JPH04232154A - Failure detection method for brake operation sensor - Google Patents

Abstract

PURPOSE:To provide a method of detecting failure of sensor for detecting operation quantity of such as stroke as well as operation force of a brake operation member at the time of non-braking operation, in an electrically controlling brake device. CONSTITUTION:In an electrically controlling brake device, if the stepping force and the stroke value thereof detected by a stepping force sensor 80 and a stroke sensor 82 at a same time during operation of a brake pedal 10 do not satisfy specified conditions respectively, at least one of the sensors 80 or 82 is judged that it has failed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting sensor failure in a brake system.

0002

[Prior Art] Conventionally, a brake device for decelerating and stopping an automobile generates hydraulic pressure in a master cylinder by operating a brake operating member such as a brake pedal.
A hydraulic brake device is used that uses the hydraulic pressure to operate a wheel cylinder and press a friction member against a rotating body. However, in recent years, electrically controlled brakes have been proposed that electrically detect the operating force of a brake operating member and generate a braking force commensurate with the detected result. For example, Japanese Patent Application Laid-Open No. 63-242764 describes a device that presses a brake pad against a brake disc electrically instead of hydraulically. This electrically controlled brake device includes (a) an electric means for bringing the brake pad into contact with and separating from the brake disc by changing the driving direction;
(b) switching means for switching the driving direction of the electric transmission means; (c) detection means for detecting the depression force of the brake pedal; (d) detection means for detecting the brake reaction force generated on the brake pad; ) A controller that compares the detected brake pedal depression force and the brake reaction force, determines the driving direction of the first electric means, and switches the first half switching means.

0003

[Problem to be Solved by the Invention] The above publication describes a sensor that electrically detects the operating force of the brake pedal as a brake operating member, but does not describe anything about detecting failure of the sensor. do not have. However, when electrically controlled brake control devices are actually used, detection of failure of sensors that detect brake operation amounts such as operation force and stroke becomes an important problem. This situation does not change even in an electrically controlled brake device in which the friction member presses the rotating body using hydraulic pressure, and the hydraulic pressure is controlled based on electrical detection of the operation amount.

The present invention has been made against the background of the above-mentioned circumstances and has as an object to provide a method for detecting sensor failure of a brake device.

[0005]

[Means for Solving the Problems] The gist of the present invention is to provide a value obtained by converting a plurality of types of operation amounts detected by a plurality of types of operation amount sensors at the same point in time during operation of a brake operating member into one type of operation amount. The purpose is to determine that at least one of the plurality of types of operation amount sensors has failed if the difference between them is outside the set range.

[0006]

[Effect] Brake operating member operating force, operating stroke,
Master cylinder pressure etc. increase correspondingly. Therefore, if the difference between the values obtained by converting these multiple types of operation amounts detected at the same time during the operation of the brake operation member into one type of operation amount is outside the setting range, the operation force sensor and stroke sensor At least one of them has failed.

[0007] The above-mentioned "value converted from multiple types of manipulated variables into one type of manipulated variable" is, for example, when the manipulated variables are a stroke and an operating force, and the output value of the stroke sensor is converted into a computer or analog circuit. This includes not only values actually converted into operating force values, but also values of operating force planned for a given stroke value. Furthermore, the determination as to whether or not it is outside the set range may be performed continuously or only at one specific point in time or multiple points in time.

[0008]

