CN113756999A - EGR flow fault detection method and device - Google Patents

EGR flow fault detection method and device Download PDF

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Publication number
CN113756999A
CN113756999A CN202110927825.8A CN202110927825A CN113756999A CN 113756999 A CN113756999 A CN 113756999A CN 202110927825 A CN202110927825 A CN 202110927825A CN 113756999 A CN113756999 A CN 113756999A
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egr
fault
egr system
temperature
value
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CN113756999B (en
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申付松
田良云
刘勤
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United Automotive Electronic Systems Co Ltd
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United Automotive Electronic Systems Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/49—Detecting, diagnosing or indicating an abnormal function of the EGR system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust-Gas Circulating Devices (AREA)

Abstract

The application discloses an EGR flow fault detection method and device, and relates to the technical field of automobiles. The EGR flow fault detection method comprises the steps of detecting whether a high flow fault occurs in an EGR system according to the temperature rise of the temperature of an EGR inlet after an engine is started and before the EGR system works; when the EGR system works, detecting whether the low flow fault occurs in the EGR system according to a signal value of a knock sensor and the temperature rise of the EGR inlet temperature; the problem of low accuracy of the existing EGR flow fault detection is solved; the method and the device have the advantages that the detection cost of the flow faults of the EGR system is reduced, and the detection accuracy of the flow faults of the EGR system is improved.

Description

EGR flow fault detection method and device
Technical Field
The application relates to the technical field of automobiles, in particular to an EGR flow fault detection method, device and storage medium.
Background
As the demand for emissions and fuel consumption of vehicles further increases, more and more vehicles are equipped with EGR (Exhaust Gas Recirculation) systems. The EGR system returns a portion of the exhaust gas from the engine to the intake manifold and mixes with fresh air to re-enter the cylinders of the engine. Because the waste gas contains a large amount of CO2And the like, which can lower the maximum combustion temperature of the air-fuel mixture in the cylinder, thereby reducing the amount of nitrogen oxides produced.
The EGR system can be structurally divided into an internal EGR system and an external EGR system, and the external EGR system can realize accurate control of the flow rate of exhaust gas, and is widely applied. The external EGR system is divided into a high-pressure EGR system and a low-pressure EGR system according to the difference in the gas intake point of the exhaust gas. As shown in fig. 1, a high pressure EGR system typically includes critical components such as an EGR valve 11, an EGR cooler 12, an EGR inlet temperature sensor 13, and the like.
In order to ensure that the EGR system can work normally and ensure that the vehicle does not have the problem of emission deterioration or fuel consumption increase caused by faults such as too low or too high EGR flow, the emission regulations require that faults such as too high or too low EGR flow are diagnosed clearly. The currently commonly used methods for diagnosing the EGR flow fault include the following methods: 1. judging the concentration state deviation of the mixed gas during the EGR operation/non-operation; 2. and judging by calculating the deviation between the flow rate and the actual flow rate of HFM (air mass flow meter). However, the above diagnosis method has the defects of false alarm, missing alarm, high cost and the like.
Disclosure of Invention
In order to solve the problems in the related art, the application provides an EGR flow fault detection method, an EGR flow fault detection device and a storage medium. The technical scheme is as follows:
in a first aspect, an embodiment of the present application provides an EGR flow fault detection method, where the method includes:
after the engine is started and before the EGR system works, detecting whether the EGR system has a high-flow fault according to the temperature rise of the EGR inlet temperature;
and when the EGR system works, detecting whether the low flow fault occurs in the EGR system according to the signal value of the knock sensor and the temperature rise of the EGR inlet temperature.
Optionally, detecting whether the EGR system has a high flow fault according to the temperature rise of the EGR inlet temperature includes:
acquiring EGR inlet temperature and recording as a first temperature value;
in a high-flow fault diagnosis period, acquiring a first maximum temperature rise of EGR inlet temperature;
detecting whether the first maximum temperature rise is greater than a first temperature threshold;
if the first maximum temperature rise is detected to be larger than a first temperature threshold value, determining that the EGR system has a high-flow fault;
and if the first maximum temperature rise is not larger than the first temperature threshold value, determining that the high flow fault does not occur in the EGR system.
Optionally, obtaining the EGR inlet temperature and recording as the first temperature value comprises:
when a first predetermined condition is met, the EGR inlet temperature is obtained and recorded as a first temperature value.
Optionally, the first predetermined condition is that the temperature value of the turbocharger inlet gas model is greater than a first calibrated temperature threshold.
