CN114791726A - EGR fault diagnosis method and system and vehicle - Google Patents

EGR fault diagnosis method and system and vehicle Download PDF

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Publication number
CN114791726A
CN114791726A CN202110720286.0A CN202110720286A CN114791726A CN 114791726 A CN114791726 A CN 114791726A CN 202110720286 A CN202110720286 A CN 202110720286A CN 114791726 A CN114791726 A CN 114791726A
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China
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egr valve
pressure value
preset
temperature
gas
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裴俊杨
刘云辉
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Great Wall Motor Co Ltd
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Great Wall Motor Co Ltd
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B23/00—Testing or monitoring of control systems or parts thereof
    • G05B23/02—Electric testing or monitoring
    • G05B23/0205—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults
    • G05B23/0218—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults characterised by the fault detection method dealing with either existing or incipient faults
    • G05B23/0221—Preprocessing measurements, e.g. data collection rate adjustment; Standardization of measurements; Time series or signal analysis, e.g. frequency analysis or wavelets; Trustworthiness of measurements; Indexes therefor; Measurements using easily measured parameters to estimate parameters difficult to measure; Virtual sensor creation; De-noising; Sensor fusion; Unconventional preprocessing inherently present in specific fault detection methods like PCA-based methods

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Exhaust-Gas Circulating Devices (AREA)

Abstract

The invention provides a method, a system and a vehicle for EGR fault diagnosis, wherein the method comprises the following steps: periodically detecting the pressure value of the gas at the rear end of the EGR valve; determining the relation between the pressure value of the gas at the rear end of the EGR valve in the current period and a preset pressure value, and accordingly, monitoring the temperature of the EGR valve end in the current period for a preset time length to determine the relation between the temperature increment and the preset increment of the temperature of the EGR valve end in the preset time length in the current period; and when the pressure value of the gas at the rear end of the EGR valve in the current period is detected to be continuously larger than or equal to the preset pressure value and the temperature increment of the temperature of the EGR valve end in the preset time exceeds the preset increment, outputting alarm information. The method aims to solve the problems that the existing high-flow fault diagnosis scheme based on the EGR valve front temperature has poor anti-interference capability and is easy to generate missed reports or false reports, and meanwhile, the additional auxiliary diagnosis preparation is added in the application, so that the diagnosis cost is increased.