According to the present invention, a failure of an operation amount sensor in a brake device can be easily and quickly detected. In addition, in order to detect failures by detecting the amount of operation of multiple types of brake operation members, it is possible to determine whether or not the difference between them is outside the set range at the beginning of the brake operation. This has the unique advantage that emergency measures such as operating a mechanically operated manual brake in response to the operating force of the brake operating member can be carried out without delay.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. In FIG. 1, a brake pedal 10 as a brake operating member is connected to a master cylinder 12, and hydraulic pressure corresponding to the depression force of the brake pedal 10 is generated in the master cylinder 12. Master cylinder 1
2 is connected to a two-position solenoid valve 16 by a liquid passage 14, and is also connected to a reservoir 20 by a liquid passage 18. In the original position, the two-position solenoid valve 16 connects the liquid passage 14 and the liquid passage 21 and blocks the stroke simulator 22, but when the solenoid is energized, it blocks the liquid passage 21 and connects the master cylinder 12. is switched to a state where it is communicated with the stroke simulator 22. The stroke simulator 22 accommodates the brake fluid discharged from the master cylinder 12, allows the brake pedal 10 to be depressed, and provides the brake pedal 10 with a reaction force corresponding to the depression stroke. The liquid passage 21 is branched into a liquid passage 24 and a liquid passage 25, and the liquid passage 25 is provided with a proportion valve 23.

The liquid passage 24 and the liquid passage 25 each have two
It is branched at the crotch, and one two-position solenoid valve 26, 28 is disposed at each branch. 2 position solenoid valve 2
6 connects the master cylinder 12 and the front wheel cylinder 30 in the original position, and when the solenoid is energized, the hydraulic control valve 32 and the front wheel cylinder 30 communicate with each other.
communicate with. Similarly, the 2-position solenoid valve 28 connects the master cylinder 12 and the rear wheel cylinder 34 in its original position, and when the solenoid is energized, the hydraulic control valve 36
and the rear wheel cylinder 34.

The reservoir 20, the pump 38 and the accumulator 40 are connected to each other by a liquid passage 42, and the liquid in the reservoir 20 is pumped up by the pump 38 and stored in the accumulator 40 at a certain range of liquid pressure. The hydraulic pressure control valve 32 is connected to the accumulator 40, the front wheel cylinder 30, and the reservoir 20 through a liquid passage 42, a liquid passage 44, and a liquid passage 46, and controls the hydraulic pressure of the front wheel cylinder 30 by controlling the excitation current of the solenoid. The height is controlled to correspond to the magnitude of the excitation current. The hydraulic pressure control valve 36 is also similar, and includes an accumulator 40, a rear wheel cylinder 34, and a reservoir 2.
0 through a liquid passage 42, a liquid passage 48, and a liquid passage 46.

FIG. 2 shows an enlarged view of the vicinity of the brake pedal 10. The brake pedal 10 is rotatably attached to a bracket 50 by a support shaft 52. Further, a spring 54 is stretched between an arm portion 56 of the brake pedal 10 and the bracket 50, and is engaged with a pin 58 on the arm portion 56 side and a support member (not shown) on the bracket 50 side, and The pedal 10 is biased counterclockwise. As a result, brake pedal 1
0 is always in contact with the brake switch 62 via the cushion material 60 and is kept at the original position. The brake switch 62 also functions as a stopper. The brake switch 62 includes a rod 66, a spring 68, and a contact 70, as shown in FIGS. 3 and 4. rod 66
is in contact with the cushioning material 60 and compressing the spring 68, the contacts 70 are separated from each other and the brake switch is in the OFF state, and the cushioning material 60 is separated and the rod 66 is pushed out by the spring 68. In this case, the contacts 70 come into contact with each other and turn on.

The pin 58 connects one end of a booster rod 74 to the brake pedal 10, and the other end of the booster rod 74 extends to a booster 76 and is engaged with a reaction piston (not shown). Further, a load cell type pedal force detection device 80 as a pedal force sensor is disposed on the booster rod 74. The load cell type pedal force detection device 80 detects the compressive force of the booster rod 74 that is generated when the pedal portion 81 is depressed.