Optionally, when the EGR system is in operation, detecting whether the EGR system has a low flow fault according to a signal value of the knock sensor and a temperature rise of the EGR inlet temperature, including:
when the EGR system works, whether the low flow fault occurs in the EGR system is detected according to a signal value of a knock sensor, and a first fault mark value is obtained;
when the EGR system works, whether the low flow fault occurs in the EGR system is detected according to the temperature rise of the temperature of the EGR inlet, and a second fault mark value is obtained;
when the first fault flag value and the second fault flag value both indicate that the low-flow fault does not occur in the EGR system, determining that the low-flow fault does not occur in the EGR fault system;
and when the first fault mark value or the second fault mark value indicates that the low-flow fault occurs in the EGR system, determining that the low-flow fault occurs in the EGR fault system, and stopping detecting the low-flow fault.
Optionally, detecting whether the EGR system has a low flow fault according to a signal value of the knock sensor to obtain a first fault flag value, including:
and when a second preset condition is met, detecting whether the EGR system has a low flow fault or not according to the signal value of the knock sensor to obtain a first fault mark value.
Optionally, detecting whether the EGR system has a low flow fault according to a signal value of the knock sensor to obtain a first fault flag value, including:
acquiring the accumulated time of a signal value of the detonation sensor being 1 in a first low-flow fault diagnosis period;
detecting whether the accumulated time is greater than a time threshold;
if the accumulated time is detected to be larger than the time threshold, outputting a first fault mark value indicating that the low flow fault occurs in the EGR system;
if the accumulated time is not greater than the time threshold, a first fault flag value is output indicating that the low flow fault does not occur in the EGR system.
Optionally, the second predetermined condition is the EGR target flow being greater than the first flow threshold.
Optionally, the method further includes:
and stopping low flow fault detection of the EGR system according to the signal value of the knock sensor when a second preset condition is not met in the first low flow fault diagnosis period.
Alternatively, when the first fault flag value indicates a low flow fault in the EGR system, the engine is controlled to enter a limp home mode and the EGR system is shut down.
Optionally, detecting whether the EGR system has a low flow fault according to the temperature rise of the EGR inlet to obtain a second fault flag value, including:
and when a third preset condition is met, detecting whether the low flow fault occurs in the EGR system according to the temperature rise of the EGR inlet to obtain a second fault mark value.
Optionally, detecting whether the EGR system has a low flow fault according to the temperature rise of the EGR inlet temperature to obtain a second fault flag value, including:
acquiring EGR inlet temperature and recording as a second temperature value;
acquiring a second maximum temperature rise of the EGR inlet temperature in a second low-flow fault diagnosis period;
detecting whether the second maximum temperature rise is greater than a second temperature threshold;
if the second maximum temperature rise is detected to be larger than the second temperature threshold, outputting a second fault flag value indicating that the low-flow fault does not occur in the EGR system;
and if the second maximum temperature rise is not greater than the second temperature threshold value, outputting a second fault flag value indicating that the low flow fault occurs in the EGR system.
Optionally, the third predetermined condition is the EGR target flow being greater than the second flow threshold.
Optionally, the method further includes:
and stopping low flow fault detection of the EGR system according to the temperature rise amount of the EGR inlet when a third preset condition is not met in the second low flow fault diagnosis period.
Optionally, the EGR system is an external EGR system.
In a second aspect, an embodiment of the present application provides an EGR flow fault detection apparatus, which includes a processor and a memory; the memory has stored therein a program that is loaded and executed by the processor to implement the method as described in the first aspect above.
In a third aspect, an embodiment of the present application provides a computer-readable storage medium, in which a program is stored, and the program is loaded and executed by a processor to implement the method as shown in the first aspect.
The technical scheme at least comprises the following advantages:
after the engine is started and before the EGR system works, whether the high flow fault occurs in the EGR system is detected according to the temperature rise of the EGR inlet temperature, and whether the low flow fault occurs in the EGR system is detected according to the signal value of the knock sensor and the temperature rise of the EGR inlet temperature when the EGR system works; the method has the advantages that the flow fault of the EGR system is detected through the knock sensor and the EGR temperature sensor which are configured on the vehicle, so that the problem of low accuracy of the existing EGR flow fault detection is solved; the method and the device have the advantages that the detection cost of the flow faults of the EGR system is reduced, and the detection accuracy of the flow faults of the EGR system is improved.
Drawings
In order to more clearly illustrate the detailed description of the present application or the technical solutions in the prior art, the drawings needed to be used in the detailed description of the present application or the prior art description will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic diagram of a high pressure EGR arrangement for augmenting an engine;
FIG. 2 is a flow chart of a method for EGR flow fault detection provided by an embodiment of the present application;
FIG. 3 is a logic diagram of a method for EGR system flow fault detection provided by an embodiment of the present application;
FIG. 4 is a block diagram of an EGR flow fault detection apparatus provided in an exemplary embodiment of the present application;
wherein: 11, an EGR valve; 12, an EGR cooler; 13, an EGR inlet temperature sensor; 14, a throttle valve; 15, an intake pressure temperature sensor; 16, an engine; 17, air filtering; 18, a supercharger; 19, a catalyst; 20, a silencer.
