JPH0999835A - Brake warning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a defective brake return by generating an alarm to a driver' s seat when there is no output from a brake detecting circuit detecting the action of a brake while there is an output from an identifying means identifying that the rotation irregularity exceeds the set threshold value. SOLUTION: A program control circuit 4 receives the revolving speeds of wheels from respective rotation sensors and judges whether a stop lamp circuit 2 is turned on or not. If the stop lamp circuit 2 is not turned on, no braking action is taken, and the program control circuit 4 executes brake warning control. The program control circuit 4 identifies whether the rotation irregularity appearing in the outputs of the rotation sensors 1 received by the identifying means of the program control circuit 4 exceeds the set threshold value or not. If the rotation irregularity exceeds the threshold value, the program control circuit 4 sends a warning signal to a warning means and generates an alarm on an indicator 3 provided at a driver's seat. A defective brake return not discernible easily can be detected with high sensitivity.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION The present invention is applied to an automobile. The present invention relates to a device that warns a driver when a vehicle is traveling due to a defective brake return. The present invention relates to a device for preventing a brake fade phenomenon.

The present invention is mainly intended for service brakes, but it is possible to detect a defective return of the parking brake.

[0003]

2. Description of the Related Art Generally, an automobile has two systems of brakes,
Service and parking brakes are provided. For both of these brake systems, the vehicle may not be released or may be inadequately released when the vehicle has not been used for a long period of time, for some other reason, or due to a driver's operation error. It is possible to start. Naturally, the driver should take care to deal with the problem that the brake is not returning properly when the car starts to run, but in order to provide a vehicle that can be driven more safely, the brake release has recently been done. A device that automatically detects defects and issues an alarm to the driver's seat has been installed.

As a conventional example device, an actual Kaihei 6-22144 is used.
The technique disclosed in Japanese Patent Publication is known. This is a device related to the prior application of the applicant of the present application, and is a device for issuing an alarm when the brake oil pressure is still a predetermined value or more when a predetermined time has elapsed after the accelerator pedal is depressed. In addition, JP-A-5
The device disclosed in Japanese Patent Publication No. 42868/1994 electrically detects a temperature change of a brake, superimposes the temperature change on an output of a vehicle speed sensor, and transmits the result to a control circuit.

[0005]

It is generally very rare for a vehicle to run without the brakes being released. Especially, in a vehicle driven by a familiar driver, such an abnormality hardly occurs. Most vehicles will never generate a brake alarm in a practical sense even once during the life of the vehicle. In addition, the fact that the vehicle starts traveling without releasing the brake should be noticed by the driver even if there is no warning, and it is not preferable to rely on the brake warning device to drive the vehicle. Therefore, it is desirable that the brake alarm device be inexpensive.

If a brake alarm device is provided, it is significant unless a slight brake return failure is detected such that a small braking pressure that cannot be noticed by the driver in normal driving conditions remains unreleased. Becomes thin.

On the other hand, in recent years, ABS (Anti-Lock Brake Syst)
em, automatic brake control system) became popular. This device is
When a wheel slips during braking, the rotation error of a plurality of wheels becomes large, and this is detected to control the braking pressure to be temporarily and intermittently relaxed. The wheel of an automobile equipped with this device is provided with a highly accurate rotation sensor. A vehicle equipped with this device is provided with a detection circuit for detecting whether or not the brake is operated as an electric signal. The output of the detection circuit is taken in by the control circuit by the computer. Therefore, if these sensors, detection circuits, and this control circuit are used, the brake alarm device is equipped by simply adding software for the control circuit or by adding a small number of microprocessor semiconductor elements to the control circuit. It will be possible.

The present invention has been made against such a background, and an object thereof is to provide an inexpensive brake warning device. An object of the present invention is to provide a brake warning device that can be installed together with a brake control device (ABS). It is an object of the present invention to equip a practical vehicle with a brake warning device with little or no additional hardware or by adding or modifying software with a small amount of additional hardware. It is an object of the present invention to provide a highly sensitive brake warning device that can detect a brake return failure that the driver cannot easily notice in normal driving conditions.

