JP2004352150A - Brake control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promptly determine an active wheel speed sensor to be in bad condition due to lowering of power supply voltage during operation of a liquid pressure regulating means and to surely determine the active wheel speed sensor to be in bad condition during non-operation of the liquid pressure regulating means in a brake control device for a vehicle provided with the liquid pressure regulating means capable of regulating brake liquid pressure of a wheel brake, the active wheel speed sensor detecting a wheel speed, and a control unit controlling operation of the liquid pressure regulating means based on the wheel speed detected by the active wheel speed sensor. <P>SOLUTION: The control unit 16 determines the active wheel speed sensors 17A to 17D to be in bad condition based on a condition that during the operation of the liquid pressure regulating means 4, a state of the power supply voltage applied to the active wheel speed sensor 17A to 17D being lowered not more than a set voltage lasts for a shorter time comparing to the time of non-operation of the liquid pressure regulating means 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a hydraulic pressure adjusting means capable of adjusting a brake hydraulic pressure of a wheel brake, an active wheel speed sensor for detecting a wheel speed, and the hydraulic pressure adjustment based on a wheel speed detected by an active wheel speed sensor. And a control unit for controlling the operation of the pressure means.
[0002]
[Prior art]
A vehicle brake control device that adjusts a brake fluid pressure of a wheel brake based on a wheel speed detected by a wheel speed sensor to perform, for example, anti-lock brake control is already known, for example, from Patent Document 1 and the like.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-238630
[Problems to be solved by the invention]
By the way, when an active wheel speed sensor using a hall element or the like is used as a wheel speed sensor, if the power supply voltage applied to the active wheel speed sensor decreases, an output signal from the active wheel speed sensor may not be obtained. In such a case, there is a possibility that the wheel speed is erroneously determined to be 0 km / h and anti-lock brake control is started even though it is unnecessary, and the brake fluid pressure of the wheel brake is undesirably reduced. There is.
[0005]
In order to prevent such a situation from occurring, the power supply voltage may be constantly monitored.However, during operation of the hydraulic pressure adjusting means, erroneous operation control of the hydraulic pressure adjusting means is not maintained. While it is necessary to promptly determine a drop in the power supply voltage, when the hydraulic pressure regulating means is not operating, the power supply voltage may temporarily decrease due to, for example, the operation of a starter motor. It is required to reliably determine a drop in the power supply voltage except for a temporary drop in the power supply voltage.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is possible to prevent malfunction of an active wheel speed sensor due to a decrease in power supply voltage quickly when the hydraulic pressure adjusting means is activated, and reliably when the hydraulic pressure adjusting means is not activated. It is an object of the present invention to provide a vehicular brake control device that can make a judgment.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a hydraulic pressure adjusting means capable of adjusting a brake hydraulic pressure of a wheel brake, an active wheel speed sensor for detecting a wheel speed, and a wheel detected by an active wheel speed sensor. A control unit for controlling the operation of the hydraulic pressure adjusting means based on a speed, wherein the control unit is applied to the active wheel speed sensor when the hydraulic pressure adjusting means is activated. It is determined that the active wheel speed sensor is malfunctioning when the state in which the power supply voltage has dropped below the set voltage lasts for a shorter time than when the hydraulic pressure regulating means is not operated.
[0008]
According to such a configuration, when the hydraulic pressure adjusting means is operated to adjust the brake hydraulic pressure of the wheel brake, the state in which the power supply voltage applied to the active wheel speed sensor has dropped below the set voltage is compared. It is possible to determine that the active wheel speed sensor is malfunctioning by keeping it for a very short time, and to quickly determine the malfunction of the active wheel speed sensor so that the erroneous operation control of the hydraulic pressure adjusting means does not continue. When the hydraulic pressure adjusting means is not operated, the state in which the power supply voltage has dropped below the set voltage is maintained for a relatively long time so that it is determined that the active wheel speed sensor is malfunctioning. In the event that the power supply voltage temporarily drops due to factors such as the above, the malfunction of the active wheel speed sensor due to the drop in the power supply voltage is reliably determined. Rukoto can.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described based on an embodiment of the present invention shown in the attached drawings.
