阅读说明：本技术 一种基于制动灯开关的真空度传感器故障诊断方法 (Vacuum degree sensor fault diagnosis method based on brake lamp switch ) 是由 聂志福 李湾湾 徐益 于 2021-09-13 设计创作，主要内容包括：本发明公开了一种基于制动灯开关的真空度传感器故障诊断方法,通过增加逻辑方法,依据各个时段制动开关的制动踏板信号以及真空度值,进行检测判断,通过真空度值VAC0-VAC1、VAC6-VAC5以及VAC4-VAC3的差值的判断推理,进入到不同的故障处理模式,选择正常启停策略或者本发明的诊断方法的故障处理模式。这种方法解决了关于真空度传感器因为内部元器件故障使输出值无变化,导致真空泵停止工作而出现刹车无助力的问题,不仅能识别出此故障,还能进入故障处理模式,保证真空泵正常工作,提供刹车所需真空源。(The invention discloses a vacuum degree sensor fault diagnosis method based on a brake lamp switch, which comprises the steps of adding a logic method, carrying out detection and judgment according to brake pedal signals and vacuum degree values of the brake switch at each time interval, entering different fault treatment modes through judgment and inference of difference values of the vacuum degree values VAC0-VAC1, VAC6-VAC5 and VAC4-VAC3, and selecting a normal start-stop strategy or the fault treatment mode of the diagnosis method. The method solves the problem that the vacuum pump stops working and the brake has no power assistance because the output value of the vacuum degree sensor is unchanged due to the fault of the internal components, can not only identify the fault, but also enter a fault processing mode, ensure the normal work of the vacuum pump and provide a vacuum source required by the brake.)

1. A vacuum degree sensor fault diagnosis method based on a brake lamp switch is characterized by comprising the following steps:

s1, turning on an ignition switch of the whole vehicle, changing a brake pedal signal B of a brake lamp switch from 0 to 1, and recording a vacuum value VAC0 of a first preset time before triggering if a vacuum pump does not work in the process; after the first preset time, the vacuum pump still does not work, and the current vacuum value VAC1 is recorded;

s2, judging whether VAC0-VAC1 is larger than 1, if yes, executing according to a normal start-stop strategy; if not, starting the vacuum pump and transferring to the step S3;

s3, if B =1, the vacuum pump starts working and records a vacuum value VAC5 when the pump just starts working, after the working lasts for the maximum second preset time, the vacuum value VAC6 is recorded, whether VAC6-VAC5 is larger than 3 is judged, if yes, the pump is in accordance with a normal start-stop strategy, wherein when the difference value is larger than 3 and the threshold value reaches more than 70 within the second preset time, the pump stops working in advance and then is in accordance with the normal start-stop strategy; if not, the pump continuously works for a second preset time, the VAC5 and the VAC6 values are updated for re-judgment, and if the period B =0, the step S4 is carried out;

s4, if B =0, recording the current vacuum value VAC3, stopping the pump after the pump continuously works for a second preset time, recording the current vacuum value VAC4 and turning to the step S5, and if B is changed into 1 within the second preset time, turning to the step S3;

s5, when VAC4-VAC3 is larger than 1, judging whether the counter XC is 0, if so, executing the vacuum pump according to a normal start-stop strategy, otherwise, executing XC-1 by the counter XC, and turning to the step S3; when VAC4-VAC3 is less than or equal to 1, counter XC performs XC +1 and proceeds to step S6;

s6, judging whether XC is equal to 1, if XC is equal to 1, then switching to S4, and if XC is not equal to 1, switching to S7;

and S7, if XC =2, displaying a brake system fault alarm identifier by the instrument, recording a fault code as a vacuum degree sensor fault, and subsequently repeatedly executing the steps S3 to S4 until the whole vehicle is restarted, and setting the XC count to be 0.

2. The brake lamp switch-based vacuum degree sensor fault diagnosis method as claimed in claim 1, wherein the brake lamp switch controls whether a brake pedal is pressed, and when B =0, the brake pedal is not pressed, and when B =1, the brake pedal is pressed.

3. The brake lamp switch-based vacuum degree sensor fault diagnosis method as claimed in claim 1, wherein the normal start-stop strategy is executed according to the following main logic:

the control process is circulated every 20 ms;

when the vacuum degree is lower than a vacuum pump starting threshold VACON, starting the vacuum pump;

when the vacuum degree is higher than a vacuum pump cut-off threshold value VACOFF, the vacuum pump is closed;

if the output vacuum value is always higher than VACon due to the fault of the vacuum degree sensor, the pump does not start to work actively, and therefore vacuum is continuously consumed in the braking process, and no assistance is gradually generated.