[0009]

SUMMARY OF THE INVENTION According to the present invention, when a vehicle travels in a state where a brake return failure has occurred, a warning is issued to the driver to detect a brake return failure early and to cause a fade phenomenon. It is characterized by preventing.

That is, according to the present invention, the rotation sensor provided on the wheel provided with the brake detects the rotation of the wheel as an electric signal, and the identification means of the control circuit detects the rotation unevenness appearing in the output of the rotation sensor in advance. Identify whether or not the set threshold is exceeded. Further, the brake detection circuit detects whether or not the brake is operated. If there is an output from the identification means indicating that the rotation unevenness has exceeded the set threshold value, and the output from the brake detection circuit indicates that the brake operation has not been performed, it is assumed that a brake return failure has occurred. An alarm is issued from an alarm means provided in the driver's seat.

As the brake detection circuit, a stop lamp circuit which is turned on when the brake pedal is operated can be used, whereby the presence or absence of the brake operation can be detected without newly installing hardware. .

In order to detect the rotation unevenness of each wheel provided with a brake, it is desirable to provide rotation sensors on all the wheels. When a plurality of rotation sensors are provided, the identification means takes in the outputs of the plurality of rotation sensors, calculates the difference between the outputs generated at predetermined time intervals, and returns the brake when the difference value exceeds the threshold value. It is assumed that uneven rotation occurs due to a defect.

During braking, high frequency vibration due to friction between the brake drum and the brake shoe is transmitted to the sensor ring of the rotation sensor to generate vibration. When the sensor ring vibrates, a high frequency is placed on the output voltage of the rotation sensor. The identifying means can identify the occurrence of uneven rotation by detecting whether or not the output electric signal of the rotation sensor includes a frequency component exceeding the signal frequency generated by the normal running of the vehicle. .

Such a brake alarm device avoids a situation in which the braking pressure is temporarily reduced and a slip state occurs when at least one wheel stops rotating despite the rotation of other wheels. Brake control device (A
BS) can be installed side by side. In this case, the detection of the return failure is performed during the period when the brake pedal is not depressed, and an alarm is immediately issued when it is shown that the brake pedal is in the braking state even though the brake pedal is not depressed. .

Such a device of the present invention can be easily realized in a vehicle equipped with a brake control device by slightly adding hardware or by adding or changing software without adding hardware. Is. This makes it possible to detect with a high sensitivity a small amount of brake return failure that does not release the small braking pressure that cannot be noticed by the driver in normal driving conditions and remains with a high sensitivity without costing much. Can occur.

[0016]

Next, an embodiment of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing the configuration of the first embodiment of the present invention.

The first embodiment of the present invention includes a brake control device (ABS), a rotation sensor 1 for detecting the rotation of a wheel 11 on which a brake is mounted as an electric signal, and a brake detection circuit for detecting a brake operation. Stop lamp circuit 2 and indicator 3 installed in the driver's seat to display an alarm
And a program control circuit 4 for controlling the brake. The program control circuit 4 has an identifying means for identifying that the rotation unevenness appearing in the output of the rotation sensor 1 exceeds a set threshold value, and an indicator when the identifying means has an output and the stop lamp circuit 2 has no output. 3 includes an alarm means for sending an alarm signal, and the exhaust brake switch 5
Output is connected.

The rotation sensor 1 is a plurality of wheels 1 of one vehicle.
As shown in FIG. 2, the sensor ring 1a has a tooth profile on the outer circumference and rotates together with the wheel 11, and a sensor 1b that generates a sinusoidal induced electromotive force by electromagnetic induction.