A stroke sensor 82 is provided near the pedal force sensor 80. Stroke sensor body 84
A flange 86 is fixed to a flange 83 attached to the bracket 50. One end of the rod 88 of the stroke sensor 82 is in contact with an L-shaped protrusion 89 provided on the arm portion 56, and the other end is fixed to a slider mount 90 as shown in FIG. There is. The slider fitting 90 is generally rectangular in shape and has a full rectangular groove at the bottom, with an end wall 92 of the rectangular groove and a body 84.
A spring 94 is disposed between the two. A slider 96 is attached to the slider mount 90, and the slider 96 moves the resistor 97 by the same distance as the displacement of the rod 88.
It is designed to slide on the top. The resistor 97 is connected to a processing circuit (not shown) by a lead wire bundle 98,
A constant voltage is applied across the resistor 97, and
The voltage between the contact between the slider 96 and the resistor 97 and one end of the resistor 97 can be detected. Thereby, the sliding distance of the slider 96 on the resistor 97 is detected, and the amount of displacement of the rod 88 is detected.

This brake device is controlled by a control device 100. The control device 100 includes a CPU 101 and a RAM 1.
02, ROM 103, input section 104, output section 105, and bus. The brake switch 62, the pedal force sensor 80 and the stroke sensor 82, the hydraulic pressure sensor 110 that detects the hydraulic pressure of the master cylinder 12, the hydraulic pressure sensor 112 that detects the hydraulic pressure of the accumulator 40, and the hydraulic pressure of the wheel cylinders 30 and 34. hydraulic pressure sensor 114
, 115 , wheel speed sensors 117 and 118 that detect the rotational speeds of the front and rear wheels, and a longitudinal G sensor 120 that detects the longitudinal acceleration of the vehicle body are connected to the input section 104 of the control device 100 and output to the output section 105. is the hydraulic pressure control valve 32
, 36 and two-position solenoid valves 16, 26, 28 are connected. Various programs are stored in the ROM 103 of the control device 100, and one of them is a fail detection program for the pedal force sensor 80 and the stroke sensor 82, which is shown in the flowchart of FIG.

In the brake system constructed as described above, while the key switch of the automobile is in the OFF state, the
Position solenoid valves 16, 26, 28 are in the position shown in FIG.
It is in communication with 34. When the key switch is turned on, the two-position solenoid valves 16, 26, 28 are switched, and the master cylinder 12 is communicated with the stroke simulator 22, while the accumulator 40 is communicated with the wheel cylinders 30, 34. Therefore, when the brake pedal 10 is depressed, the stroke simulator 22 applies a reaction force to the brake pedal 10 according to the depression stroke. Furthermore, the elastic force of the spring 54 also increases. Therefore, as the depression stroke of the brake pedal 10 increases, the depression force increases, and the output voltage of the depression force sensor increases as shown in FIG. This output voltage is supplied to the control device 100, which controls the front and rear G sensor 12.
The hydraulic pressure control valves 32 and 36
The hydraulic pressure in the wheel cylinders 30, 34 is controlled via the hydraulic pressure in the wheel cylinders 30, 34. Therefore, the vehicle is braked at a deceleration that is commensurate with the force applied to the brake pedal 10, regardless of the slope of the road, the load, the coefficient of friction of the brake pads, etc. This is the electrical control mode, and the brake system normally operates in this mode.

However, if a failure occurs in the pedal force sensor 80 serving as the operation amount sensor, operation in the electrical control mode becomes impossible, so the present brake system is designed to automatically switch to the manual mode. Therefore, while the key switch is in the ON state, the program shown in FIG. 7 is repeatedly executed at minute intervals along with other programs (not shown).

First, in step 1 (hereinafter simply referred to as S1; the same applies to other steps), the pedal force f of the brake pedal 10 detected by the pedal force sensor 80 is read, and in S2, the pedal force f of the brake pedal 10 detected by the pedal force sensor 80 is read. The detected stroke s of the brake pedal 10 is read. In S3, it is determined whether the value of the pedal force f is 0 kgf or less, and if the determination is YES, it is further determined in S4 whether the value of the stroke s is 8 mm or more, and if the determination is YES, It is determined that at least one of the pedal force sensor 80 and the stroke sensor 82 has failed, and the manual mode is set in S6. Accordingly, the two-position electronic valves 16, 26, and 28 are switched to their original positions in FIG. Braking is performed. On the other hand, in S3, the value of the pedal force f is 0 kgf or more and the determination is NO, and further in S5, it is determined whether the stroke s is 8 mm or more, and if it is determined to be NO, it is also a fail. manual mode is set in S6. If the determination is YES in S5, the sensor is normal, so the above-mentioned electrical control mode is set in S7. Although it is possible to determine that the sensor is normal when the determination is NO in S4, in this embodiment, neither failure nor normality is determined.