Description

EGR fault diagnosis method and system and vehicle
Technical Field
The invention relates to the technical field of vehicle engineering, in particular to a method and a system for EGR fault diagnosis and a vehicle.
Background
Exhaust Gas Recirculation (EGR), which is short for EGR, is a process in which a small portion of Exhaust Gas generated by a diesel engine or a gasoline engine is returned to a cylinder for combustion, and the improvement of the Exhaust Gas Recirculation rate reduces the total Exhaust Gas flow, so that the total output of pollutants in Exhaust Gas emission is relatively reduced.
Emission regulations require that engines equipped with exhaust gas recirculation systems must be equipped with fault diagnosis of excessive EGR flow. In the scheme of carrying out high-flow fault diagnosis on EGR based on the temperature before the EGR valve in the prior art, because a condenser is arranged beside the EGR valve structure, a measuring point of a temperature sensor before the valve is easily influenced by heat radiation of the condenser, the temperature rise under the condition of non-high-flow fault can occur, and the temperature rise amplitude can be higher than the temperature rise under certain fault conditions, so that false alarm is easily caused. In other words, in the existing scheme for performing high-flow fault diagnosis on the EGR based on the temperature before the EGR valve, because of the influence of the structural design, the anti-interference capability of the scheme is poor, and the false alarm or the false alarm is easy to generate. At the same time, the application is forced to increase the formulation using additional auxiliary diagnosis, resulting in an increase in diagnosis cost.
Disclosure of Invention
In view of this, the present invention aims to provide a method, a system and a vehicle for EGR fault diagnosis, so as to solve the problems that the existing scheme for diagnosing high flow rate faults based on the pre-EGR valve temperature is affected by the structural design, has poor anti-interference capability, is easy to generate false reports or false reports, and is forced to add additional configuration for assisting diagnosis in application, thereby increasing the diagnosis cost.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a method of EGR fault diagnosis, the method comprising:
periodically detecting the pressure value of the gas at the rear end of the EGR valve;
determining the relation between the pressure value of the gas at the rear end of the EGR valve in the current period and a preset pressure value;
monitoring the temperature of the EGR valve end within the current period for a preset time according to the relation between the pressure value of the gas at the rear end of the EGR valve within the current period and a preset pressure value, and determining the relation between the temperature increment of the temperature of the EGR valve end within the preset time within the current period and the preset increment;
and when the pressure value of the gas at the rear end of the EGR valve in the current period is detected to be continuously larger than or equal to a preset pressure value and the temperature increment of the EGR valve end in the preset time exceeds a preset increment, outputting alarm information that the flow of the exhaust gas exceeds the standard.
Further, the method further comprises:
determining preset pressure values corresponding to working conditions of the vehicle in the current period, wherein different working conditions correspond to different preset pressure values;
when detecting that the pressure value of the gas at the rear end of the EGR valve in the current period is continuously greater than or equal to a preset pressure value, and the temperature of the EGR valve end exceeds a preset increment when the temperature increment in the preset time period exceeds the preset increment, outputting alarm information that the flow of the exhaust gas exceeds the standard, comprising the following steps:
and outputting alarm information that the exhaust gas flow exceeds the standard when the pressure value of the gas at the rear end of the EGR valve is greater than or equal to the preset pressure value in the current period and lasts for a first preset time and the temperature increment of the EGR valve end in the preset time exceeds the preset increment.
Further, the monitoring the temperature of the EGR valve end for a preset duration in the current period according to the relationship between the pressure value of the gas at the rear end of the EGR valve in the current period and a preset pressure value includes:
and when the pressure value of the gas at the rear end of the EGR valve in the current period is determined to be larger than or equal to the preset pressure value, monitoring the temperature of the EGR valve end in the current period for a preset time.
Further, the temperature increment is an increment between a first temperature and a second temperature, the first temperature is the temperature of the EGR valve end at the start time within a preset time period, and the second temperature is the temperature of the EGR valve end at the end time within a preset time period.
Further, the pressure value of the gas at the rear end of the EGR valve includes at least one of the pressure value of the exhaust gas after the EGR valve and the pressure value of the manifold gas at the intake manifold, wherein the manifold gas at the intake manifold is air or a mixed gas of air and the exhaust gas.
Further, when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current period is continuously greater than or equal to a preset pressure value and the temperature increment of the EGR valve end in the preset time exceeds a preset increment, outputting alarm information that the flow of the exhaust gas exceeds the standard, including:
when at least one of the pressure value of the exhaust gas close to the EGR valve in the current period is detected to be greater than or equal to a preset pressure value of the exhaust gas and last for a second preset time, and the pressure value of the manifold gas at the intake manifold in the current period is detected to be greater than or equal to a preset pressure value of the manifold gas and last for a third preset time is met, and when the temperature of the EGR valve end is in a temperature increment in the preset time length exceeds a preset increment, alarm information that the flow of the exhaust gas exceeds the standard is output.
Further, the periodically detecting the pressure value of the gas at the rear end of the EGR valve includes:
acquiring detection parameters of the periodic detection, including: detecting window time, detection interval time and continuous detection frequency;
and periodically detecting the pressure value of the gas at the rear end of the EGR valve based on the detection parameters.
Further, the method further comprises:
and outputting alarm information of the exhaust gas flow exceeding when the temperature of the EGR valve end exceeds the preset temperature. Compared with the prior art, the EGR fault diagnosis method has the following advantages:
(1) the EGR fault diagnosis method provided by the invention is based on a physical characteristic rule on the basis of not increasing additional sensor configuration, and saves hardware development and matching cost.
(2) The EGR fault diagnosis method provided by the invention is based on a combined judgment method of the pressure value of the gas at the rear end of the EGR valve and the temperature of the EGR valve end, so that the accuracy of EGR fault diagnosis is effectively increased, the possibility of false alarm and missed alarm is eliminated as far as possible, and the stricter regulation requirements are met.