Detailed Description
The technical solutions in the present application will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," and "third" are used for descriptive and differential purposes only and are not to be construed as indicating or implying relative importance, nor order.
In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; the connection can be mechanical connection or electrical connection; the two elements may be directly connected or indirectly connected through an intermediate medium, or may be communicated with each other inside the two elements, or may be wirelessly connected or wired connected. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.
In addition, the technical features mentioned in the different embodiments of the present application described below may be combined with each other as long as they do not conflict with each other.
In a vehicle equipped with an EGR system, when the engine water temperature is low and the operation is unstable in order to maintain stable combustion of the engine mixture, the vehicle control system closes the EGR valve, and at this time, the temperature rise detected by the EGR inlet temperature sensor is mainly caused by heating of the exhaust gas in the engine body and the intake pipe of the EGR system, but since the exhaust gas flow speed near the EGR temperature inlet sensor is slow at this time, the temperature near the EGR temperature inlet sensor (i.e., the EGR inlet temperature) rises slowly. When the EGR system works normally, the EGR valve is opened, high-temperature waste gas can quickly wash the EGR inlet temperature sensor, and the temperature detected by the EGR inlet temperature sensor is quickly increased.
When the EGR system develops a low flow fault, even if the vehicle control system controls the EGR system to turn on, no significant amount of exhaust gas flows quickly through the EGR inlet temperature sensor, resulting in a slow or no increase in the temperature detected by the EGR inlet temperature sensor.
When the EGR system develops a high flow fault, even if the vehicle control system controls the EGR system to shut down, there is a large amount of exhaust that quickly flows through the EGR inlet temperature sensor, causing the temperature detected by the EGR inlet temperature sensor to rise quickly.
In order to improve the accuracy of the EGR flow fault detection and reduce the detection cost of the EGR flow fault, an embodiment of the present application provides an EGR flow fault detection method, please refer to fig. 2, which shows a flowchart of the EGR flow fault detection method, and the method at least includes the following steps:
in step 201, after the engine is started and before the EGR system is operated, whether the EGR system has a high flow fault is detected according to the temperature rise amount of the EGR inlet temperature.
The opening and closing of the EGR system is controlled by the vehicle control system. Optionally, the state of an EGR valve in the EGR system is controlled by the vehicle control system, when the EGR valve is controlled to be opened, the EGR system works, and when the EGR valve is controlled to be closed, the EGR system does not work.
The EGR inlet temperature is detected through the EGR inlet temperature sensor, the detected EGR inlet temperature is sent to the vehicle control system, and the vehicle control system calculates the temperature rise amount of the EGR inlet temperature according to the EGR inlet temperature sent by the EGR inlet temperature sensor.
And detecting whether the EGR system has a high-flow fault or not by the vehicle control system according to the temperature rise of the EGR inlet temperature.
In step 202, while the EGR system is operating, it is detected whether a low flow fault has occurred in the EGR system based on the signal value of the knock sensor and the temperature rise of the EGR inlet temperature.
The external EGR system leads the waste gas after the combustion of the engine into the cylinder to participate in the combustion again, so that the combustion temperature in the cylinder is reduced, the oil consumption and the pollutant emission can be reduced to a certain extent by improving the compression ratio and increasing the ignition advance angle, but the increase of the compression ratio and the ignition advance angle also means the increase of the engine knocking risk. When the low flow fault occurs in the EGR system, the vehicle control system still controls the combustion of the mixed gas according to a preset target ignition angle before the vehicle control system reports the low flow fault of the EGR, but at the moment, because the exhaust gas is smaller than the target flow or no exhaust gas enters the cylinder, the temperature in the cylinder is increased compared with the temperature when the low flow fault does not occur in the EGR system, and the engine is easy to knock.
Therefore, in order to improve the detection accuracy of the EGR flow fault, whether the EGR system has a low flow fault is detected by combining the knock sensor signal with the temperature rise of the EGR inlet temperature.
Optionally, the vehicle control system obtains a signal of a knock sensor and a signal of an EGR inlet temperature sensor, and detects whether a low flow fault occurs in the EGR system according to a signal value of the knock sensor and a temperature rise of the EGR inlet temperature.
In summary, according to the EGR flow fault detection method provided in the embodiment of the present application, after the engine is started and before the EGR system operates, whether the EGR system has a high flow fault is detected according to the temperature rise of the EGR inlet temperature, and when the EGR system operates, whether the EGR system has a low flow fault is detected according to the signal value of the knock sensor and the temperature rise of the EGR inlet temperature; the method has the advantages that the flow fault of the EGR system is detected through the knock sensor and the EGR temperature sensor which are configured on the vehicle, so that the problem of low accuracy of the existing EGR flow fault detection is solved; the method and the device have the advantages that the detection cost of the flow faults of the EGR system is reduced, and the detection accuracy of the flow faults of the EGR system is improved.
