JPH0826099A - Electronically controlled brake device - Google Patents

Abstract

PURPOSE:To realize fail-safe even in case of the sensor pressure trouble or when a pressure generator fails, by installing a solenoid valve control part for outputting an opening/closing instruction to the first and the second solenoid valves, on the basis of the pressure instruction value supplied to the pressure generator and the signal of a pressure sensor. CONSTITUTION:An ECU 17 calculates the pressure instruction value on the basis of the signal supplied from a brake signal source 2, and outputs each pressure instruction value from the signal generators 11-14, and controls each drive of the pressure generators 11-14. It is judged if the difference between each pressure instruction value supplied to each pressure generator 11-14 for each wheel and each feedback signal supplied from the pressure sensors 3-6 is over a certain threshold value or not. For example, when the difference between the pressure instruction value supplied to a left pressure generator 11 on a front wheel side and the feedback signal supplied from the pressure sensor 3 is over a certain threshold value, an error flag Error 1 is set so as to detect the abnormale place.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled braking system for vehicles.

[0002]

2. Description of the Related Art As a technique in such a field, Japanese Patent Laid-Open No.
There is one described in Japanese Patent Publication No. 9-20754. This is to avoid the situation where sudden braking is impossible by calculating the maximum capacity that can be obtained in the brake that is controlled to obtain the effect according to the brake pedal force and issuing an alarm when this becomes a certain value or less. Has been described.

[0003]

By the way, based on the operation signal of the brake pedal (pedal force, pedal stroke, etc.), each wheel cylinder is independently connected to each of the four front, rear, left and right wheel cylinders by a pressure generator. In an electronic control device that controls pressure, a method of detecting the pressure of each wheel cylinder and performing feedback control can be considered. This feedback control is performed by the ECU (Electr
onic Control Unit) so that the deviation between the pressure command value from the onic control unit) and the signal from the pressure sensor becomes small. Here, the wheel cylinder is to generate a braking force on the brake shoe by its pressure.

However, if any one of the pressure sensors or any one of the pressure generators fails, the following problems may occur. That is, if the pressure sensor has a failure, for example, a 0-point offset, a phenomenon in which no output is produced, or a change in gain, the pressure of the wheel cylinder is different from the pressure command value from the ECU. Also, in the case of normal control other than controlling the control force of the left and right wheels independently, such as a straddling road where the friction coefficient μ of the left and right road surfaces is greatly different, control during turning etc., the pressure of the left and right wheel cylinders may be the same pressure, The ECU sends equal pressure values to the corresponding two pressure generators. However, as described above, when the pressure sensor fails, a pressure difference occurs between the left and right wheel cylinders, and the vehicle behavior during braking becomes unstable. When the power difference is extremely large, there is a danger of a spin state.

There is a similar risk when another pressure sensor fails, or when any one of the pressure generating devices fails and does not operate correctly. Therefore, the present invention has been made in view of the above-mentioned problems, and a sensor pressure failure,
An object of the present invention is to provide an electronically controlled braking device that can realize fail-safe even if there is a failure in the pressure generating device.

[0006]

The present invention provides an electronically controlled brake device having the following construction in order to solve the above problems. That is, a pressure generator that generates pressure in the wheel cylinders of the four wheels and a pressure sensor that detects the pressure of the wheel cylinders of the four wheels are provided, and information from the brake signal source indicating the brake operation state is displayed. Based on the above, the first left and right wheel cylinders are connected to an electronically controlled brake device that outputs a pressure command value to a pressure generator and performs pressure control using a signal from a pressure sensor as a feedback value.
Second hydraulic pipe connecting the left and right wheel cylinders on the rear side
Between the left and right wheel cylinders on the rear wheel side, and the first solenoid valve on the second hydraulic line for communicating and blocking the front and left wheel cylinders on the front wheel side. And a first solenoid valve for connecting and disconnecting. The solenoid valve control unit, based on the pressure command value to the pressure generator, the signal of the pressure sensor, further based on the mutual comparison of the signals from the pressure sensor, failure from a plurality of preset failure modes A failure mode detection unit that detects a mode and an error flag formation unit that forms an error flag corresponding to the detected failure mode, and determines a failure mode based on the error flag to determine a predetermined pressure generator and pressure sensor. An opening / closing command is output to the first and second solenoid valves by using the command.