The invention also aims to provide an EGR fault diagnosis system to solve the problems that the existing scheme for diagnosing high-flow faults based on the temperature before an EGR valve is influenced by structural design, has poor anti-interference capability and is easy to generate false reports or false reports, and meanwhile, additional preparation for assisting diagnosis is forced to be added in application, so that the diagnosis cost is increased.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a system for EGR fault diagnosis, the system comprising:
the detection module is used for periodically detecting the pressure value of the gas at the rear end of the EGR valve;
the first determining module is used for determining the relation between the pressure value of the gas at the rear end of the EGR valve in the current period and a preset pressure value;
the second determining module is used for monitoring the temperature of the EGR valve end in the current period for a preset time according to the relationship between the pressure value of the gas at the rear end of the EGR valve in the current period and a preset pressure value, and determining the relationship between the temperature increment of the temperature of the EGR valve end in the preset time and a preset increment in the current period;
and the warning module is used for outputting warning information that the exhaust gas flow exceeds the standard when the pressure value of the gas at the rear end of the EGR valve in the current period is detected to be continuously greater than or equal to a preset pressure value and the temperature of the EGR valve end exceeds a preset increment within the preset time.
Compared with the prior art, the EGR fault diagnosis system and the EGR fault diagnosis method have the same advantages, and are not described again.
Another objective of the present invention is to provide a vehicle, so as to solve the problems that the existing solution for diagnosing a high flow fault based on the temperature before the EGR valve is affected by the structural design, has poor anti-interference capability, and is prone to generating false alarm or missing report, and meanwhile, additional preparation for assisting diagnosis is forced to be added in the application, thereby increasing the diagnosis cost.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a vehicle, comprising: the EGR fault diagnosis system.
The vehicle and the EGR fault diagnosis system have the same advantages compared with the prior art, and the detailed description is omitted.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic diagram illustrating a method of EGR fault diagnosis in accordance with an embodiment of the present application;
FIG. 2 is a schematic diagram illustrating a method of EGR fault diagnosis according to an embodiment of the present application for periodically detecting a pressure value of an EGR valve back-end gas;
FIG. 3 is a cycle chart illustrating a method of EGR fault diagnosis in accordance with an embodiment of the present application;
FIG. 4 is a logic diagram illustrating pressure differential detection for a method of EGR fault diagnosis in accordance with an embodiment of the present application;
FIG. 5 is a logical relationship of temperature increase for a method of EGR fault diagnosis according to an embodiment of the present application;
FIG. 6 is a schematic diagram of a system for EGR fault diagnosis according to an embodiment of the present application.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Before describing the method for diagnosing the EGR fault provided in the present application, a brief description will be given below of a method for diagnosing a high flow rate fault based on the temperature before the EGR valve in the related art. The conventional method for diagnosing high-flow fault by temperature before the EGR valve is to arrange a temperature sensor in front of the EGR valve and determine whether the EGR flow is too high according to the measured temperature. In a tight coupling design structure of an EGR valve and a condenser, due to the limitation of narrow arrangement space, a measuring point of a temperature sensor in front of the valve is easily influenced by heat radiation of the condenser, temperature rise under the condition of non-high-flow fault can occur, the temperature rise amplitude can be higher than that under certain fault conditions, the method has poor anti-interference capability, missing report or misinformation can be easily generated, and meanwhile, EGR processing can not meet related specified requirements. At the same time, additional formulation specially used for auxiliary diagnosis is forced to be considered in the application process, and the cost is increased.
Therefore, the invention provides a method for diagnosing EGR fault based on the above problems, which effectively increases the accuracy of EGR fault diagnosis, eliminates the possibility of false alarm and missed alarm as much as possible and meets the requirements of stricter regulations through a combined judgment method based on the pressure value of the gas at the rear end of the EGR valve and the temperature at the end of the EGR valve. Meanwhile, the method provided by the invention does not need to add extra sensor preparation, and is based on the physical characteristic rule only, so that the hardware development and matching cost are effectively saved.
Fig. 1 is a schematic diagram of a method for diagnosing an EGR fault according to an embodiment of the present application. Referring to fig. 1, the method for diagnosing EGR fault provided by the present application includes the steps of:
step S11: the pressure value of the gas at the rear end of the EGR valve is periodically detected.
In the present embodiment, the vehicle state needs to be determined before the pressure value of the EGR valve rear end gas is periodically detected to implement the fault diagnosis of the EGR. Periodic detection of the pressure value of the EGR valve back end gas is initiated upon determination that the vehicle is in the preset state. The preset state of the vehicle is during non-dynamic transition working conditions such as parking idling or parking charging after the engine is started, no control system fault exists, and EGR is in a non-working state.
In this application, the periodic detection of the pressure value of the EGR valve back end gas includes: acquiring detection parameters of the periodic detection, including: detecting window time t w Detecting the interval time t wd Continuously detecting the frequency n; and periodically detecting the pressure value of the gas at the rear end of the EGR valve based on the detection parameters.
In this embodiment, the pressure value of the gas at the rear end of the EGR valve needs to be periodically detected according to the detection parameter that is periodically detected. Therefore, before periodically detecting the pressure value of the gas at the rear end of the EGR valve, the detection parameters of the periodic detection need to be obtained, including: detection window time, detection interval time, and continuous detection frequency.
Fig. 2 is a schematic diagram illustrating a method for diagnosing an EGR fault according to an embodiment of the present application, where pressure values of gas at a rear end of an EGR valve are periodically detected. Referring to fig. 2, each time the pressure value of the EGR valve back end gas is detected at the detection window time t w Internally, the time interval between two adjacent detections of the pressure value of the gas at the rear end of the EGR valve is detection interval time t wd The number of periodic detections for detecting the pressure value of the EGR valve rear end gas is the continuous detection frequency n.