Another embodiment of the invention is shown in FIG. Although a detailed explanation of the flowchart will be omitted, in this embodiment, when the pedal force f is 0 kgf or less and the stroke is 8 mm or more, and it is determined as YES in both S13 and S14, the pedal force sensor 80 and the stroke sensor 8
It is assumed that at least one of 2 and 2 has failed.

Still another embodiment of the present invention is shown in FIG. A detailed explanation of the flowchart will be omitted since it is similar to FIG. 7, but in the above embodiment, it is determined whether the output voltage values of the pedal force sensor 80 and the stroke sensor 82 each satisfy a predetermined condition. In contrast, in this embodiment, the output voltage of the pedal force sensor 80 and the output voltage of the hydraulic pressure sensor 110 that detects the master cylinder hydraulic pressure each satisfy a predetermined condition. This is to determine whether the sensor is failing or not.

In the embodiment described above, a linear potentiometer was used as the stroke sensor 82, but a rotary potentiometer, resolver, etc. that detects the stroke by measuring the rotation angle of the brake pedal may be used to rotate the brake pedal. It may be disposed on a support device that supports the

It is also possible to provide a plurality of switches that are turned ON in sequence each time the brake pedal 10 is operated a predetermined stroke, or to attach a slit plate and a photoelectric switch to one brake pedal 10 and the other to a pedal support member. A pulse signal is output from a photoelectric switch every time the brake pedal 10 rotates by a predetermined angle, and the output values of the pedal force sensor 80 and the stroke sensor 82, or the pedal force sensor 80 and the hydraulic pressure sensor 110 at a plurality of points in time are output. It is also possible to detect the failure of these sensors from non-conformity.

Further, each time the output value of the stroke sensor 82 reaches a determination value (which may be a plurality of values), the pedal force sensor 8
In addition to determining the appropriateness of the output value of 0, the pedal force sensor 80
Each time the output value of reaches a predetermined value, the stroke sensor 82
The sensor failure detection time point may be determined based on the output values of a plurality of types of manipulated variable sensors themselves, such as determining the suitability of the output values of the sensor. In this way, a failure can be detected as long as a plurality of types of operation amount sensors do not fail at the same time.

In addition, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an electrically controlled brake device in which sensor failure is detected by a fail detection method that is an embodiment of the present invention.

FIG. 2 is a front view showing a brake switch, a pedal force sensor, a stroke sensor, and a brake pedal in the above embodiment.

FIG. 3 is a front sectional view showing a state in which the brake switch of the above embodiment is OFF.

FIG. 4 is a front sectional view showing a state in which the brake switch of the above embodiment is ON.

FIG. 5 is a front sectional view of the stroke sensor of the above embodiment.

FIG. 6 is a graph showing the relationship between the stroke of the brake pedal and the output voltage of the pedal force sensor under normal conditions.

FIG. 7 is a flowchart showing one of the programs stored in the control device of FIG. 1;

FIG. 8 is a flowchart showing a program of another embodiment of the present invention.

FIG. 9 is a flowchart showing a program of still another embodiment of the present invention.

[Explanation of symbols]

10 Brake pedal 56 Arm part 62 Brake switch 80 Pedal force sensor 82 Stroke sensor 88 Rod 94 Spring 96 Slider 97 Resistor 98 Lead wire bundle 100 Control device 110 Liquid pressure sensor

Claims (1)

[Claims] [Claim 1] The difference between the values obtained by converting the plurality of types of operation amounts detected by the plurality of types of operation amount sensors at the same time during the operation of the brake operating member into one type of operation amount is outside the setting range. A sensor failure detection method for a brake device, in which at least one of a plurality of types of operation amount sensors has failed.