The solenoid valve control unit operates when it is determined that there is a difference of a certain threshold value or more between the signal output as the pressure command value to the pressure generator and the signal from the pressure sensor, and the solenoid valve control unit operates. Side or rear wheel side left and right wheel cylinders are in communication. The solenoid valve control unit makes the front wheel side or the rear wheel side left and right wheel cylinders in a communication state when the vehicle is in a stopped state, between the signals from the pressure sensor that detects the pressure of the front wheel side or the rear wheel side left and right wheel cylinders, When it is determined that there is a difference equal to or more than a certain threshold value, the corresponding front wheel side or rear wheel side left and right wheel cylinders are left in the communicating state.

[0008]

According to the electronically controlled brake device of the present invention, the opening / closing command is output to the first and second solenoid valves based on the pressure command value to the pressure generator and the signal of the pressure sensor. Adjust the pressure difference between the wheel cylinders,
It is possible to realize fail-safe against failure of the pressure sensor and the pressure generator.

That is, when it is judged that there is a difference of a certain threshold value or more between the signal output as the pressure command value to the pressure generator and the signal from the pressure sensor, the operation is activated and the front wheel side or the rear wheel side is activated. By making the left and right wheel cylinders in the communicating state, it is possible to equalize the pressure between the front and rear wheel cylinders, stabilize the vehicle behavior, and avoid spin based on the braking force difference. In this case, at the same time, the control using the pressure generating device and the pressure sensor of the abnormal one is stopped and the control of only the normal one is switched.

Further, when the vehicle is at a standstill, the left and right wheel cylinders on the front wheel side or the rear wheel side are brought into communication with each other, and a certain threshold value is set between signals from a pressure sensor for detecting the pressure of the left and right wheel cylinders on the front wheel side or the rear wheel side. If it is judged that there is a difference above, there is a left-right braking force difference when the gain of the pressure sensor changes by leaving the corresponding front wheel side or rear wheel side left and right wheel cylinders in a communicating state. You will be able to deal with the case.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an electronically controlled braking device according to an embodiment of the present invention. As shown in the figure, the wheel cylinders 9, 10, 11 whose pressures are controlled by the pressure generators 11, 12, 13 and 14 independently connected to the four wheels of the vehicle are connected to the electronically controlled braking device. Pressure sensors 3, 4, 5 and 6 are provided in the vicinity of 12 and 12. The hydraulic pipes 18 and 19 connect the left and right wheel cylinders 7 and 8 on the front wheel side and the left and right wheel cylinders 9 and 10 on the rear wheel side, respectively. The solenoid valves 15 and 16 are normally shut-off solenoid valves provided in the middle of the hydraulic pipes 18 and 19 for communicating and shutting off the left and right wheel cylinders.

The ECU 17 for inputting information from the brake signal source 2 which issues a brake signal based on the pedaling force received by the brake pedal 1 is provided with the pressure generators 11, 12, 13 and 1.
4 outputs the pressure command value to the pressure sensors 3, 4, 5 and 6
Is inputted as a feedback value to perform feedback control to the pressure generators 11, 12, 13 and 14. The ECU 17 also outputs an opening / closing command to the solenoid valves 15 and 16 as needed. The details of the ECU 17 will be described below.

As shown in FIG. 1, the ECU 17 is based on the difference between the command value to the pressure generator and the feedback signal from the pressure sensor, and further based on the mutual comparison of the signals from the pressure sensor. A failure mode detection unit 171 that detects a failure mode from a plurality of set failure modes, and an error flag formation unit 172 that forms an error flag corresponding to the detected failure mode are provided, and the failure mode is based on the error flag. Solenoid valve control unit 1 for controlling the solenoid valves 15 and 16 using a predetermined pressure generator and pressure sensor.
73 is provided. The following Tables 1 and 2 show error flag types Error1 to Error performed by the ECU 17.
The details of the failure mode corresponding to No. 8 and the coping method will be shown.

[0014]

[Table 1]

[0015]

[Table 2]

2 and 3 are flowcharts (Nos. 1 and 2) for explaining the control operation of the ECU 17. In step S101, control is started. Step S1
At 02, the ECU 17 checks whether or not a failure-related error flag is set. This judgment is "N
If any error flag is set at "O", the process proceeds to step S113. If not, that is, if this determination is "YES", the process proceeds to step S103.

In step S103, it is determined whether or not the brake is operating based on the information from the brake signal source 2. If this determination is "YES", that is, if the brake signal is operating the brake pedal, it is considered that the brake is being operated, and the process proceeds to step S105. If this determination is "NO", the process proceeds to step S104. In step S104, the wheel cylinder pressure when the brake is not operating is regarded as the atmospheric pressure, and the zero point correction is performed based on the value, and the process returns to step S102. At this step, one of the failure modes of the pressure sensor
The difference between the pressure command value generated by the zero point offset of the pressure sensor and the actual pressure is resolved.