Fig. 3 is a cycle diagram illustrating a method of EGR fault diagnosis according to an embodiment of the present application. Referring to fig. 3, before detecting the pressure value of the EGR valve back end gas in each detection window time in a complete periodic detection process, it is determined whether the vehicle is in a preset state. Stopping executing fault detection when the vehicle is determined not to be in the preset state; when the vehicle is determined to be in the preset state, activating the ith detection window, and if the ith detection window is in the time t w Reporting code without fault in the interior, detecting interval time t wd And then, when i of the ith detection window is determined to be smaller than n-1, performing 1 addition on i.
After the operation of adding 1 to i is carried out, when the vehicle is determined to be in a preset state, activating the detection window for the (i + 1) th time, and if the detection window time t is in the ith time w Reporting code without fault in the interior, detecting interval time t in the interval wd Then, when i +1 of the (i + 1) th detection window is determined to be smaller than n-1, the plus 1 operation is performed on the i + 1. Up to a certain detection window time t within a continuous detection frequency n w Reporting internal fault, outputting alarm information of waste gas flow exceeding standard, finishing diagnosis, or all detection window time t in continuous detection frequency n w And if no fault code is reported in the system, the diagnosis is ended. Wherein i is initially taken to be 1.
Step S12: and determining the relation between the pressure value of the gas at the back end of the EGR valve in the current period and a preset pressure value.
In the present embodiment, in the periodic detection of the pressure value of the EGR valve backend gas at step S11, step S12 determines the relationship between the pressure value of the EGR valve backend gas in the current period and the preset pressure value.
The relationship between the pressure value of the gas at the rear end of the EGR valve in the current period and the preset pressure value comprises the following steps: the pressure value of the gas at the rear end of the EGR valve in the current period is greater than or equal to a preset pressure value; and the pressure value of the gas at the rear end of the EGR valve in the current period is smaller than the preset pressure value. And the current period is the current times of detecting the pressure value of the gas at the rear end of the EGR valve.
Preferably, the preset pressure value is set according to actual requirements in the present invention, and is not particularly limited herein.
Illustratively, when the pressure value of the gas at the rear end of the EGR valve is detected within the 1 st detection window time, the current cycle is the 1 st detection window time, and the relationship between the pressure value of the gas at the rear end of the EGR valve and the preset pressure value in the detection process within the 1 st detection window time is determined. When the pressure value of the gas at the rear end of the EGR valve is detected within the nth detection window time, the current period is the nth detection window time, and the relation between the pressure value of the gas at the rear end of the EGR valve and the preset pressure value in the detection process within the nth detection window time is determined.
Step S13: monitoring the temperature of the EGR valve end within the current period for a preset time according to the relation between the pressure value of the gas at the rear end of the EGR valve within the current period and the preset pressure value, and determining the relation between the temperature increment of the temperature of the EGR valve end within the preset time within the current period and the preset increment.
In this embodiment, when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current period is greater than or equal to the preset pressure value, the monitoring of the temperature of the EGR valve end is started, and when the pressure value of the gas at the rear end of the EGR valve in the current period is detected, the monitoring of the preset duration is performed on the temperature of the EGR valve end in the current period. And in the process of monitoring the temperature of the EGR valve end for the preset time length in the current period, determining the relationship between the temperature increment and the preset increment of the temperature of the EGR valve end in the preset time length in the current period.
After EGR valve in present cycleWhen the pressure value of the end gas is less than the preset pressure value, detecting the interval time t at intervals wd Then, the pressure value of the gas at the rear end of the EGR valve is detected in the next cycle of the current cycle.
For example, when the current period is that the pressure value of the gas at the rear end of the EGR valve is detected within the 1 st detection window time, and when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current period is greater than or equal to the preset pressure value, the pressure value of the gas at the rear end of the EGR valve is detected within the current period, and meanwhile, the temperature of the EGR valve end is monitored within the current period for the preset time.
When the pressure value of the gas at the rear end of the EGR valve is detected within the 1 st detection window time in the current period, and the pressure value of the gas at the rear end of the EGR valve is detected to be smaller than the preset pressure value in the current period, the interval detection interval time t is detected wd And then, when the vehicle is determined to be in the preset state, detecting the pressure value of the gas at the rear end of the EGR valve within the time of the 2 nd detection window. And detecting the pressure value of the gas at the rear end of the EGR valve within the nth detection window time when all detection results before the nth detection window time are that the pressure value of the gas at the rear end of the EGR valve is smaller than the preset pressure value. And when the detection result in the nth detection window time is that the pressure value of the gas at the rear end of the EGR valve is smaller than the preset pressure value, ending the periodic detection of the pressure value of the gas at the rear end of the EGR valve by the wheel.
The relationship between the temperature increment of the EGR valve end in the preset time period in the current period and the preset increment comprises the following steps: the increment of the temperature of the EGR valve end within the preset time length exceeds the preset increment; the increase in the temperature of the EGR valve end for the preset period of time does not exceed the preset increase.
Step S14: and when the pressure value of the gas at the rear end of the EGR valve in the current period is detected to be continuously larger than or equal to a preset pressure value and the temperature increment of the EGR valve end in the preset time exceeds a preset increment, outputting alarm information that the flow of the exhaust gas exceeds the standard.
In this embodiment, when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current period is greater than or equal to the preset pressure value and the duration exceeds the preset duration, and when the increment of the temperature at the EGR valve end in the preset duration in the current period exceeds the preset increment, the alarm information that the exhaust gas flow of the EGE valve exceeds the standard is output, and the periodic detection of the wheel is ended.
In this embodiment, when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current period is smaller than the preset pressure value, or the pressure value of the gas at the rear end of the EGR valve in the current period is greater than or equal to the preset pressure value, but the duration does not exceed the preset duration, and the vehicle is in the preset state, the detection of the pressure value of the gas at the rear end of the EGR valve in the next period of the current period is performed.