4. The vacuum degree sensor fault diagnosis method based on the brake lamp switch as claimed in claim 1, wherein if the time before triggering does not reach the first preset time in the step S1, recording the time as the closest to the first preset time.

5. The brake lamp switch-based vacuum degree sensor fault diagnosis method as claimed in claim 1, wherein in the step S1, if the brake lamp switch B is repeatedly detected to be converted from 0 to 1 within a first preset time, the VAC0 is not updated.

6. The brake lamp switch-based vacuum degree sensor fault diagnosis method as claimed in claim 1, wherein the judgment of VAC6-VAC5 in the step S3 is made every 1S for the second preset time.

7. The brake lamp switch-based vacuum degree sensor fault diagnosis method as claimed in claim 1, wherein the first preset time is 1s, the second preset time is 10s, and the vacuum degree value is an absolute value of a difference between atmospheric pressure and internal pressure of a test object.

Technical Field

The invention relates to the technical field of automobile vacuum systems, in particular to a vacuum degree sensor fault diagnosis method based on a brake lamp switch.

Background

In order to effectively save non-reusable energy, development and utilization of new energy technology are increasingly prominent, in which new energy vehicles are heavily designed and developed as representatives of energy consumption. Whether the brake vacuum booster can maintain a certain vacuum degree in real time when the vehicle brakes enables a driver to smoothly step on the brake vehicle, and the brake vacuum booster has great significance for safe driving of the vehicle. However, the vacuum degree of the brake vacuum booster of the electric automobile is completely from the electric vacuum pump, and whether the electric vacuum pump works or not is mainly determined by the vacuum degree in the brake vacuum booster measured by the vacuum degree sensor. Therefore, whether the vacuum degree sensor can accurately measure the vacuum degree in the brake vacuum booster or not has great significance for ensuring the reliable working durability and the brake safety of the electric vacuum pump. At present, most new energy passenger vehicles still use the traditional vacuum booster system, a vacuum pump is needed to provide a vacuum source for a vacuum booster, whether the vacuum pump works or not needs a corresponding control method, and in addition, diagnosis needs to be provided aiming at whether system hardware has a fault or not, so that the pump still works under the fault state of other hardware except the vacuum pump, and the brake safety is ensured.

For example, the present invention discloses a vacuum assist system and a vehicle having the same, which are disclosed in chinese patent literature and have a publication number of "CN 106004848A", and the present invention discloses a vacuum assist system and a vehicle having the same, the vacuum assist system including: the three-way pipe comprises a first port, a second port and a third port; a vacuum booster connected to the first port; a vacuum pump; the vacuum pump and the engine vacuum source are connected with the second port through the vacuum pipe; a vacuum degree sensor; and the vacuum degree sensor is arranged on the sensor support and is connected with the third port through the sensor support. According to the vacuum boosting system, the vacuum pump and the engine vacuum source are arranged on the same side, and the vacuum degree sensor is arranged on the opposite side, so that the vacuum degree in the vacuum boosting system can be quickly supplemented, the vacuum boosting system occupies a smaller arrangement space, the consumed pipeline is shorter, the vacuum boosting system has fewer fault points, the work is more stable, and the optimization of the arrangement and the man-machine operability of the whole vehicle is facilitated. But no reference is made to a diagnostic method based on a vacuum sensor.

Disclosure of Invention

The invention provides a brake lamp switch-based vacuum degree sensor fault diagnosis method, aiming at solving the problem that the vacuum degree sensor has no power assistance when a vacuum pump stops working due to no change of an output value caused by the fault of an internal component, and the method carries out judgment and comparison according to a brake pedal signal and a vacuum degree value of a brake switch in each time period by adding a logic method and enters different fault processing modes. The method can not only identify the fault, but also enter a fault processing mode to ensure that the vacuum pump works normally and provide a vacuum source required by braking.