In step S105, the ECU 17 calculates a pressure command value based on the signal from the brake signal source 2 and outputs the pressure command value to the pressure generators 11, 12, 13 and 14 to generate the pressure generators 11, 12 ,. Control the drive of 13 and 14. In step S106, it is determined whether the difference between the pressure command value to the pressure generators 11, 12, 13 and 14 of each wheel and the feedback signal from the pressure sensors 3, 4, 5 and 6 is equal to or more than a certain threshold value. to decide. For example, in FIG. 1, when the difference between the pressure command value to the left pressure generating device 11 on the front wheel side and the feedback signal from the pressure sensor 3 is equal to or more than a certain threshold value, the process proceeds to step S111. Then, as shown in Table 1, after the error flag Error1 is set so that the location of the abnormality can be recognized, the process proceeds to step S113. Also, when the same occurs in other pressure sensors and pressure generators, after setting an error flag as shown in Table 1, the process proceeds to step S113.

Next, the error flag routine of step S113 will be described with reference to FIG. Step S11
In 5, it is confirmed whether the right and left wheel cylinders of the front and rear wheels are in communication with each other by whether or not the solenoid valve is operating. If it is not in the communication state, the process proceeds to step S116, and if it is in the communication state, the process proceeds to step S17.

In step S116, the left and right wheel cylinders are brought into communication with each other by the solenoid valve, and in step S11
Proceed to 7. In step S117, step S10
Similar to step 3, it is determined whether the brake is operating.
If it is in operation, the process proceeds to step S118, and if it is not in operation, the process proceeds to step S120.

In step S118, it is checked what kind of error flag is set. Step S11
In FIG. 9, as shown in Table 1, the pressure generator and the pressure sensor to be used are determined according to the abnormal place (for example, if Error1 is standing in Table 1, the pressure generators for the right front wheel and the right rear wheel are determined. , The pressure control is performed based on the signal from the brake signal source 2, and the process returns to step S117.

In step S120, step S1
The same 0 point correction operation as in 04 is performed on the pressure sensor, and the process returns to step S102. This step S106, 111, 1
By means of 13, it is possible to eliminate the pressure difference between the left and right wheels that occurs at the time of the failure of the pressure generator described above, or the failure of the pressure sensor "no output", and it is possible to prevent spin during braking. Become. However, when the gain of the pressure sensor changes, for example, when the pressure sensor is set to output 10 MPa at 1 V, 10 MPa is output at 1.5 V for some reason. Although there is no difference between the command value and the signal from the pressure sensor, a pressure difference actually occurs between the left and right wheel cylinders, and therefore the method of step S106 is not an appropriate measure. Therefore, as a measure against the change in the gain of the pressure sensor, there is a control operation after step S107 in FIG. 2, and this control operation will be described below.

In step S107, it is determined whether the vehicle is stopped. If it is not in the stopped state, the process returns to step S102, and if it is in the stopped state, the process proceeds to step S108. In step S108, the solenoid valves 15 and 16 are operated to bring the left and right wheel cylinders into communication. This is for two pressure sensors on the same hydraulic line,
When the gain of one pressure sensor is changing, there is a difference between the two output values. Therefore, if the pressures of the left and right wheel cylinders are made to be in the communicating state and they are made equal, then it is determined whether the gain of the pressure sensor is changing. This is because it will be possible to confirm.

If it is determined in step S109 that the difference between the left and right pressure sensors 3, 4 or 5, 6 is equal to or more than the threshold value, the process proceeds to step S112. This is because, for example, even if it is known that there is a difference in the output values of the pressure sensors 3 and 4, it cannot be determined which of the pressure sensors has a change in gain, and this determination is made. If there is no left-right pressure difference, step S11
Go to 0.

In step S112, as shown in Table 2, it is judged that there is an abnormality in the pressure sensor and the pressure generator that output low values in the front wheels, and error flags Error5 and Error6 are set so that the abnormality can be recognized, It is judged that there is an abnormality in the pressure sensor and the pressure generator that output a high value on the wheel, and the error flag Error
Set up 7 and 8. This is because if the braking force of the rear wheels is too high compared to the braking force of the front wheels during braking, the rear wheels will be locked and it will be in a dangerous state. This is to secure a lower braking force by selecting a pressure with a high gain for the rear wheels.

After performing the same operation as described above in step S113, in step S119, as shown in Table 2, the pressure generator and the pressure sensor to be used are determined according to the abnormal portion (for example, the table Assuming that Error 5 is standing at 2, the pressure generating device for the right front wheel and the right rear wheel,
Only the pressure sensor is used), pressure control is performed based on the signal from the brake signal source 2, and the process returns to step S117. When the process proceeds to step S120, the same operation as step S104 is performed, and the process returns to step S102.