In addition, a low flow fault is detected through a signal value of the knock sensor, so that the fault can be quickly identified at the initial engine knock stage caused by the low flow fault of the EGR system, and the engine is prevented from being damaged by further knocking.
In an alternative embodiment based on the embodiment shown in fig. 2, the step "after the engine is started and before the EGR system is operated, whether the EGR system has a high flow fault is detected according to the temperature rise amount of the EGR inlet temperature", that is, the step 201 described above, can be implemented as follows:
in step 2011, after the engine is started and before the EGR system is operated, the EGR inlet temperature is obtained and recorded as the first temperature value.
The EGR inlet temperature is obtained by an EGR inlet temperature sensor and recorded as a first temperature value B.
During a high flow fault diagnostic period, a first maximum temperature rise of EGR inlet temperature is obtained.
The time length of the high-flow fault diagnosis period T1 is set in advance.
And acquiring the EGR inlet temperature through the EGR inlet temperature sensor in the high-flow fault diagnosis period T1 by taking the time for recording the first temperature value B as the starting point of the high-flow fault diagnosis period T1, acquiring the maximum value C of the EGR inlet temperature in the high-flow fault diagnosis period T1, and acquiring a first maximum temperature rise amount according to the maximum value C of the EGR inlet temperature in the high-flow fault diagnosis period T1 and the first temperature value B.
It is detected whether the first maximum temperature rise is greater than a first temperature threshold.
A first temperature threshold D is preset.
If the first maximum temperature rise is detected to be larger than a first temperature threshold value, determining that the EGR system has a high-flow fault;
and if the first maximum temperature rise is not larger than the first temperature threshold value, determining that the high flow fault does not occur in the EGR system.
In an alternative embodiment based on the embodiment shown in fig. 2, the step "detecting whether the EGR system has a low flow fault according to the signal value of the knock sensor and the temperature rise of the EGR inlet temperature when the EGR system is operating", that is, the step 202, can be realized by the following steps:
step 2021, detecting whether the EGR system has a low flow fault according to the signal value of the knock sensor when the EGR system is operating, to obtain a first fault flag value.
When the low flow fault of the EGR system is detected according to the signal value of the knock sensor, the first fault flag value indicates that the low flow fault of the EGR system occurs, for example, the first fault flag value M1 is 0; when it is detected that the EGR system has no low flow fault based on the signal value of the knock sensor, the first fault flag value indicates that the EGR system has no low flow fault, such as the first fault flag value M1 being 1.
Optionally, when the EGR system is in operation, the accumulated time of the signal value of the knock sensor in the first low-flow fault diagnosis period being 1 is obtained.
The time length of the first low flow fault diagnosis period T2 is set in advance.
The knock sensor is arranged in an engine block, and the signal value of the knock sensor is 1, which indicates that the engine knocks.
It is detected whether the accumulated time E is greater than a time threshold F.
If the accumulated time E is detected to be larger than the time threshold value F, outputting a first fault flag value M1 indicating that the low flow fault occurs in the EGR system; if the detected accumulated time E is not greater than the time threshold F, a first fault flag value M1 is output indicating that the EGR system has not experienced a low flow fault.
Step 2022, detecting whether the EGR system has a low flow fault according to the temperature rise of the EGR inlet temperature when the EGR system is in operation, and obtaining a second fault flag value.
When the low-flow fault of the EGR system is detected according to the temperature rise amount of the EGR inlet temperature, the second fault flag value indicates that the low-flow fault of the EGR system occurs, for example, the second fault flag value M2 is 0; when it is detected that the low flow fault does not occur in the EGR system according to the temperature rise amount of the EGR inlet temperature, the second fault flag value indicates that the low flow fault does not occur in the EGR system, for example, the second fault flag value M2 is 1.
Optionally, the EGR inlet temperature is obtained and recorded as the second temperature value while the EGR system is operating.
The EGR inlet temperature is obtained by an EGR inlet temperature sensor and recorded as a second temperature value H.
During a second low flow fault diagnostic period, a second maximum temperature rise of EGR inlet temperature is obtained.
The time length of a second low-flow fault diagnosis period T3 is preset, the recording time of a second temperature value H is the starting time of the second low-flow fault diagnosis period T3, the maximum value K of the EGR inlet temperature in the second low-flow fault diagnosis period T3 is obtained, and a second maximum temperature rise of the EGR inlet temperature is obtained according to the second temperature value H and the maximum value K of the EGR inlet temperature in the second low-flow fault diagnosis period T3.
And detecting whether the second maximum temperature rise is greater than a second temperature threshold.
The second temperature threshold L is set in advance.