[0010]
1 to 4 show one embodiment of the present invention. FIG. 1 is a diagram showing a hydraulic circuit configuration of a vehicle brake control device, and FIG. 2 is a connection circuit configuration of an active wheel speed sensor and a control unit. FIG. 3 is a diagram showing a part of a flowchart showing a procedure for determining a malfunction of an active wheel speed sensor, and FIG. 4 is a diagram showing a remaining portion of a flowchart showing a procedure for determining a malfunction of an active wheel speed sensor.
[0011]
First, in FIG. 1, a tandem type master cylinder M is provided with first and second output ports 1A and 1B for generating a brake fluid pressure according to a depression force applied to a brake pedal P by a vehicle driver, and is used for a left front wheel. Wheel brake 2A, right rear wheel brake 2B, right front wheel brake 2C, left rear wheel brake 2D, and first and second individually connected to the first and second output ports 1A, 1B. Hydraulic pressure adjusting means 4 is provided between the output hydraulic pressure paths 3A and 3B.
[0012]
The hydraulic pressure adjusting means 4 includes first, second, and third wheel brakes respectively corresponding to the front left wheel brake 2A, the rear right wheel brake 2B, the front right wheel brake 2C, and the rear left wheel brake 2D. And fourth normally open solenoid valves 6A to 6D, first, second, third and fourth check valves 7A to 7D connected in parallel to the normally open solenoid valves 6A to 6D, respectively, and the respective wheels First, second, third and fourth normally closed solenoid valves 8A to 8D individually corresponding to the brakes 2A to 2D, and first first and second output hydraulic pressure paths 3A and 3B respectively corresponding to the first and second output hydraulic pressure paths 3A and 3B. And second reservoirs 9A and 9B, plunger-type first and second pumps 10A and 10B having suction valves 11A and 11B connected to the first and second reservoirs 9A and 9B and having discharge valves 13A and 13B, respectively. , Both pumps 10A, 10B A single common electric motor 12 that moves, and orifices 14A, 14B interposed between the two pumps 10A, 10B and the two output hydraulic lines 3A, 3B. The operations of the normally open solenoid valves 6A to 6D, the normally closed solenoid valves 8A to 8D, and the electric motor 12 are controlled by the control unit 16.
[0013]
The first normally open solenoid valve 6A is provided between the first output hydraulic pressure passage 3A and the left front wheel brake 2A, and the second normally open solenoid valve 6B is provided between the first output hydraulic pressure passage 3A and the right rear wheel. The third normally-open solenoid valve 6C is provided between the second output hydraulic path 3B and the right front wheel brake 2C, and the fourth normally-open solenoid valve 6D is provided between the second output hydraulic pressure path 3B and the right front wheel brake 2C. It is provided between the output hydraulic pressure path 3B and the left rear wheel brake 2D.
[0014]
The first to fourth check valves 7A to 7D are connected in parallel to the normally open solenoid valves 6A to 6D so as to allow the flow of the brake fluid from the corresponding wheel brakes 2A to 2D to the master cylinder M. Is done.
[0015]
The first normally closed solenoid valve 8A is provided between the left front wheel brake 2A and the first reservoir 9A, and the second normally closed solenoid valve 8B is provided between the right rear wheel brake 2B and the first reservoir 9A. The third normally closed solenoid valve 8C is provided between the right front wheel brake 2C and the second reservoir 9B, and the fourth normally closed solenoid valve 8D is provided with the left rear wheel brake 2D and the second reservoir. 9B.
[0016]
Such a hydraulic pressure adjusting means 4 communicates between the master cylinder M and the wheel brakes 2A to 2D and establishes a connection between the wheel brakes 2A to 2D and the reservoirs 9A and 9B at the time of steady braking in which each wheel is not likely to be locked. Cut off. That is, the normally-open solenoid valves 6A to 6D are demagnetized and opened, and the normally-closed solenoid valves 8A to 8D are demagnetized and closed, and output from the first output port 1A of the master cylinder M. The brake fluid pressure acts on the left front wheel brake 2A via the first normally-open solenoid valve 6A and acts on the right rear wheel brake 2B via the second normally-open solenoid valve 6B. The brake fluid pressure output from the second output port 1B of the master cylinder M acts on the right front wheel brake 2C via the third normally-open solenoid valve 6C, and causes the fourth normally-open solenoid valve 6D to operate. Acts on the rear left wheel brake 2D via the rear wheel.