In this embodiment, when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current period is greater than or equal to the preset pressure value and continuously exceeds the set time period, but the increment of the temperature at the end of the EGR valve in the preset time period in the current period does not exceed the preset increment, and the vehicle is in the preset state, the detection of the pressure value of the gas at the rear end of the EGR valve in the next period of the current period is performed.
Compared with the existing scheme of carrying out high-flow fault diagnosis on the EGR based on the temperature before the EGR valve, the method has higher accuracy and meets the more severe regulation requirements.
According to the method, when the pressure value of the gas at the rear end of the EGR valve and the temperature of the EGR valve end are measured, detection is continuously carried out for a period of time, and the exhaust gas flow of the EGE valve is determined to be over-standard only when the judgment condition is continuously met in the continuous detection process, so that the possibility of false alarm and missed alarm is effectively reduced.
The method provided by the invention does not need to add extra sensor preparation, is only based on the physical characteristic rule, and effectively saves hardware development and matching cost.
In this application, the method further comprises: determining preset pressure values corresponding to working conditions of the vehicle in the current period, wherein different working conditions correspond to different preset pressure values; when detecting that the pressure value of the gas at the rear end of the EGR valve in the current period is continuously greater than or equal to a preset pressure value, and the temperature of the EGR valve end exceeds a preset increment when the temperature increment in the preset time period exceeds the preset increment, outputting alarm information that the flow of the exhaust gas exceeds the standard, comprising the following steps: and outputting alarm information that the exhaust gas flow exceeds the standard when the pressure value of the gas at the rear end of the EGR valve is greater than or equal to the preset pressure value in the current period and lasts for a first preset time and the temperature increment of the EGR valve end in the preset time exceeds the preset increment.
In this embodiment, the vehicle needs to run under different environments, which will affect the detection of the gas pressure at the rear end of the EGR valve. In a high altitude environment, the ambient air pressure is lower than a standard atmospheric pressure; in low altitude environments, the ambient air pressure is above one standard atmosphere. Since the ambient pressure is different in different environments, the pressure of the gas at the rear end of the EGR valve detected in different environments will be different. The pressure of the EGR valve back end gas detected in the high altitude environment is lower than the pressure of the EGR valve back end gas detected in the normal environment, and the pressure of the EGR valve back end gas detected in the low altitude environment is higher than the pressure of the EGR valve back end gas detected in the normal environment. Therefore, a fixed preset pressure value is set in different environments to judge whether the flow of the exhaust gas at the rear end of the EGR valve exceeds the standard or not, the accuracy is reduced, different values are taken for the preset pressure value according to different environments, the influence of environmental errors on the detection of the pressure value of the gas at the rear end of the EGR valve is avoided, and the accuracy of a judgment condition that whether the flow of the exhaust gas at the rear end of the EGR valve exceeds the standard or not is effectively improved by taking the preset pressure value in different environments as the judgment condition. Based on the method, different preset pressure values are set according to different working conditions of the vehicle in the current period. When the ambient pressure is high, the preset pressure value is increased, and when the ambient pressure is low, the preset pressure value is decreased. Wherein the operating conditions include at least ambient pressure.
In this embodiment, another optional implementation manner of detecting that the pressure value of the gas at the rear end of the EGR valve in the current period is greater than or equal to the preset pressure value and lasts for the first preset time is to detect that a difference value between the pressure value of the gas at the rear end of the EGR valve in the current period and the expected pressure value is greater than or equal to a differential pressure threshold value and lasts for the first preset time. The expected pressure value is different values according to different environments, and the sum of the expected pressure value and the pressure difference threshold is a preset pressure value.
In this embodiment, the specific value of the preset pressure value determined based on the working condition of the vehicle in the current period is set according to an actual application scenario, which is not specifically limited herein.
In this embodiment, after determining the preset pressure value corresponding to the working condition of the vehicle in the current period, the relationship between the pressure value of the gas at the rear end of the EGR valve in the current period and the preset pressure value is detected. When the pressure value of the gas at the rear end of the EGR valve in the current period is detected to be larger than or equal to the preset pressure value, the monitoring of the temperature of the EGR valve end is started, and when the pressure value of the gas at the rear end of the EGR valve in the current period is detected, the monitoring of the preset duration of the temperature of the EGR valve end in the current period is carried out.
And outputting alarm information of the exhaust gas flow exceeding when the pressure value of the gas at the rear end of the EGR valve in the current period is detected to be larger than or equal to a preset pressure value corresponding to the working condition in the current period and lasts for a first preset time, and the temperature increment of the temperature at the end of the EGR valve in the preset time length is detected to exceed the preset increment.
Preferably, in the present invention, the first preset time is set according to an actual requirement, and is not limited in particular.
In this embodiment, the first preset time is a duration that the pressure value of the gas at the rear end of the EGR valve continuously exceeds a preset pressure value, and the preset duration is a duration for monitoring the temperature of the EGR valve end. When the pressure value of the gas at the rear end of the EGR valve exceeds the preset pressure value, the monitoring of the temperature of the EGR valve end is started immediately. Therefore, the starting time of the first preset time and the starting time of the preset time duration in the same detection window time are the same, and the time duration of the first preset time and the time duration of the preset time duration is less than or equal to one detection window time. The ending time of the first preset time and the ending time of the preset duration are set according to an actual application scenario, and may be the same or different, and are not specifically limited herein.