If the second maximum temperature rise amount is detected to be greater than the second temperature threshold L, a second fault flag value M2, such as M2 ═ 1, indicating that the low flow fault is not occurring in the EGR system is output.
If the second maximum temperature rise amount is detected to be not greater than the second temperature threshold L, a second fault flag value M2, such as M2 0, indicating that the EGR system has a low flow fault is output.
Step 2021 and step 2022 are two independent steps, and step 2021 and step 2022 may be executed simultaneously or not.
And when the first fault flag value and the second fault flag value both indicate that the low-flow fault does not occur in the EGR system, determining that the low-flow fault does not occur in the EGR system.
Such as: when the first fault flag value M1 is equal to 1 and the second fault flag value M2 is equal to 1, it is determined that the low flow fault does not occur in the EGR system.
And when the first fault mark value or the second fault mark value indicates that the low-flow fault occurs in the EGR system, determining that the low-flow fault occurs in the EGR fault system, and stopping detecting the low-flow fault.
For example, if step 2021 is completed and the first fault flag value M1 is obtained as 0, it is determined that the low flow fault occurs in the EGR fault system, and the detection of the low flow fault is stopped; alternatively, when the execution of step 2022 is completed and the second failure flag value M2 is obtained as 0, it is determined that the low flow rate failure has occurred in the EGR failure system, and the detection of the low flow rate failure is stopped.
When the first failure flag value M1 is obtained as 0, even if the second failure flag value is not obtained or the second failure flag value M2 is obtained as 1, it is determined that the low flow fault occurs in the EGR fault system, and the detection of the low flow fault is stopped; likewise, when the second failure flag value M2 is obtained as 0, even if the first failure flag value is not obtained or the first failure flag value M1 is obtained as 1, it is determined that the low flow fault occurs in the EGR fault system, and the detection of the low flow fault is stopped.
Wherein stopping detecting the low flow fault refers to stopping detecting the low flow fault of the EGR system according to the signal value of the knock sensor and stopping detecting the low flow fault of the EGR system according to the temperature rise of the EGR inlet.
In order to make the detection result of the flow fault of the EGR system more accurate, and detect the high flow fault and the low flow fault respectively under the condition that the vehicle system meets the predetermined condition, fig. 3 shows a logic schematic diagram of a flow fault detection method of the EGR system provided by an embodiment of the present application, and the EGR flow fault detection method may include the following steps:
in step 301, after engine start and before the EGR system is operated, when a first predetermined condition is met, EGR inlet temperature is obtained and recorded as a first temperature value.
The EGR inlet temperature is obtained by an EGR inlet temperature sensor and sent to a vehicle control system.
Optionally, the vehicle control system obtains the EGR inlet temperature and records it as a first temperature value B.
In one example, the first predetermined condition is that the temperature value of the turbocharger inlet gas model is greater than a first calibrated temperature threshold.
The temperature of the inlet model of the turbocharger is introduced before the EGR system is operated during engine warm-up to ensure that the temperature of the engine exhaust is sufficiently high, and if the EGR valve has a leak hole, the EGR inlet temperature increases by a large amount as the exhaust flows through the EGR valve.
After the engine is started and before the EGR system works, the vehicle control system obtains a temperature value calculated according to a turbocharger inlet gas model according to a preset period, and detects whether the temperature value of the turbocharger inlet gas model is larger than a first calibration temperature threshold value A or not; when the temperature value calculated by the turbocharger inlet gas model is detected to be larger than a first calibration temperature threshold value A, the condition that a first preset condition is met is shown, and the EGR inlet temperature is obtained and recorded as a first temperature value B.
And if the first preset condition is not met, not performing high-flow fault diagnosis.
The first calibration temperature threshold A is preset, and is determined according to actual conditions.
In step 302, a first maximum temperature increase in EGR inlet temperature is obtained during a high flow fault diagnostic period.
Alternatively, the time length of the high-flow fault diagnosis period T1 is set in advance.
Optionally, in the high-flow fault diagnosis period T1, the EGR inlet temperature is obtained according to a predetermined period, the maximum value C of the EGR inlet temperature in the high-flow fault diagnosis period T1 is determined, and the difference between the maximum value C of the EGR inlet temperature and the first temperature value B is recorded as the first maximum temperature rise Δ T1.
In step 303, it is checked whether the first maximum temperature rise is greater than a first temperature threshold D.
And if the first maximum temperature rise quantity delta t1 is detected to be larger than a first temperature threshold value D, determining that the high-flow fault occurs in the EGR system.
And if the first maximum temperature rise quantity delta t1 is not greater than the first temperature threshold value D, determining that the high flow fault does not occur in the EGR system.
