CN113219938A - Flow diagnosis method and system for low-pressure EGR (exhaust gas Recirculation) system of gasoline engine and readable storage medium - Google Patents
Flow diagnosis method and system for low-pressure EGR (exhaust gas Recirculation) system of gasoline engine and readable storage medium Download PDFInfo
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Abstract
The invention discloses a flow diagnosis method and a flow diagnosis system of a low-pressure EGR (exhaust gas recirculation) system of a gasoline engine and a readable storage medium, wherein when the low-flow diagnosis is carried out on the low-pressure EGR system, an engine is continuously operated to a working condition with an EGR rate requirement, the opening state of an EGR valve is detected, if the EGR valve is not opened, a completely blocked low-flow fault is judged to occur, and if the EGR valve is repeatedly opened and closed, a partially blocked low-flow fault is judged to occur; when the high flow diagnosis is carried out on the low-pressure EGR system, the work of the EGR valve is restrained and the mixing valve is opened within the set time of starting the engine, when the opening degree of the mixing valve meets the diagnosis requirement, the temperature of the EGR valve is monitored, and if the temperature change of the EGR valve is larger than the temperature threshold value, the high flow fault is judged to occur. The invention can improve the discrimination of temperature change between a non-fault state and a fault state and the reliability of diagnosis during high-flow diagnosis, and simultaneously diagnoses low-flow faults based on the abnormity of the EGR control system under the working condition with EGR rate requirement, is not influenced by other factors, and is more reliable in diagnosis.
Description
Technical Field
The invention relates to a flow diagnosis technology, in particular to a flow diagnosis method and a flow diagnosis system for a low-pressure EGR (exhaust gas recirculation) system of a gasoline engine and a readable storage medium.
Background
In order to further reduce the consumption and emission of gasoline engines, more and more gasoline engine vehicles are being equipped with external EGR (Exhaust Gas Recirculation) systems, which are further classified into a high pressure EGR system and a low pressure EGR system according to the arrangement structure.
Among them, in a low pressure EGR (LP-EGR) system, as shown in fig. 1, an exhaust gas take-off point a is between two stages of catalysts after a turbine, and an exhaust gas merge point B is at an inlet of a supercharger, resulting in a low pressure at the exhaust gas take-off point of such an EGR system, and thus, it is called a low pressure EGR system. In fig. 1, arrows indicate the flow direction of gas, solid lines indicate air, broken lines indicate a mixture of air and exhaust gas treated by the preceding catalyst, single-dot chain lines indicate exhaust gas generated after combustion, double-dot chain lines indicate exhaust gas treated by the preceding catalyst, and hollow arrows indicate exhaust gas treated by the subsequent catalyst. This system is not enough in the pressure differential between the waste gas is got gas point A and the waste gas and is joined in point B under the condition of well low load (air input), can't directly realize the recirculation of waste gas, consequently sets up a mixing valve before waste gas joins in point A, through the aperture that reduces this mixing valve, can reduce waste gas joins in point B's pressure to the increase waste gas is got the pressure differential of gas point A and waste gas and is joined in point B, realizes the recirculation of waste gas.
The external EGR system can reintroduce the combusted waste gas into the cylinder to participate in the combustion process, so that the pumping loss can be reduced or the compression ratio can be improved to a certain extent by increasing the opening of a throttle valve under the same load, and the emission can be reduced by reducing the temperature in the cylinder in the combustion process and reducing the emission gas (such as NOx) generated under the high-temperature oxygen-rich condition. In view of this, whether the EGR system is operating normally will directly affect the emission results and fuel consumption, and therefore it is necessary to diagnose the major physical failure modes such as high flow failure (blow-by) or low flow failure (clogging) in a timely manner and to reliably report the failure.
Because EGR systems of different engines differ greatly in arrangement and newly added parts, existing diagnostic methods are not universal. At present, methods for diagnosing high and low flow rates of an EGR system of a gasoline engine mainly comprise the following methods:
1) diagnosing the high flow and the low flow of the low-pressure EGR system based on the deviation of the flow calculated by the P/DK and the actually measured flow of an HFM (air mass flow meter);
the method comprises the steps of judging whether high-low flow faults of an EGR system occur or not according to the deviation between a flow calculated by P/DK and an HFM actual measurement flow, specifically, diagnosing under the working condition that an EGR rate (the ratio of the amount of recirculated exhaust gas to the total amount of intake air entering a cylinder) is required, and diagnosing high flow when the EGR rate requirement is low, otherwise, diagnosing low flow when the EGR rate requirement is high; the diagnostic method has the following disadvantages: a) the requirement on the precision of the P/DK calculated flow is high, and the requirement on the precision is generally difficult to meet especially under the low-load working condition, so that the misjudgment probability is increased; b) HFM flow sensors need to be configured;
2) performing high-low flow diagnosis of the EGR system based on the deviation of the rich-lean state of the mixed gas when the EGR works/does not work;
the method is characterized in that whether high-low flow faults of the EGR system occur or not is judged based on the deviation of the rich-lean state of mixed gas when the EGR system works and the rich-lean state of mixed gas when the EGR system does not work, specifically, an average mixed gas concentration value of a period of time is recorded when the EGR system works, then the average mixed gas concentration value of a period of time is recorded when the EGR system does not work, and faults are judged to occur when the difference between the average mixed gas concentration value and the average mixed gas concentration value is larger;
3) diagnosing based on a ratio of an accumulated value of deviation of the target flow rate from the actual flow rate to the accumulated value of the target flow rate;
specifically, when the EGR system is in operation, the deviation between the actual flow and the target flow is accumulated continuously, then a ratio is calculated according to the accumulated deviation and the accumulated target flow, and the ratio is compared with a diagnostic threshold value to judge whether a flow fault occurs.