The brake control device further includes a brake valve 13 which is opened and closed by operating the brake pedal 12, and a control valve 14 which is connected to the brake valve 13 by a fluid line and is opened and closed according to a control signal from the program control circuit 4. , This control valve 14
And a wheel cylinder 15 that is connected by a fluid line to apply a braking force.

Next, the operation of the first embodiment of the present invention thus constructed will be described. FIG. 3 is a flowchart showing the flow of the switching operation between the brake alarm control and the brake control (ABS) in the first embodiment of the present invention.

The program control circuit 4 takes in the rotational speeds of the wheels from the respective rotation sensors 1 and determines whether or not the stop lamp circuit 2 is in the ON state. If the stop lamp circuit 2 is not in the on state, the brake operation is not performed, so the brake alarm control is executed. This control discriminates whether or not the rotation unevenness appearing in the output of the rotation sensor 1 captured by the discriminating means of the program control circuit 4 exceeds a set threshold value, and if it exceeds the threshold value, an alarm signal is sent to the alarm means. Send out. The alarm means issues an alarm to the display device 3 provided in the driver's seat according to this alarm signal.

When the stop lamp circuit 2 is in the ON state, the brake pedal 12 is depressed and the braking operation is being performed, so that the control shifts to the antilock brake control (ABS control). In this ABS control, the speed, acceleration, deceleration, and slip amount (rate) of the wheel 11 are calculated from the detection signal of the rotation sensor 1, and the wheel deceleration or slip amount (rate) exceeds the limit value. At the same time, a control signal is immediately sent to the control valve 14 so that the wheel cylinder 1
5 is operated to adjust an excessive braking pressure. In FIG. 1, the left and right wheels of the front axle are simultaneously controlled, and the left and right wheels of the rear axle are independently controlled.
An example in which the rotation sensor 1 is provided for each of the No. 1 is shown.

The control operation of the first embodiment of the present invention will now be described in detail. FIG. 4 is a flow chart showing the flow of the operation for calculating the correction coefficient required for setting the tire diameter in the first embodiment of the present invention, and FIG. 5 is a flow chart showing the flow of the brake warning control operation in the first embodiment of the present invention. .

First, the tire diameter setting operation will be described with reference to FIG. The program control circuit 4 controls each wheel 11
The pulse signal outputs F ₁ , F ₂ , F ₃ , F ₄ indicating the rotation speed are taken in from the respective rotation sensors 1 provided in the vehicle, and the vehicle speeds v ₁ , v ₂ , v ₃ , v ₄ indicated by the respective wheels 11 are calculated. To do. The calculated vehicle speeds v ₁ , v ₂ , indicated by the respective wheels 11,
It is confirmed whether v ₃ and v ₄ are 10 km / h or less. If it is 10 km / h or less, the average value [outer 1] of the rotation speed indicated by each wheel 11 is calculated by the following equation.

[0026]

[Outside 1]

[0027]

[Equation 1] Next, the coefficients [beta] ₁ , [beta] ₂ , [beta] ₃ , [beta] ₄ required for setting the tire diameter of each wheel are calculated from this average value [outer 1] by the following equation.

[0028]

[Equation 2] The calculated values of the coefficients β ₁ , β ₂ , β ₃ , and β ₄ are stored in the storage circuit.

Next, the main operation of alarm generation will be described with reference to FIG. The program control circuit 4 is for each wheel 1
Incorporating pulse signal outputs F ₁ , F ₂ , F ₃ , F ₄ indicating the rotation speed from the respective rotation sensors 1 provided in 1,
The vehicle speeds v ₁ , v ₂ , v ₃ , and v ₄ of the wheels 11 are calculated.
It is confirmed whether or not each of the calculated vehicle speeds v ₁ , v ₂ , v ₃ , and v ₄ of each wheel exceeds 30 km / h.