In this application, according to in the current cycle the relation between the pressure value of EGR valve rear end gas and the predetermined pressure value, it is right in the current cycle the temperature of EGR valve end carries out the monitoring of predetermineeing for a long time, include: and when the pressure value of the gas at the rear end of the EGR valve in the current period is determined to be larger than or equal to the preset pressure value, monitoring the temperature of the EGR valve end in the current period for a preset time.
In this embodiment, when it is determined that the pressure value of the gas at the rear end of the EGR valve in the current period is greater than or equal to the preset pressure value, the pressure value of the gas at the rear end of the EGR valve in the current period is detected, and meanwhile, the temperature of the EGR valve end in the current period is monitored for the preset time.
And when the pressure value of the gas at the rear end of the EGR valve in the current period is determined to be smaller than the preset pressure value and the vehicle is in the preset state, detecting the pressure value of the gas at the rear end of the EGR valve in the next period of the current period.
In this application, the temperature increment is an increment between a first temperature and a second temperature, the first temperature is the temperature of the EGR valve end at the start time within a preset time period, and the second temperature is the temperature of the EGR valve end at the end time within the preset time period.
In this embodiment, the determining the relationship between the temperature increment and the preset increment of the temperature of the EGR valve end in the preset time period in the current cycle specifically includes: in the process of monitoring the temperature of the EGR valve end for the preset time period in the current period, the first temperature of the EGR valve end measured at the starting moment in the preset time period is determined, and the second temperature of the EGR valve end measured at the ending moment in the preset time period is determined. And differentiating the second temperature with the first temperature to obtain the temperature increment of the EGR valve end within a preset time length, and determining whether the temperature increment exceeds a preset increment.
Preferably, in the present invention, the second temperature must be greater than the first temperature, and the first temperature is set to a temperature that is less than the second temperature according to actual demand, the second temperature and the preset increment are set according to actual demand, and are not particularly limited herein.
In the present application, the pressure value of the gas at the rear end of the EGR valve includes at least one of the pressure value of the exhaust gas after approaching the EGR valve and the pressure value of the manifold gas at the intake manifold, wherein the manifold gas at the intake manifold is air or a mixture of air and the exhaust gas.
In the embodiment, during the process that the exhaust gas generated by the diesel engine or the gasoline engine enters the cylinder for combustion through the EGR valve, the exhaust gas needs to pass through the intake manifold, and the exhaust gas and the combustible mixture enter the cylinder for combustion in the intake manifold. After passing through the EGR valve, the exhaust gas needs to pass through a section of pipeline and then enter the intake manifold. In order to further avoid the influence of a condenser arranged near an EGR valve on the whole detection process, the false alarm of fault detection is caused. The periodic detection of the pressure value of the gas at the rear end of the EGR valve is performed by periodically detecting the pressure value of the exhaust gas after approaching the EGR valve and periodically detecting the pressure value of the manifold gas at the intake manifold at the same time. And if one pressure value meets the set judgment condition, the pressure value is determined to meet the set judgment condition.
The set determination conditions are each determination condition corresponding to the pressure value of the EGR valve rear end gas, and are not described herein again. If the pressure value of the gas at the rear end of the EGR valve is greater than or equal to the preset pressure value and lasts for the first preset time, the corresponding determination conditions are whether the pressure value of the exhaust gas near the EGR valve is greater than or equal to the preset pressure value and lasts for the first preset time, and/or whether the pressure value of the manifold gas at the intake manifold is greater than or equal to the preset pressure value and lasts for the first preset time.
In this application, when detecting in the current cycle the gaseous pressure value in EGR valve rear end lasts more than or equal to preset pressure value, just the temperature of EGR valve end is in when the temperature increment in the length of time of presetting surpasss the preset increment, the alarm information that the output exhaust gas flow exceeds standard includes: when at least one of the pressure value of the exhaust gas close to the EGR valve in the current period is detected to be greater than or equal to a preset pressure value of the exhaust gas and last for a second preset time, and the pressure value of the manifold gas at the intake manifold in the current period is detected to be greater than or equal to a preset pressure value of the manifold gas and last for a third preset time is met, and when the temperature of the EGR valve end is in a temperature increment in the preset time length exceeds a preset increment, alarm information that the flow of the exhaust gas exceeds the standard is output.
In this embodiment, the preset pressure value of the exhaust gas and the preset pressure value of the manifold gas can be determined according to the working condition of the vehicle in the current period. And after the preset pressure value of the exhaust gas and the preset pressure value of the manifold gas corresponding to the working condition of the vehicle in the current period are determined, fault diagnosis is carried out.
In the embodiment, at least one of the time when the pressure value of the exhaust gas after approaching the EGR valve in the current period is detected to be greater than or equal to the preset pressure value of the exhaust gas for the second preset time and the time when the pressure value of the manifold gas at the intake manifold in the current period is detected to be greater than or equal to the preset pressure value of the manifold gas for the third preset time is detected to be greater than or equal to the preset pressure value of the manifold gas; meanwhile, in the process of monitoring the temperature of the EGR valve end for the preset time period in the current period, when the temperature increment between the first temperature of the EGR valve end measured at the starting time in the preset time period and the second temperature of the EGR valve end measured at the ending time in the preset time period exceeds the preset increment, the alarm information that the exhaust gas flow exceeds the standard is output, and the periodic detection of the cycle is finished.
Preferably, in the present invention, the preset pressure value of the exhaust gas and the preset pressure value of the manifold gas may be set according to actual requirements, and the preset pressure values may be the same as each other, and may be different from each other, which is not specifically limited herein; the first preset time, the second preset time and the third preset time can be set according to actual requirements, and the first preset time, the second preset time and the third preset time can be the same or different and are not specifically limited herein.