In order to achieve the purpose, the invention adopts the following technical scheme: a vacuum degree sensor fault diagnosis method based on a brake lamp switch is characterized by comprising the following steps:

s1, turning on an ignition switch of the whole vehicle, changing a brake pedal signal B of a brake lamp switch from 0 to 1, and recording a vacuum value VAC0 of a first preset time before triggering if a vacuum pump does not work in the process; after the first preset time, the vacuum pump still does not work, and the current vacuum value VAC1 is recorded;

s2, judging whether VAC0-VAC1 is larger than 1, if yes, executing according to a normal start-stop strategy; if not, starting the vacuum pump and transferring to the step S3;

s3, if B is 1, the vacuum pump starts to work and records a vacuum value VAC5 when the pump just starts to work, after the pump works for the maximum second preset time, the vacuum value VAC6 is recorded, whether VAC6-VAC5 is larger than 3 is judged, if yes, the pump is in a normal start-stop strategy, wherein when the difference value is larger than 3 and the threshold value reaches more than 70 within the second preset time, the pump stops working in advance and then is in a normal start-stop strategy; if not, the pump continuously works for a second preset time, the VAC5 and the VAC6 values are updated for re-judgment, and if the period B is equal to 0, the step S4 is carried out;

s4, if B is equal to 0, recording the current vacuum value VAC3, stopping the pump after the pump continuously works for a second preset time, recording the current vacuum value VAC4 and turning to S5, and if B is changed into 1 within the second preset time, turning to S3;

s5, when VAC4-VAC3 is larger than 1, judging whether the counter XC is 0, if so, executing the vacuum pump according to a normal start-stop strategy, otherwise, executing XC-1 by the counter XC, and turning to the step S3; when VAC4-VAC3 is less than or equal to 1, counter XC performs XC +1 and proceeds to step S6;

s6, judging whether XC is equal to 1, if XC is equal to 1, then switching to S4, and if XC is not equal to 1, switching to S7;

and S7, if XC is 2, displaying a brake system fault alarm identifier by the instrument, recording a fault code as a vacuum degree sensor fault, and subsequently repeatedly executing the steps S3 to S4 until the whole vehicle is restarted, and setting XC to be 0. The invention aims at the problem that the vacuum pump stops working due to the fact that the output value of a vacuum degree sensor is unchanged due to the fault of an internal component, so that the brake is not assisted, judgment and comparison are carried out according to the brake pedal signal of the brake switch at each time interval and the vacuum degree value by adding a logic method, different fault processing modes are entered, the pump still works under the fault state of other hardware except the vacuum pump, and the brake safety is ensured. The conventional vacuum pump control method does not diagnose the fault that the output value is unchanged due to the fault of the internal components of the vacuum degree sensor, the normal starting and stopping of the pump are executed according to a normal starting and stopping strategy, and if the output value is always higher than VACon due to the fault of the vacuum degree sensor, the pump cannot actively start working, so that the vacuum is continuously consumed in the braking process, and the booster is gradually lost.

Preferably, the stop lamp switch controls whether or not the brake pedal is depressed, and when B is 0, the brake pedal is not depressed, and when B is 1, the brake pedal is depressed. The brake pedal signal B can accurately represent both states of the brake pedal.

Preferably, the normal start-stop strategy is executed according to the following main logic:

the control process is circulated every 20 ms;

when the vacuum degree is lower than a vacuum pump starting threshold VACON, starting the vacuum pump;

when the vacuum degree is higher than a vacuum pump cut-off threshold value VACOFF, the vacuum pump is closed;

if the output vacuum value is always higher than VACon due to the fault of the vacuum degree sensor, the pump cannot actively start to work, so that the vacuum is continuously consumed in the braking process, and the booster is gradually lost. And the dynamic threshold value of the on-off control of the vacuum pump is determined according to the vehicle speed and the brake pedal signal B.

Preferably, in step S1, if the time before triggering does not reach the first preset time, the recording is performed on the principle that the time duration is closest to the first preset time duration.

Preferably, in step S1, if the stop lamp switch B is repeatedly detected to be shifted from 0 to 1 within the first preset time, the VAC0 is not updated.

Preferably, the step S3 is performed every 1S for the second preset time with respect to VAC6-VAC 5. And the data are judged for many times, so that the data are prevented from being accidental.

Preferably, the first preset time is 1s, the second preset time is 10s, and the vacuum value is an absolute value of a difference between atmospheric pressure and internal pressure of the test object. The first preset time and the second preset time can be adjusted according to actual conditions.

Therefore, the invention has the following beneficial effects:

1. the diagnosis method of the invention provides a vacuum degree sensor fault diagnosis method based on a brake lamp switch, which judges and compares the brake pedal signals and the vacuum degree values according to the brake pedal signals and the vacuum degree values of the brake switch at each time interval by adding a logic method, enters different fault processing modes, can identify the fault, can enter the fault processing mode, ensures the normal work of a vacuum pump and provides a vacuum source required by braking;

2. the diagnosis method of the invention reminds the driver after identifying the fault, thereby ensuring the driving safety.