[0017]
When the wheels are about to enter the locked state during the braking, the control unit 16 controls the operation of the hydraulic pressure adjusting means 4 so as to perform the antilock brake control. At the start, the hydraulic pressure adjusting means 4 shuts off the master cylinder M and the wheel brakes 2A to 2D at a portion corresponding to the wheel which is about to enter the locked state, and also connects the wheel brakes 2A to 2D and the reservoirs 9A and 9B. To communicate. That is, among the first to fourth normally-open solenoid valves 6A to 6D, the normally-open solenoid valves corresponding to the wheels that are about to enter the locked state are excited and closed, and the first to fourth normally-closed solenoid valves are opened. Of the solenoid valves 8A to 8D, the normally closed solenoid valves corresponding to the wheels are excited and opened. As a result, a part of the brake fluid pressure of the wheel that is about to enter the locked state is absorbed by the first reservoir 9A or the second reservoir 9B, and the brake fluid pressure of the wheel that is about to enter the locked state is reduced. Will be.
[0018]
When the brake fluid pressure is kept constant, the fluid pressure regulating means 4 is in a state of disconnecting the wheel brakes 2A to 2D from the master cylinder M and the reservoirs 9A and 9B. That is, the normally open solenoid valves 6A to 6D are excited and closed, and the normally closed solenoid valves 8A to 8D are demagnetized and closed. When the brake fluid pressure is further increased, the normally open solenoid valves 6A to 6D may be demagnetized and opened, and the normally closed solenoid valves 8A to 8D may be demagnetized and closed.
[0019]
By controlling the demagnetization and excitation of each of the normally-open solenoid valves 6A to 6D and each of the normally-closed solenoid valves 8A to 8D by the control unit 16 in this manner, braking can be efficiently performed without locking the wheels. .
[0020]
During braking, the second and fourth normally-open solenoid valves 6B and 6D corresponding to the left and right rear wheels of the first to fourth normally-open solenoid valves 6A to 6D of the hydraulic pressure regulating means 4 are closed. Thereby, it is also possible to perform the braking force distribution control for performing the braking force distribution before and after.
[0021]
The control unit 16 includes active wheel speed sensors 17A and 17B for detecting wheel speeds of the left front wheel and the right rear wheel, and active wheel speed sensors 17C and 17D for detecting wheel speeds of the right front wheel and the left rear wheel, respectively. The control unit 16 executes the antilock brake control and the braking force distribution control based on the wheel speed detected by each of the active wheel speed sensors 17A to 17D.
[0022]
In FIG. 2, a first terminal 18 of the active wheel speed sensor 17A is connected to a line L1 connected to a vehicle-mounted battery 21 via a fuse 22, a diode 23, and a current limiting circuit 24 in response to conduction of an ignition switch 20. . A protection capacitor 25 is provided between the first and second terminals 18 and 19 of the active wheel speed sensor 17A, and the second terminal 19 is grounded via a detection resistor 26.
[0023]
The output from the second terminal 19 of the active wheel speed sensor 17A is converted into a pulse signal by the waveform shaping circuit 27 and input to the control unit 16. Further, the control unit 16 can detect the voltage of the vehicle-mounted battery 21 applied to the active wheel speed sensor 17A by a line L2 connected between the fuse 22 and the diode 23, and the detected voltage indicates the operation of the active wheel speed sensor 17A. Is determined to be equal to or lower than the minimum operating voltage that guarantees that the active wheel speed sensor 17A is malfunctioning due to a decrease in the power supply voltage.
[0024]
Similarly to the active wheel speed sensor 17A, the other active wheel speed sensors 17B to 17D can determine the malfunction of the active wheel speed sensors 17B to 17D due to the decrease in the power supply voltage. Connected.
[0025]
The control unit 16 determines the malfunction of the active wheel speed sensors 17A to 17D according to the procedure shown in FIGS. 3 and 4. First, in FIG. 3, in step S1, the detected voltage V, that is, the voltage obtained on the line L2 is obtained. It is determined whether the voltage is equal to or higher than a first set voltage VO1 set in advance. If V <VO1, the process proceeds to step S2. In this step S2, it is determined whether or not the detected voltage V is lower than or equal to the second set voltage VO2. The second set voltage VO2 is lower than the first set voltage VO1 and the active wheel speed sensor It is set as the minimum operating voltage that guarantees the operation of 17A to 17D.