Fig. 4 is a logic diagram of pressure difference detection of a method of EGR fault diagnosis according to an embodiment of the present application. Referring to fig. 4, before each test in a complete periodic test, it is determined whether the vehicle is in a predetermined condition. When the vehicle is determined to be in the preset state, the detection of the current period is executed, and the detection of the current period is executedIn the process, the pressure value DP of the exhaust gas after the approach to the EGR valve is determined EGRA With a predetermined pressure value DP of the exhaust gas uplimEGR And determining a pressure value DP of the manifold gas at the intake manifold S Predetermined pressure value DP of manifold gas uplimS In determining DP EGRA ≥DP uplimEGR And DP S ≥DP uplimS And when at least one of the pressure sensors is satisfied, activating a timer for judging the overrun of the differential pressure.
At D PEGRA ≥DP uplimEGR When the EGR valve is in the middle of the EGR valve, a counter t for over-limit judgment of the differential pressure after the EGR valve is closed is activated DPR0 (ii) a At DP S ≥DP uplimS When the pressure difference at the intake manifold is over-limit, a counter t for over-limit judgment is activated DPS0 (ii) a In determining D PEGRA ≥DP uplimEGR And DP S ≥DP uplimS When the two are simultaneously established, the timer t is activated simultaneously DPR0 And a timer t DPS0 。
The respective pressure difference durations are determined by respective activated counters after proximity to the EGR valve and at the intake manifold. At the determination of D PEGRA ≥DP uplimEGR When, activating the counter t DPR0 Through a counter t DPR0 Determination of D PEGRA ≥DP uplimEGR Duration t of DPR0 And a second predetermined time t DPRlim0 The relationship (2) of (c). In determining DP S ≥DP uplimS When, the counter t is activated DPS0 Through a counter t DPS0 Determining DP S ≥DP uplimS Duration t of DPS0 And a second preset time t DPSlim0 The relationship (c) in (c).
At t DPR0 ≥t DPRlim0 And t DPS0 ≥t DPSlim0 When at least one of the two is established, it is determined that the differential pressure of the gas at the rear end of the EGR valve exceeds the limit. At t DPR0 ≥t DPRlim0 And t DPS0 ≥t DPSlim0 And if the pressure value of the gas at the rear end of the EGR valve is not satisfied, performing time debounce, and entering a next period of the current period to detect the pressure value of the gas at the rear end of the EGR valve when the vehicle is determined to be in a preset state.
In the present application, the method further comprises: and outputting alarm information of the exhaust gas flow exceeding when the temperature of the EGR valve end exceeds the preset temperature.
In this embodiment, a protection limit temperature with an upper limit, i.e., a preset temperature, is set for the temperature of the EGR valve end, and when the temperature of the EGR valve end exceeds the preset temperature, an alarm message indicating that the exhaust gas flow exceeds the standard is directly output.
FIG. 5 is a logical relationship diagram illustrating temperature increase for a method of EGR fault diagnosis according to an embodiment of the present application. Referring to fig. 5, when it is determined that the vehicle is in the preset state, the current cycle is started to detect the pressure value of the gas at the rear end of the EGR valve, when it is determined that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value, a timer for performing overrun judgment on the pressure difference is activated, the pressure value of the gas at the rear end of the EGR valve in the current cycle is detected, and meanwhile, the temperature of the EGR valve end is monitored for a preset duration in the current cycle.
And recording the measured temperature of the EGR valve end in the monitoring process of presetting time length for the temperature of the EGR valve end in the current period, and timing and storing the measured temperature of the EGR valve end. Detecting a starting time t within a preset time length 0 Measured first temperature T of EGR valve end egr0 And a termination time t within a predetermined time period 1 Measured second temperature T of EGR valve end egr1 Temperature increase DT between egr More than or equal to a preset increment DT egrlim It is determined that the temperature increase in the EGR valve end temperature is out of limit. Or directly detecting the temperature T of the EGR valve end egr Not less than the preset temperature T Protectlim And directly outputting the alarm information of the exhaust gas flow exceeding the standard.
At DT egr ＜DT egrlim And when the temperature increment of the temperature of the EGR valve end is determined not to exceed the limit, time bounce is carried out, and when the vehicle is determined to be in the preset state, the pressure value of the gas at the rear end of the EGR valve is detected in the next period of the current period. When the pressure value of the gas at the rear end of the EGR valve in the next period of the current period is determined to be larger than or equal to the preset pressure value, activating a timer for carrying out overrun judgment on the pressure difference, and detecting the pressure value of the gas at the rear end of the EGR valve in the next period of the current periodAnd meanwhile, monitoring the temperature of the EGR valve end for a preset time in the next period of the current period.
In summary, the method for diagnosing the EGR fault according to the embodiment of the present invention at least includes the following advantages:
the EGR fault diagnosis method provided by the invention is based on a combined judgment method of two pressure values of gas at the rear end of the EGR valve and the temperature of the EGR valve end, so that the accuracy of fault diagnosis of the EGR valve is effectively improved, the possibility of misinformation and missing report is eliminated as much as possible, and the stricter regulation requirements are met.
Meanwhile, the EGR fault diagnosis method does not need to add extra sensor preparation, and only diagnoses the EGR fault based on the physical characteristic rule, thereby saving the hardware development and the matching cost.
The embodiment of the invention also provides an EGR fault diagnosis system. FIG. 6 is a schematic diagram of a system for EGR fault diagnosis according to an embodiment of the present application. Referring to fig. 6, the present application provides a system 600 for EGR fault diagnosis comprising:
the detection module 601 is configured to periodically detect a pressure value of gas at a rear end of the EGR valve.
The first determination module 602 is configured to determine a relationship between a pressure value of the gas at the rear end of the EGR valve in a current period and a preset pressure value.
The second determining module 603 is configured to monitor the temperature of the EGR valve end in the current period for a preset duration according to a relationship between a pressure value of the gas at the rear end of the EGR valve in the current period and a preset pressure value, and determine a relationship between a temperature increment of the temperature of the EGR valve end in the preset duration and a preset increment in the current period.
And the warning module 604 is configured to output warning information that the exhaust gas flow exceeds the standard when the pressure value of the gas at the rear end of the EGR valve is detected to be continuously greater than or equal to a preset pressure value in the current period and the temperature increment of the temperature at the end of the EGR valve in the preset time exceeds a preset increment.
The embodiment of the invention also provides a vehicle, which specifically comprises: the EGR fault diagnosis system.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (10)

