure corresponding to the deceleration illustrated in FIG. 4A is shown in FIG. 4B, and the brake oil pressure is realized by controlling the control valve 6 by the ECU 1. Note that AB
At the time of S, TRC, VSC, and BA control, in addition to the above-described braking control, control for the engine 13 and the transmission 14 may be performed in parallel.

According to the brake control device of the present embodiment,
When a low response braking request is generated by the ECU 1 and the vehicle is braked based on the vehicle running state detected by the laser radar sensor 7 that is the running state detecting means, the deceleration and the deceleration increasing gradient of the vehicle are determined by: Since the vehicle behavior operation by the driver is limited within a certain range, the driver can perform the vehicle behavior operation according to the driver's will with almost no discomfort during low response braking.

In the present embodiment, the braking performed by the braking control means is classified into high response braking and low response braking, and when the braking request is generated by the braking request generating means, it is determined according to the vehicle running state. Thus, a low response braking request and a high response braking request are selected. Only when the low-response braking request is generated, the deceleration and the deceleration increase gradient of the vehicle are limited to a certain range where the driver can operate the vehicle behavior, and the high-response braking request is generated. Does not limit the vehicle deceleration and the deceleration increase gradient to within a certain range in which the driver can operate the vehicle behavior. For this reason, in the low-response braking, the vehicle behavior operation of the driver is prioritized, and the vehicle behavior operation of the driver's will can be performed with almost no discomfort to the driver. On the other hand, at the time of high-response braking, braking is performed for the purpose of complementing the vehicle behavior operation by the driver, and an ideal braking state can be formed earlier. As a result, low-response braking and high-response braking can be properly used to perform more advanced braking control.

The brake control device according to the present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, the deceleration waveform at the time of braking during ACC control is controlled to be a predetermined waveform. However, the deceleration and the deceleration increasing gradient of the vehicle during braking are the maximum deceleration. And a method of controlling sequentially so as to be equal to or less than the maximum deceleration increase gradient.

[0034]

According to the brake control device of the present invention, it is determined whether or not vehicle braking is necessary based on the running state detecting means for detecting the running state of the vehicle and the running state of the vehicle detected by the running state detecting means. A braking request generating means for generating a braking request when vehicle braking is required; and a maximum deceleration and a maximum deceleration capable of operating a vehicle behavior by a driver in response to a braking request generated by the braking request generating means. Since the vehicle is provided with a deceleration that is equal to or lower than the speed increase gradient and braking control means that brakes the vehicle at a deceleration increase gradient, the driver does not feel uncomfortable even when the automatic braking is performed. The operation can be performed reliably.

[Brief description of the drawings]

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

FIG. 2 is a flowchart when braking is performed by an embodiment of the brake control device of the present invention.

FIG. 3 is a graph showing (a) vehicle deceleration and (b) brake oil pressure during low response braking.

FIG. 4 is a graph showing (a) vehicle deceleration and (b) brake oil pressure during high response braking.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... ECU, 2 ... Pump motor, 3 ... Stop lamp switch, 4 ... Master cylinder pressure sensor, 5 ... Pressure switch, 6 ... Control valve, 7 ... Laser radar sensor, 8 ... Wheel speed sensor, 9 ... Yaw rate sensor, 10 ... Linear G sensor, 11 ... Steering angle sensor, 12 ... Shift position switch, 13 ... Engine, 14 ... Transmission

Claims (3)

[Claims] 1. A running state detecting means for detecting a running state of a vehicle, and based on a running state of the vehicle detected by the running state detecting means, it is determined whether or not vehicle braking is necessary. A braking request generating means for generating a braking request in a certain case; a braking request generated by the braking request generating means; A brake control device for braking the vehicle at a speed and a deceleration increasing gradient. 2. When the braking request generating means determines that vehicle braking is necessary, the braking request generating means responds to the low-response braking request in accordance with the vehicle running state detected by the vehicle state detecting means. Or, a high response braking request is generated, and the braking control means suppresses the deceleration generated in the vehicle at the time of the low response braking request to a maximum deceleration and a maximum deceleration increasing gradient at which the vehicle behavior operation by the driver is possible, The brake control device according to claim 1, wherein a deceleration generated in the vehicle at the time of a high response braking request is not suppressed below a maximum deceleration and a maximum deceleration increasing gradient at which a driver can operate the vehicle behavior. 3. The traveling state detecting means detects a traveling speed of the own vehicle, an inter-vehicle distance to a preceding vehicle, and a relative speed as a vehicle traveling state, and the braking request generating means detects the traveling state by the traveling state detecting means. 3. The brake control device according to claim 2, wherein a low-response braking request is generated for performing automatic braking for maintaining a distance between the vehicle and a preceding vehicle based on the vehicle running state.