The vehicle speed of each wheel 11 is 30 km / h.
If it exceeds, the vehicle is in an accelerating state, so the acceleration α ₁ = dv ₁ / dt and α ₂ = dv ₂ / dt of the front wheels are calculated to avoid erroneous determinations due to tire slip during sudden acceleration / deceleration. Therefore, it is determined whether or not the calculated accelerations α ₁ and α ₂ exceed a preset acceleration setting value α. If it does not exceed the set value α, it is determined that the sudden acceleration / deceleration is not performed, and it is determined whether the stop lamp circuit 2 is in the off state. If the stop lamp circuit 2 indicates that it is in the off state, the brake pedal 12 is not depressed, so it is determined whether the exhaust brake switch 5 is in the off state. If the exhaust brake switch 5 is in the OFF state, braking by the exhaust brake is not being performed, so the correction factors β ₁ , β ₂ , β ₃ , β ₄ stored in the memory circuit in advance are read out and the rotation sensors are read. 1, the number of rotation pulses F ₁ , F ₂ ,
F _3, the calibration value F of _{F 4 '1, F' 2} , F '3, F' 4 a, is calculated by the following equation.

F ′ ₁ == β ₁ F ₁ F ′ ₂ == β ₂ F ₂ F ′ ₃ == β ₃ F ₃ F ′ ₄ == β ₄ F ₄ Then, the average value of the calibrated rotation pulse number [Outer 2] is calculated by the following equation.

[0032]

[Outside 2]

[0033]

(Equation 3) Further, using this average value [outer 2], the difference D (%) of the output of the rotation sensor 1 is calculated by the following equation.

[0034]

[Equation 4] It is determined whether or not the calculated difference D (%) is greater than or equal to a preset setting value.
It is determined whether or not the state has continued for a predetermined time. If it continues for a predetermined time, it is determined that the brake pedal 12 has returned to a defective state, and the alarm means sends an alarm signal to the display device 3 provided in the driver's seat. The display 3 issues an alarm according to this alarm signal.

(Second Embodiment) FIG. 6 is a block diagram showing the configuration of the second embodiment of the present invention.

In the second embodiment of the present invention, the program control circuit 4 in the first embodiment has a rotation sensor 1 as an identification means.
A frequency analysis circuit 6 for detecting whether or not the output electric signal contains a frequency component exceeding the signal frequency generated by the normal traveling speed of the vehicle is provided, and the other parts are configured in the same manner as the first embodiment.

FIG. 7 is a flow chart showing the flow of control operation of the program control circuit in the second embodiment of the present invention. In the case of the second embodiment, the determination operation of the exhaust brake switch 5 is performed in the same manner as in the first embodiment. If the exhaust brake switch 5 is in the off state, the braking by the exhaust brake is not performed, and therefore the frequency analysis of the rotation pulse fetched from each rotation sensor 1 is performed.

FIG. 8 (a) is a diagram showing the waveform of the rotation sensor output during normal running in the second embodiment of the present invention, and FIG. 8 (b) is a diagram showing its frequency analysis. During normal traveling in which no brake return failure has occurred, a sine wave signal as shown in FIG. When the frequency is analyzed, only the frequency within the normal frequency range f _S , for example, f ₁ is detected as shown in FIG. However, when the wheel 11 is in a braking state due to a failure in returning to the brake, as shown in FIG. 9A, a component of high frequency f ₂ that exceeds the normal frequency range f _S caused by braking is generated as shown in FIG. Is transmitted to the sensor ring 1a and the vibration component is applied to the sensor ring 1a in the rotation direction or the opposite direction as in the portions A and B of FIG. When the frequency at that time is analyzed, it appears as a frequency f ₂ exceeding the normal frequency range f _S as shown in FIG.

The frequency f ₁ due to this rotation pulse and the frequency component due to the defective return of the brake are detected and averaged to determine whether or not f ₁ <f ₂ . If f ₂ is greater than f _1, voltages V _1, shown at frequency f _1, the relationship is V ₁ of the voltage V _2, and the voltage V ₃ indicating the noise level is indicated when the frequency f _2> V ₂ > V ₃
Is determined. If this relationship is established, it is considered that there is a drag of the brake, and it is determined whether or not the state has continued for a predetermined time. If it continues for a predetermined time, an alarm signal is sent to the display device 3. The display 3 issues an alarm by this alarm signal and returns to the brake to notify that there is a defect.