Detailed Description

Examples

The embodiment provides a ring main unit cable joint fault detection method based on a temperature-sound mixing method, which comprises the following steps:

s1, turning on an ignition switch of the whole vehicle, changing a brake pedal signal B of a brake lamp switch from 0 to 1, and recording a vacuum value VAC0 of a first preset time before triggering if a vacuum pump does not work in the process; after the first preset time, the vacuum pump still does not work, and the current vacuum value VAC1 is recorded;

s2, judging whether VAC0-VAC1 is larger than 1, if yes, executing according to a normal start-stop strategy; if not, starting the vacuum pump and transferring to the step S3;

s3, if B is 1, the vacuum pump starts to work and records a vacuum value VAC5 when the pump just starts to work, after the pump works for the maximum second preset time, the vacuum value VAC6 is recorded, whether VAC6-VAC5 is larger than 3 is judged, if yes, the pump is in a normal start-stop strategy, wherein when the difference value is larger than 3 and the threshold value reaches more than 70 within the second preset time, the pump stops working in advance and then is in a normal start-stop strategy; if not, the pump continuously works for a second preset time, the VAC5 and the VAC6 values are updated for re-judgment, and if the period B is equal to 0, the step S4 is carried out;

s4, if B is equal to 0, recording the current vacuum value VAC3, stopping the pump after the pump continuously works for a second preset time, recording the current vacuum value VAC4 and turning to S5, and if B is changed into 1 within the second preset time, turning to S3;

s5, when VAC4-VAC3 is larger than 1, judging whether the counter XC is 0, if so, executing the vacuum pump according to a normal start-stop strategy, otherwise, executing XC-1 by the counter XC, and turning to the step S3; when VAC4-VAC3 is less than or equal to 1, counter XC performs XC +1 and proceeds to step S6;

s6, judging whether XC is equal to 1, if XC is equal to 1, then switching to S4, and if XC is not equal to 1, switching to S7;

and S7, if XC is 2, displaying a brake system fault alarm identifier by the instrument, recording a fault code as a vacuum degree sensor fault, and subsequently repeatedly executing the steps S3 to S4 until the whole vehicle is restarted, and setting XC to be 0.

And executing the normal start-stop strategy according to the main logic, circulating every 20ms in the control process, starting the vacuum pump when the vacuum degree value is lower than a vacuum pump start threshold VACON, and closing the vacuum pump when the vacuum degree is higher than a vacuum pump shut-off threshold VACOFF. If the output vacuum value is always higher than VACon due to the fault of the vacuum degree sensor, the pump does not start to work actively, and therefore vacuum is continuously consumed in the braking process, and no assistance is gradually generated. After the vacuum degree sensor fault diagnosis method is used, the fault can be identified through logic, and a fault processing mode can be entered, so that the vacuum pump can work normally. And the dynamic threshold value of the vacuum pump on-off control is determined according to the vehicle speed and the brake pedal signal B, and the specific table 1 can be seen.

TABLE 1 dynamic threshold for vacuum pump on-off control under different vehicle speeds and brake pedal signals

1	2	3	4
				V≤30&B＝0	V≤30&B＝1	V>30&B＝0	V>30&B＝1
VACON＝0.6P	VACON＝0.5P	VACON＝0.7P	VACON＝0.6P
				VACOFF＝0.7P	VACOFF＝0.7P	VACOFF＝0.8P	VACOFF＝0.8P

If the vehicle speed reaches more than 30 and drops below 30, the vacuum pump is turned on and is turned off according to the vehicle speed vacuum threshold value of more than 30.

If the time before triggering does not reach 1S in step S1, the vacuum level value is recorded on the basis of the time length closest to 1S, and if the transition of the brake pedal signal B of the stop lamp switch from 0 to 1 is repeatedly detected within 1S, VAC0 is not updated. In step S3, the judgment about VAC6-VAC5 is carried out once every 1S within 10S, so that the accuracy of the data is ensured.

The invention provides a fault recognition method aiming at no change of an output value caused by the fault of an internal component of a vacuum degree sensor, which judges and compares the signals according to the brake pedal signal of a brake switch and the vacuum degree value in each time period by adding a logic method, and enters different fault processing modes, so that the fault can be recognized, the fault processing mode can be entered, the normal work of a vacuum pump is ensured, and a vacuum source required by braking is provided.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.