Disclosure of Invention
The invention aims to provide a flow diagnosis method and system for a low-pressure EGR (exhaust gas recirculation) system of a gasoline engine and a readable storage medium, which can solve the problems that a part or a sensing device with a special structure needs to be configured and the requirement on calculation precision is high in the prior art.
In order to solve the technical problem, the invention provides a flow diagnosis method for a low-pressure EGR system of a gasoline engine, wherein an exhaust gas taking point of the low-pressure EGR system is arranged between two stages of catalysts behind a turbine, an exhaust gas merging point is arranged at an inlet of a supercharger, and exhaust gas collected by the exhaust gas taking point is mixed with air flowing in from a mixing valve at the exhaust gas merging point through an EGR valve and enters the supercharger, wherein:
when low-flow diagnosis is carried out on the low-pressure EGR system, the engine is continuously operated to a working condition with EGR rate requirement, the opening state of the EGR valve is detected, if the EGR valve is not opened, the low-flow fault that the low-pressure EGR system is completely blocked is judged, and if the EGR valve is repeatedly opened and closed, the low-flow fault that the low-pressure EGR system is partially blocked is judged;
and when the high flow diagnosis is carried out on the low-pressure EGR system, the work of the EGR valve is restrained within the set time of engine starting, the mixing valve is opened, when the opening degree of the mixing valve meets the diagnosis requirement, the temperature of the EGR valve is monitored, and if the temperature change of the EGR valve is larger than the temperature threshold value, the high flow fault of the low-pressure EGR system is judged.
Further, the process of low flow diagnosis of the low pressure EGR system includes the steps of:
step S10, judging whether the current working condition meets the detection condition of low flow fault diagnosis, if so, entering step S20 and step S30, otherwise, continuing to execute judgment;
step S20, judging whether the first time parameter is less than the first calibration time, if yes, entering step S21, otherwise entering step S22;
step S21, increasing the first time parameter according to the set step length, and returning to the step S20;
step S22, judging whether the EGR valve is opened within the first calibration time, if so, entering step S23, otherwise, adding 1 to the count value of the low flow fault counter and entering step S23;
step S23, clearing the first time parameter, and entering step S40;
step S30, judging whether the second time parameter is less than the second calibration time, if yes, entering step S31, otherwise entering step S32;
step S31, the second time parameter is increased according to the set step length, and the step S30 is returned;
step S32, judging whether the EGR valve is closed after being opened within the second calibration time, if so, adding 1 to the count value of the low flow fault counter and entering step S33, otherwise, directly entering step S33;
step S33, clearing the second time parameter, and proceeding to step S40;
and step S40, judging whether the count value of the low flow fault counter is greater than or equal to the low flow fault threshold value, if so, reporting that the low flow fault occurs in the low-pressure EGR system, otherwise, returning to the step S10.
Optionally, in step S10, when the current operating condition satisfies the detection condition of low flow fault diagnosis, the method further proceeds to step S50;
step S50, judging whether the third time parameter is smaller than the fault repairing time threshold, if so, entering step S51, otherwise, entering step S52;
step S51, the third time parameter is increased according to the set step length, and the step S50 is returned;
step S52, judging whether the EGR valve is opened within the fault repairing time threshold value and is not closed, if so, adding 1 to the count value of the low flow repairing counter and entering step S53, otherwise, directly entering step S53;
step S53, clearing the third time parameter;
and step S54, judging whether the count value of the low flow rate repair counter is larger than or equal to the low flow rate repair threshold value, if so, reporting low flow rate fault repair, otherwise, returning to the step S10.
Further, the detection condition is that the engine is continuously operated to a condition where an EGR rate is required.
Optionally, the detection conditions include that the rotating speed of the engine reaches a set rotating speed, the torque load reaches a set load, the working condition of the EGR system is enabled, the total charge of the external EGR system is greater than zero, and the EGR rate is greater than an EGR rate threshold value.