In step S110, the solenoid valve 15,
The left and right wheel cylinders are separated again by 16 and the process returns to step S102. According to the present embodiment, in the four-wheel independent electronically controlled brake, by disposing the hydraulic pipes connecting the left and right wheel cylinders and the solenoid valves for connecting and disconnecting the front and rear wheels, the pressure generator or the pressure sensor is broken. Even if this occurs, the pressure difference between the left and right wheel cylinders will not occur, and therefore the spin state of the vehicle will not occur. Further, it becomes possible to cope with the case where there is a difference between the left and right braking forces when the gain of the pressure sensor changes.

Further, in the above-mentioned embodiment, the operation is described based on the signal of the brake pedal, but the invention is not limited to this, and it goes without saying that a manual brake or the like is also possible. .

[0029]

As described above, according to the present invention, based on the pressure command value to the pressure generator and the signal of the pressure sensor,
Since the opening / closing command is output to the first and second solenoid valves, the pressure difference between the left and right wheel cylinders can be adjusted, and fail-safe against failure of the pressure sensor and the pressure generator can be realized. That is, when it is determined that there is a difference of a certain threshold value or more between the signal output as the pressure command value to the pressure generator and the signal from the pressure sensor, the front wheel side or the rear wheel side left and right wheel cylinders are activated. Since it is in the communication state, the pressure between the left and right wheel cylinders on the front wheel side or the rear wheel side becomes equal, the vehicle behavior is stable, and when the vehicle is in the stopped state, the left and right wheel cylinders on the front wheel side or the rear wheel side are in the communication state, If it is determined that there is a certain threshold difference between the signals from the pressure sensors that detect the pressures of the front and rear wheel cylinders, the corresponding front and rear wheel cylinders are connected. Since the state is left as it is, it becomes possible to cope with the case where there is a difference in the left and right braking forces when the gain of the pressure sensor changes.

[Brief description of drawings]

FIG. 1 is a diagram showing an electronically controlled brake device according to an embodiment of the present invention.

FIG. 2 is a flowchart (part 1) illustrating a control operation of an ECU 17.

FIG. 3 is a flowchart (part 2) explaining a control operation of the ECU 17.

[Explanation of symbols]

 3, 4, 5, 6 ... Pressure sensor 7, 8, 9, 10 ... Wheel cylinder 11, 12, 13, 14 ... Pressure generating device 15, 16 ... Solenoid valve 17 ... ECU 18, 19 ... Hydraulic pipe 173 ... Solenoid valve Control unit

Front page continuation (72) Inventor Ikuo Hayashi 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute, Inc.

Claims (3)

[Claims] 1. A brake signal source for indicating a brake operation state, comprising a pressure generating device for generating a pressure in a wheel cylinder of each of the four wheels and a pressure sensor for detecting a pressure of a wheel cylinder of each of the four wheels. In the electronically controlled braking device that outputs the pressure command value to the pressure generator based on the information of the above and controls the pressure using the signal from the pressure sensor as the feedback value, the first hydraulic pipe connecting the left and right wheel cylinders on the front wheel side and the rear wheel A second hydraulic pipe that connects the left and right wheel cylinders, and a first solenoid valve that is arranged in the first hydraulic pipe to connect and disconnect the front wheel side left and right wheel cylinders, and are arranged in the second hydraulic pipe. Based on the pressure command value to the pressure generating device and the signal of the pressure sensor, based on the first solenoid valve for connecting and disconnecting the left and right wheel cylinders on the rear wheel side. Electronic control brake system, characterized in that it comprises a solenoid valve controller for outputting a closing command to the solenoid valve. 2. The solenoid valve control unit operates when it is determined that there is a difference of a certain threshold value or more between a signal output as a pressure command value to the pressure generator and a signal from a pressure sensor. The electronically controlled brake device according to claim 1, wherein the front wheel side or the rear wheel side left and right wheel cylinders are brought into communication with each other. 3. The solenoid valve control unit sets a front wheel side or a rear wheel side left and right wheel cylinders in a communicating state when the vehicle is stopped, and a pressure sensor for detecting a pressure of the front wheel side or the rear wheel side left and right wheel cylinders. 2. When it is determined that there is a difference equal to or more than a certain threshold value between the signals of, the corresponding front wheel side or rear wheel side left and right wheel cylinders are left in a communicating state. Electronically controlled braking device.