Optionally, after determining that the EGR system has a high-flow fault, the vehicle control system sends a prompt message that the EGR system has the high-flow fault to the in-vehicle display system; if the vehicles are networked, the vehicle control system can also send prompt information that the high-flow fault occurs in the EGR system to the server side.
In step 304, when the second predetermined condition is satisfied while the EGR system is operating, whether the EGR system has a low flow rate fault is detected based on the signal value of the knock sensor, and a first fault flag value M1 is obtained.
Optionally, the second predetermined condition is the EGR target flow being greater than the first flow threshold.
When the EGR system works, the target EGR flow is obtained through a vehicle control system, and whether the target EGR flow is larger than a first flow threshold G1 is detected; and if the EGR target flow is detected to be larger than the first flow threshold G1, detecting whether the low flow fault occurs in the EGR system according to the signal value of the knock sensor, and obtaining a first fault mark value M1.
If the EGR target flow is not larger than the first flow threshold G1, the low flow fault diagnosis of the EGR system is not carried out according to the signal value of the knock sensor.
Whether the EGR system has a low flow fault is detected according to the signal value of the knock sensor to obtain a first fault flag value, which can be realized by the following steps:
when the second predetermined condition is satisfied, the accumulated time E at which the signal value of the knock sensor is 1 within the first low flow fault diagnosis period T2 is acquired.
It is detected whether the accumulated time E is greater than a time threshold F.
If the accumulated time E is detected to be larger than the time threshold F, outputting a first fault flag value M1 indicating that the low flow fault of the EGR system occurs, such as M1 being 0; if the detected accumulated time E is not greater than the time threshold F, a first fault flag value M1, such as M1 ═ 1, is output indicating that the EGR system has not experienced a low flow fault.
This step is illustrated in step 2021 above and will not be described further herein.
Since the first low flow fault diagnosis is detected based on the signal value of the knock sensor, when the first fault flag value indicates that the EGR system has a low flow fault, the engine is controlled to enter a limp home mode and the EGR system is turned off in order to avoid damage to the engine due to knocking.
Note that, in the first low flow rate fault diagnosis period T2, when the second predetermined condition is not satisfied, the low flow rate fault detection of the EGR system based on the signal value of the knock sensor is stopped.
Such as: during the first low flow fault diagnosis period T2, the vehicle control system continuously detects whether the EGR target flow is greater than the first flow threshold G1, and if the EGR target flow is not greater than the first flow threshold G1, the low flow fault detection of the EGR system according to the signal value of the knock sensor is stopped.
In step 305, when the third predetermined condition is satisfied while the EGR system is operating, it is detected whether the EGR system has a low flow rate fault based on the temperature rise amount of the EGR inlet temperature, and a second fault flag value M2 is obtained.
Optionally, the third predetermined condition is the EGR target flow being greater than the second flow threshold.
When the EGR system works, the target EGR flow is obtained through a vehicle control system, and whether the target EGR flow is larger than a second flow threshold G2 is detected; and if the EGR target flow is detected to be larger than the second flow threshold G2, detecting whether the low flow fault occurs in the EGR system according to the temperature rise of the EGR inlet temperature, and obtaining a second fault flag value M2.
If the EGR target flow is detected to be not greater than the second flow threshold G2, then no low flow fault diagnosis is performed for the EGR system based on the amount of temperature rise at the EGR inlet.
Detecting whether the low flow fault occurs in the EGR system according to the temperature rise of the EGR inlet temperature to obtain a second fault flag value, wherein the second fault flag value can be obtained by the following steps:
when a third predetermined condition is met, the EGR inlet temperature is obtained and recorded as a second temperature value H.
And acquiring a second maximum temperature rise quantity delta T2 of the EGR inlet temperature in a second low-flow fault diagnosis period T3.
Alternatively, the time length of the second low flow fault diagnosis period T3 is set in advance.
Optionally, in the second low-flow fault diagnosis period T3, the EGR inlet temperature is obtained according to a predetermined period, the maximum value K of the EGR inlet temperature in the second low-flow fault diagnosis period T3 is determined, and the difference between the maximum value K of the EGR inlet temperature and the first temperature value H is recorded as a second maximum temperature rise amount Δ T2.
And detecting whether the second maximum temperature rise quantity delta t2 is larger than a second temperature threshold value L.
If the second maximum temperature rise Δ t2 is detected to be greater than the second temperature threshold L, a second fault flag value M2 is output, for example, M2 is 1, indicating that the EGR system has not failed at a low flow rate.
If it is detected that the second maximum temperature rise Δ t2 is not greater than the second temperature threshold L, a second fault flag value M2, such as M2 being 0, indicating that the EGR system has a low flow fault is output.
This step is illustrated in step 2022 above and will not be described further herein.
Note that, in the second low flow fault diagnosis period T3, when the third predetermined condition is not satisfied, the low flow fault detection of the EGR system according to the temperature increase amount of the EGR inlet is stopped.