[0026]
When it is determined in the second step S2 that V ≦ VO2, the reset counter is cleared in step S3, and the time TCR of the reset counter is set to “0”. In the next step S4, the time of the voltage drop counter is counted. “1” is added to the time TCD, and the process proceeds to step S5.
[0027]
In step S5, it is determined whether or not the counted time TCD of the voltage drop counter is equal to or longer than a first set time TO1, for example, 100 ms. When TCD ≧ TO1, the voltage drop flag FD is set in step S6, and FD is set. After setting = 1, the process proceeds to step S8. If TCD <TO1, the voltage drop flag FD is reset in step S7, and after FD = 0, the process proceeds to step S8.
[0028]
In step S8, it is determined whether the anti-lock brake control (shown as ABS in FIG. 3) is being performed by operating the hydraulic pressure adjusting means 4, and if it is determined that the vehicle is in the non-anti-lock brake control state, In step S9, it is determined whether or not the braking force distribution control (denoted by EBD in FIG. 3) is being executed. If it is determined that the vehicle is in the non-braking force distribution control state, the sensor indefinite counter is cleared in step S10. After setting the count time TCS of the sensor indefinite counter to “0”, the process proceeds to step S20 in FIG. That is, neither the antilock brake control nor the braking force distribution control is executed, and the sensor indefinite counter is cleared when the hydraulic pressure adjusting means 4 is in the non-operating state.
[0029]
On the other hand, when it is determined in step S8 that the anti-lock brake control is being executed, and when it is determined in step S9 that the non-anti-lock brake control is being performed but the braking force distribution control is being executed, When the pressure adjusting unit 4 is in the operating state, "1" is added to the time TCS of the sensor indefinite counter in step S11, and in the next step S12, the time TCS of the sensor indefinite counter is set to the second set time TO2, for example, 1 second. It is determined whether or not the above has been satisfied. If TCS ≧ TO2, the sensor indefinite flag FS is set in step S12, FS = 1, the process proceeds to step S20 in FIG. 4, and TCS <TO2. In some cases, the process bypasses step S13 and proceeds to step S20.
[0030]
If it is determined in step S2 that the detected voltage V exceeds the second set voltage VO2, the process proceeds to step S14, in which the voltage drop counter, the sensor indefinite counter, and the reset counter are cleared, and TCD = 0, TCS = 0, After setting TCR = 0, the process proceeds to step S20.
[0031]
Further, when it is determined in step S1 that the detection voltage V is equal to or higher than the first set voltage VO1, in step S15, the voltage drop counter and the sensor indefinite counter are cleared, and after TCD = 0 and TCS = 0, In step S16, it is determined whether both the voltage drop flag FD and the sensor indefinite flag FS are "0". If FD = 0 and FS = 0, the process proceeds to step S20. If not, the process proceeds to step S20. Proceed to S17.
[0032]
In step S17, “1” is added to the clock time TCR of the reset counter. In step S18, when it is confirmed that the clock time TCR of the reset counter is equal to or longer than the third set time TO3, for example, 1 second, After resetting the voltage drop flag FD and the sensor indefinite flag FS in S19 and setting FD = 0 and FS = 0, the process proceeds to step S20.
[0033]
In step S20 of FIG. 4, it is determined whether or not the set indefinite flag FS is "1". If it is confirmed that FS = 1, the process proceeds to step S21, and the hydraulic pressure adjusting means 4 is operating. When "1" is added to the counted time TCJB of the diagnostic counter at that time, and it is confirmed in step S22 that the counted time TCJB is equal to or longer than the fifth set time TO5, for example, 1 second, the process proceeds to step S23, and the power supply voltage is reduced. After determining that the active wheel speed sensors 17A to 17D are malfunctioning due to the decrease, the process proceeds to step 25.
[0034]
If FS = 0 in step S20, the diagnostic counter when the hydraulic pressure adjusting means 4 is operating is cleared in step S24, and the counted time TCJB is set to "0", and the process proceeds to step S25.
[0035]
At step S25, it is determined whether or not the voltage drop flag FD is "1". When FD = 1, at step S26, the time of the diagnosis counter when the hydraulic pressure adjusting means 4 is not operating is counted. When "1" is added to the time TCJA, and it is confirmed in step S27 that the counted time TCJA is equal to or longer than the fourth set time TO4, for example, 10 seconds, the process proceeds to step S28, and the active wheel speed sensor is activated due to a decrease in the power supply voltage. 17A to 17D are determined to be malfunctioning.