(Third Embodiment) FIG. 10 is a block diagram showing the arrangement of the essential parts of a third embodiment of the present invention.

In the third embodiment of the present invention, as shown in the first and second embodiments, instead of taking in the output of the stop lamp circuit 2 and detecting the presence or absence of brake release during the period when the stop lamp is lit, , Is configured to detect whether or not the brake is released while the accelerator pedal 16 is being depressed. An operation similar to that of the first embodiment or the second embodiment is performed, except that it is determined whether or not the brake pedal is depressed based on the presence or absence of the output from the accelerator pedal 16.
Similar effects can be obtained.

[0042]

As described above, according to the present invention, since it can be installed in the existing brake control unit (ABS), it is possible to add the software by adding or changing the software without adding any hardware. In this driving state, it is possible to detect with high sensitivity a brake return defect that the driver cannot easily notice, and it is possible to prevent the occurrence of a brake fade phenomenon.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention.

FIG. 2 is a perspective view showing the configuration of a rotation sensor according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a flow of a switching operation between brake alarm control and brake control (ABS) in the first embodiment of the present invention.

FIG. 4 is a flowchart showing a flow of an operation of calculating a correction coefficient required for setting a tire diameter in the first embodiment of the present invention.

FIG. 5 is a flowchart showing the flow of a brake warning control operation in the first embodiment of the present invention.

FIG. 6 is a block diagram showing the configuration of a second embodiment of the present invention.

FIG. 7 is a flowchart showing a flow of control operation of the program control circuit in the second embodiment of the present invention.

FIG. 8A is a diagram showing a waveform of a rotation sensor output during normal traveling in the second embodiment of the present invention, and FIG. 8B is a diagram showing a frequency analysis thereof.

9A is a diagram showing a waveform of a rotation sensor output when a brake return is defective in the second embodiment of the present invention, and FIG. 9B is a diagram showing a frequency analysis thereof.

FIG. 10 is a block diagram showing a configuration of a main part of a third embodiment of the present invention.

[Explanation of symbols]

 1 rotation sensor 1a sensor ring 1b sensor 2 stop lamp circuit 3 indicator 4 program control circuit 5 exhaust brake switch 6 frequency analysis circuit 11 wheel 12 brake pedal 13 brake valve 14 control valve 15 wheel cylinder 16 accelerator pedal

Claims (5)

[Claims] 1. A rotation sensor for detecting rotation of a wheel provided with a brake as an electric signal, identification means for identifying that rotation unevenness appearing in the output of the rotation sensor exceeds a set threshold value, and brake operation. Brake warning device comprising: a brake detection circuit that detects that the driver is seated and a warning unit that issues a warning to the driver's seat when the identification means has an output and the brake detection circuit has no output. . 2. The brake warning device according to claim 1, wherein the brake detection circuit is a stop lamp circuit that is turned on when a brake pedal is operated. 3. The rotation sensors are provided respectively on a plurality of wheels of one vehicle, and the identifying means takes in the output electrical signals of the plurality of rotation sensors and produces a difference between the plurality of rotation sensor outputs generated at predetermined time intervals. The brake alarm device according to claim 1 or 2, further comprising a means for calculating 4. The brake warning device according to claim 1, wherein the identifying means includes means for detecting that the electric signal includes a frequency component exceeding a signal frequency generated by a normal traveling speed of the vehicle. . 5. A brake control device comprising means for temporarily controlling the braking pressure to be small when at least one wheel stops rotating while the other wheels are rotating. 4. The brake control device according to any one of 4 above, wherein the control of the brake control device is executed while the brake pedal is not depressed.