Such as: during a second low flow fault diagnosis period T3, the vehicle control system continuously detects whether the EGR target flow is greater than a second flow threshold G2, and if the EGR target flow is not greater than the second flow threshold G2, the low flow fault detection of the EGR system according to the temperature rise of the EGR inlet is suspended.
It should be noted that step 304 and step 305 are two independent steps, and step 304 and step 305 may be executed simultaneously or not.
And when the first fault flag value and the second fault flag value both indicate that the low-flow fault does not occur in the EGR system, determining that the low-flow fault does not occur in the EGR system.
Such as: when the first fault flag value M1 is equal to 1 and the second fault flag value M2 is equal to 1, it is determined that the low flow fault does not occur in the EGR system.
And when the first fault mark value or the second fault mark value indicates that the low-flow fault occurs in the EGR system, determining that the low-flow fault occurs in the EGR fault system, and stopping detecting the low-flow fault.
For example, if step 304 is completed and the first fault flag value M1 is obtained as 0, it is determined that the low flow fault occurs in the EGR fault system, and the detection of the low flow fault is stopped; alternatively, when the execution of step 305 is completed and the second failure flag value M2 is obtained as 0, it is determined that the low flow rate failure has occurred in the EGR failure system, and the detection of the low flow rate failure is stopped.
When the first failure flag value M1 is obtained as 0, even if the second failure flag value is not obtained or the second failure flag value M2 is obtained as 1, it is determined that the low flow fault occurs in the EGR fault system, and the detection of the low flow fault is stopped; likewise, when the second failure flag value M2 is obtained as 0, even if the first failure flag value is not obtained or the first failure flag value M1 is obtained as 1, it is determined that the low flow fault occurs in the EGR fault system, and the detection of the low flow fault is stopped.
Wherein stopping detecting the low flow fault refers to stopping detecting the low flow fault of the EGR system according to the signal value of the knock sensor and stopping detecting the low flow fault of the EGR system according to the temperature rise of the EGR inlet.
In the EGR flow fault detection method provided by the embodiment of the application, the EGR system is an external EGR system, and the EGR system is a high-pressure EGR system.
Referring to fig. 4, a block diagram of an EGR flow failure detection apparatus according to an exemplary embodiment of the present application is shown. A terminal in the present application may include one or more of the following components: a processor 410 and a memory 420.
Processor 410 may include one or more processing cores. The processor 410 connects various parts within the overall terminal using various interfaces and lines, performs various functions of the terminal and processes data by executing or executing instructions, programs, code sets, or instruction sets stored in the memory 420, and calling data stored in the memory 420. Alternatively, the processor 410 may be implemented in hardware using at least one of Digital Signal Processing (DSP), Field-Programmable Gate Array (FPGA), and Programmable Logic Array (PLA). The processor 410 may integrate one or a combination of a Central Processing Unit (CPU) and a modem. Wherein, the CPU mainly processes an operating system, an application program and the like; the modem is used to handle wireless communications. It is understood that the modem may not be integrated into the processor 410, but may be implemented by a single chip.
Alternatively, the processor 410, when executing program instructions in the memory 420, implements the EGR flow fault detection methods provided by the various method embodiments described above.
The Memory 420 may include a Random Access Memory (RAM) or a Read-Only Memory (Read-Only Memory). Optionally, the memory 420 includes a non-transitory computer-readable medium. The memory 420 may be used to store instructions, programs, code, sets of codes, or sets of instructions. The memory 420 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function, instructions for implementing the various method embodiments described above, and the like; the storage data area may store data created according to the use of the terminal, and the like.
It should be added that the above terminal is only illustrative, and in actual implementation, the terminal may also include fewer or more components, such as: the device further comprises a touch display screen, a communication component, a sensor component and the like, and the embodiment is not limited to one embodiment.
Optionally, the present application further provides a computer readable storage medium, in which a program is stored, the program being loaded and executed by a processor to implement the EGR flow fault detection method of the above method embodiment.
Optionally, the present application further provides a computer product, which includes a computer readable storage medium, in which a program is stored, and the program is loaded and executed by a processor to implement the EGR flow fault detection method of the above method embodiment.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. 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. And obvious variations or modifications of this invention are intended to be covered by the scope of the invention as expressed herein.

Claims (17)

1. A method of EGR flow fault detection, the method comprising:
after the engine is started and before the EGR system works, detecting whether the EGR system has a high-flow fault according to the temperature rise of the EGR inlet temperature;
and when the EGR system works, detecting whether the low flow fault occurs in the EGR system according to the signal value of the knock sensor and the temperature rise of the EGR inlet temperature.