1. A method of EGR fault diagnosis, the method comprising:
periodically detecting the pressure value of the gas at the rear end of the EGR valve;
determining the relation between the pressure value of the gas at the rear end of the EGR valve in the current period and a preset pressure value;
monitoring the temperature of the EGR valve end within the current period for a preset time according to the relation between the pressure value of the gas at the rear end of the EGR valve within the current period and a preset pressure value, and determining the relation between the temperature increment of the temperature of the EGR valve end within the preset time within the current period and the preset increment;
and when the pressure value of the gas at the rear end of the EGR valve in the current period is detected to be continuously larger than or equal to a preset pressure value and the temperature increment of the EGR valve end in the preset time exceeds a preset increment, outputting alarm information that the flow of the exhaust gas exceeds the standard.
2. The method of claim 1, further comprising:
determining preset pressure values corresponding to working conditions of the vehicle in the current period, wherein different working conditions correspond to different preset pressure values;
when the pressure value of the gas at the rear end of the EGR valve in the current period is detected to be continuously greater than or equal to a preset pressure value, and the temperature increment of the temperature of the EGR valve end in the preset time exceeds a preset increment, outputting alarm information that the flow of the exhaust gas exceeds the standard, wherein the alarm information comprises:
and outputting alarm information that the flow of the exhaust gas exceeds the standard when the pressure value of the gas at the rear end of the EGR valve is larger than or equal to the preset pressure value in the current period and lasts for a first preset time and the temperature increment of the temperature at the end of the EGR valve in the preset time exceeds the preset increment.
3. The method of claim 1, wherein the monitoring the temperature of the EGR valve end for a preset duration in a current cycle based on a relationship between a pressure value of the EGR valve back-end gas in the current cycle and a preset pressure value comprises:
and when the pressure value of the gas at the rear end of the EGR valve in the current period is determined to be larger than or equal to the preset pressure value, monitoring the temperature of the EGR valve end in the current period for a preset time.
4. The method of claim 1, wherein the temperature increase is an increase between a first temperature and a second temperature, the first temperature being a temperature of the EGR valve end at a start time within a preset time period, the second temperature being a temperature of the EGR valve end at an end time within a preset time period.
5. The method of claim 1, wherein the pressure value of the EGR valve back end gas comprises at least one of a pressure value of exhaust gas near the EGR valve and a pressure value of manifold gas at an intake manifold, wherein the manifold gas at the intake manifold is air or a mixture of air and the exhaust gas.
6. The method of claim 5, wherein the outputting of the warning message that the exhaust gas flow exceeds the standard when the pressure value of the gas at the back end of the EGR valve is continuously detected to be greater than or equal to the preset pressure value in the current period and the temperature of the EGR valve end is increased by the preset increment within the preset time period comprises:
when at least one of the pressure value of the exhaust gas close to the EGR valve in the current period is detected to be greater than or equal to a preset pressure value of the exhaust gas and last for a second preset time, and the pressure value of the manifold gas at the intake manifold in the current period is detected to be greater than or equal to a preset pressure value of the manifold gas and last for a third preset time is met, and when the temperature of the EGR valve end is in a temperature increment in the preset time length exceeds a preset increment, alarm information that the flow of the exhaust gas exceeds the standard is output.
7. The method of claim 1, wherein the periodically detecting the pressure value of the EGR valve back-end gas comprises:
acquiring detection parameters of the periodic detection, including: detecting window time, detection interval time and continuous detection frequency;
and periodically detecting the pressure value of the gas at the rear end of the EGR valve based on the detection parameters.
8. The method of claim 1, further comprising:
and outputting alarm information of the exhaust gas flow exceeding when the temperature of the EGR valve end exceeds the preset temperature.
9. A system for EGR fault diagnosis, the system comprising:
the detection module is used for periodically detecting the pressure value of the gas at the rear end of the EGR valve;
the first determining module is used for determining the relation between the pressure value of the gas at the rear end of the EGR valve in the current period and a preset pressure value;
the second determining module is used for monitoring the temperature of the EGR valve end in the current period for a preset time according to the relationship between the pressure value of the gas at the rear end of the EGR valve in the current period and a preset pressure value, and determining the relationship between the temperature increment of the temperature of the EGR valve end in the preset time and a preset increment in the current period;
and the warning module is used for outputting warning information that the exhaust gas flow exceeds the standard when the pressure value of the gas at the rear end of the EGR valve in the current period is detected to be continuously greater than or equal to a preset pressure value and the temperature of the EGR valve end exceeds a preset increment within the preset time.
10. A vehicle comprising an EGR fault diagnosis system according to claim 9 for performing the steps of the EGR fault diagnosis method according to any one of claims 1 to 8.
CN202110720286.0A 2021-06-28 2021-06-28 EGR fault diagnosis method and system and vehicle Pending CN114791726A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110720286.0A CN114791726A (en) 2021-06-28 2021-06-28 EGR fault diagnosis method and system and vehicle

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110720286.0A CN114791726A (en) 2021-06-28 2021-06-28 EGR fault diagnosis method and system and vehicle

Publications (1)

Publication Number Publication Date
CN114791726A true CN114791726A (en) 2022-07-26

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Application Number Title Priority Date Filing Date
CN202110720286.0A Pending CN114791726A (en) 2021-06-28 2021-06-28 EGR fault diagnosis method and system and vehicle

Country Status (1)

Country Link
CN (1) CN114791726A (en)

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