[0036]
If FD = 0 in step S25, the diagnosis counter when the hydraulic pressure adjusting means 4 is not operating is cleared in step S29, and the time TCJA is set to "0".
[0037]
According to such a determination procedure, when the power supply voltage, that is, the voltage obtained by the line L2 is equal to or lower than the second set voltage VO2 set in advance, and the hydraulic pressure adjusting means 4 is inactive, the second setting is performed. When the state where the voltage is equal to or less than the voltage is equal to or more than the sum of the first and fourth set times TO1 and TO4, and more than 10.1 seconds in this embodiment, the active wheel speed sensors 17A to 17D due to the decrease in the power supply voltage. Is determined to be malfunctioning. On the other hand, when the voltage obtained by the line L2 is equal to or lower than the second set voltage VO2 set in advance, and when the hydraulic pressure regulating means 4 is operating, the first, second and fifth set times TO1, When the time exceeds the sum of TO2 and TO5, that is, 2.1 seconds or more in this embodiment, it is determined that the active wheel speed sensors 17A to 17D are malfunctioning due to a decrease in the power supply voltage.
[0038]
That is, the control unit 16 determines that the state in which the power supply voltage applied to the active wheel speed sensors 17A to 17D drops below the set voltage when the hydraulic pressure adjusting means 4 operates is shorter than when the hydraulic pressure adjusting means 4 is not operating. It is determined that the active wheel speed sensors 17 </ b> A to 17 </ b> D are malfunctioning when the time is maintained.
[0039]
Therefore, when the hydraulic pressure adjusting means is operating to adjust the brake hydraulic pressure of the wheel brake 2A, the state in which the power supply voltage applied to the active wheel speed sensors 17A to 17D has fallen below the set voltage is relatively short. The active wheel speed sensors 17 to 17D are diagnosed to be malfunctioning when they continue, and the malfunctions of the active wheel speed sensors 17 to 17D are promptly determined so that erroneous operation control of the hydraulic pressure adjusting means 4 does not continue. Can be determined.
[0040]
Further, when the hydraulic pressure adjusting means 4 is not operated, the active wheel speed sensors 17A to 17D are determined to be malfunctioning because the state in which the power supply voltage has dropped below the set voltage continues for a relatively long time. It is possible to reliably determine the malfunction of the active wheel speed sensors 17A to 17D due to the decrease in the power supply voltage, even when the power supply voltage temporarily decreases due to the operation or the like.
[0041]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.
[0042]
【The invention's effect】
As described above, according to the present invention, the malfunction of the active wheel speed sensor due to the decrease in the power supply voltage can be determined promptly when the hydraulic pressure adjusting means is operating and reliably when the hydraulic pressure adjusting means is not operating. it can.
[Brief description of the drawings]
FIG. 1 is a diagram showing a hydraulic circuit configuration of a vehicle brake control device.
FIG. 2 is a diagram showing a connection circuit configuration of an active wheel speed sensor and a control unit.
FIG. 3 is a part of a flowchart showing a procedure for determining a malfunction of an active wheel speed sensor.
FIG. 4 is a diagram showing the remaining part of the flowchart showing the procedure for determining the malfunction of the active wheel speed sensor.
[Explanation of symbols]
2A, 2B, 2C, 2D: Wheel brake 4: Hydraulic pressure adjusting means 16: Control units 17A, 17B, 17C, 17D: Active wheel speed sensor

Claims (1)

A fluid pressure regulating means (4) capable of regulating the brake fluid pressure of the wheel brakes (2A, 2B, 2C, 2D); active wheel speed sensors (17A, 17B, 17C, 17D) for detecting wheel speeds; A control unit (16) for controlling operation of the hydraulic pressure adjusting means (4) based on wheel speeds detected by active wheel speed sensors (17A to 17D). (16) The state in which the power supply voltage applied to the active wheel speed sensors (17A to 17D) is reduced to a set voltage or less when the hydraulic pressure adjusting means (4) is activated. ), The active wheel speed sensors (17A to 17D) are determined to be malfunctioning when they last for a shorter time than when they are not operated. .

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