2. The method of claim 1, wherein the detecting whether the EGR system has a high flow fault based on an amount of temperature rise of the EGR inlet temperature comprises:
acquiring EGR inlet temperature and recording as a first temperature value;
acquiring a first maximum temperature rise of the EGR inlet temperature in a high-flow fault diagnosis period;
detecting whether the first maximum temperature rise is greater than a first temperature threshold;
if the first maximum temperature rise is detected to be larger than the first temperature threshold, determining that the EGR system has a high flow fault;
and if the first maximum temperature rise is not larger than the first temperature threshold value, determining that the high flow fault does not occur in the EGR system.
3. The method of claim 2, wherein said obtaining an EGR inlet temperature and noting a first temperature value comprises:
when a first predetermined condition is met, the EGR inlet temperature is obtained and recorded as a first temperature value.
4. The method of claim 3, wherein the first predetermined condition is a temperature value of a turbocharger inlet gas model being greater than a first calibrated temperature threshold.
5. The method of claim 1, wherein detecting whether a low flow fault has occurred in the EGR system based on a signal value of a knock sensor and a temperature rise of the EGR inlet temperature while the EGR system is operating comprises:
when the EGR system works, detecting whether the EGR system has low flow fault or not according to the signal value of the knock sensor to obtain a first fault mark value;
when the EGR system works, detecting whether the low flow fault occurs in the EGR system according to the temperature rise of the EGR inlet temperature to obtain a second fault mark value;
determining that the EGR fault system has no low flow fault when the first fault flag value and the second fault flag value both indicate that the EGR system has no low flow fault;
and when the first fault mark value or the second fault mark value indicates that the low-flow fault occurs in the EGR system, determining that the low-flow fault occurs in the EGR fault system, and stopping detecting the low-flow fault.
6. The method of claim 5, wherein said detecting whether a low flow fault has occurred in said EGR system based on a signal value of said knock sensor, resulting in a first fault flag value, comprises:
and when a second preset condition is met, detecting whether the EGR system has a low flow fault or not according to the signal value of the knock sensor to obtain a first fault mark value.
7. The method of claim 5 or 6, wherein said detecting whether a low flow fault occurs in said EGR system based on a signal value of said knock sensor, resulting in a first fault flag value, comprises:
acquiring accumulated time of a signal value of the knock sensor being 1 in a first low-flow fault diagnosis period;
detecting whether the accumulated time is greater than a time threshold;
if the accumulated time is detected to be larger than the time threshold, outputting a first fault flag value indicating that the low flow fault occurs in the EGR system;
and if the accumulated time is not larger than the time threshold value, outputting a first fault mark value indicating that the low flow fault does not occur in the EGR system.
8. The method of claim 6 or 7, wherein the second predetermined condition is the EGR target flow being greater than a first flow threshold.
9. The method of claim 6, further comprising:
and stopping low flow fault detection of the EGR system according to the signal value of the knock sensor when the second preset condition is not met in the first low flow fault diagnosis period.
10. The method of any of claims 5 to 7, wherein when the first fault flag value indicates a low flow fault with the EGR system, controlling the engine to enter a limp home mode and shutting down the EGR system.
11. The method of claim 5, wherein said detecting whether a low flow fault has occurred in the EGR system based on an amount of temperature rise in the EGR inlet to obtain a second fault flag value comprises:
and when a third preset condition is met, detecting whether the low flow fault occurs in the EGR system according to the temperature rise of the EGR inlet to obtain a second fault mark value.
12. The method of claim 5 or 11, wherein said detecting whether a low flow fault has occurred in the EGR system based on an amount of temperature rise in the EGR inlet temperature, resulting in a second fault flag value, comprises:
acquiring EGR inlet temperature and recording as a second temperature value;
acquiring a second maximum temperature rise of the EGR inlet temperature in a second low-flow fault diagnosis period;
detecting whether the second maximum temperature rise is greater than a second temperature threshold;
if the second maximum temperature rise is detected to be larger than the second temperature threshold, outputting a second fault flag value indicating that the low-flow fault does not occur in the EGR system;
and if the second maximum temperature rise is not larger than the second temperature threshold value, outputting a second fault mark value indicating that the low flow fault occurs in the EGR system.
13. The method of claim 11 or 12, wherein the third predetermined condition is that the EGR target flow is greater than a second flow threshold.
14. The method of claim 11, further comprising:
and in the second low-flow fault diagnosis period, when a third preset condition is not met, stopping low-flow fault detection of the EGR system according to the temperature rise amount of the EGR inlet.
15. The method of any one of claims 1 to 14, wherein the EGR system is an external EGR system.
16. An EGR flow fault detection apparatus, comprising a processor and a memory; stored in the memory is a program that is loaded and executed by the processor to implement the method of any of claims 1 to 15.
17. A computer-readable storage medium, in which a program is stored, which is loaded and executed by a processor to implement the method according to any one of claims 1 to 15.
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