Further, the step of performing a high flow diagnostic on the low pressure EGR system is as follows:
step S1, judging whether the EGR valve is opened or not, if so, entering step S2, and if not, ending;
step S2, judging whether the engine start success is met and the EGR temperature is less than the diagnosis threshold value, if so, entering step S3, otherwise, returning to step S1;
step S3, judging whether the current working condition meets the set working condition requirement, if yes, entering step S4, otherwise returning to step S1;
step S4, judging whether the opening degree of the mixing valve is smaller than or equal to a calibrated opening degree threshold value, if so, entering step S5, otherwise, returning to step S1;
step S5, a first flag bit indicating that the operation of the mixing valve meets the high flow diagnosis requirement is set;
step S6, recording the temperature of the EGR valve when the first flag bit is at the rising edge;
step S7, the fourth time parameter is increased according to the set step length;
step S8, judging whether the fourth time parameter is larger than or equal to the third calibration time, if so, entering step S9, otherwise, returning to step S7;
step S9, calculating a temperature change amount of the EGR valve within the third calibration time, and clearing the fourth time parameter;
step S10, judging whether the temperature variation is larger than or equal to the fault temperature threshold, if so, adding 1 to the count value of the high-flow fault counter and entering step S11, otherwise, returning to step S1;
and step S11, judging whether the count value of the high flow fault counter is greater than or equal to a high flow fault threshold value, if so, reporting that the low pressure EGR system has a high flow fault, otherwise, returning to the step S1.
Optionally, in the step S10, when the temperature variation is smaller than the fault temperature threshold, the count value of the high traffic repair counter is incremented by 1, when the count value of the high traffic repair counter is greater than or equal to the high traffic repair threshold, a high traffic fault repair is reported, and when the count value of the high traffic repair counter is smaller than the high traffic repair threshold, the step S1 is returned to.
Optionally, the set operating condition requirements include that high flow diagnosis of the EGR system is not completed, engine starting time is less than or equal to a calibrated time threshold, exhaust temperature reaches a discharge temperature diagnosis threshold, vehicle speed is greater than or equal to a calibrated vehicle speed threshold, and intake air flow is greater than or equal to a calibrated flow threshold.
Optionally, the temperature of the EGR valve is an inlet temperature of the EGR valve.
Optionally, the temperature of the EGR valve is an outlet temperature of the EGR valve.
Optionally, the temperature of the EGR valve is an inlet temperature and an outlet temperature of the EGR valve.
Optionally, the temperature of the EGR valve is the difference between the outlet temperature and the inlet temperature of the EGR valve.
Meanwhile, the invention also provides a flow diagnosis system of the low-pressure EGR system of the gasoline engine, which comprises the following components:
the low-flow diagnosis module is used for detecting the opening state of the EGR valve when the engine continuously runs to a working condition with EGR rate requirement, judging that the low-flow fault of complete blockage occurs in the low-pressure EGR system if the EGR valve is not opened, and judging that the low-flow fault of partial blockage occurs in the low-pressure EGR system if the EGR valve is repeatedly opened and closed;
and the high-flow diagnosis module inhibits the EGR valve from working within the set time of engine starting, opens the mixing valve, monitors the temperature of the EGR valve when the opening degree of the mixing valve meets the diagnosis requirement, and judges that the low-pressure EGR system has a high-flow fault if the temperature change of the EGR valve is greater than a temperature threshold value.
Wherein the low flow diagnostic module comprises:
the first judgment unit is used for judging whether the current working condition meets the detection condition of low-flow fault diagnosis or not, and if so, the first time length judgment unit and the second time length judgment unit are triggered;
the first time length judging unit is used for judging whether the first time parameter is greater than or equal to the first calibration time or not, and if so, the complete blockage judging unit is triggered;
the complete blockage judging unit is used for judging whether the EGR valve is not opened within the first calibration time, and if so, the complete blockage fault alarming unit is triggered;
the complete blockage fault alarm unit is used for reporting a low-flow fault of complete blockage;
the second time length judging unit is used for judging whether the second time parameter is greater than or equal to the second calibration time or not, and if so, the partial blockage judging unit is triggered;
the partial blockage judging unit is used for judging whether the EGR valve is opened within the second calibration time and then closed, and if so, the partial blockage fault alarming unit is triggered;
and the partial blockage fault alarm unit is used for reporting the low flow fault of partial blockage.
Optionally, the low flow diagnostic module further comprises:
the low flow fault counting unit is used for calculating the sum of the times of reporting the low flow fault with the complete blockage by the complete blockage fault alarming unit and the times of reporting the low flow fault with the partial blockage by the partial blockage fault alarming unit;
the low-flow fault judging unit is used for judging whether the counting value of the low-flow fault counting unit is greater than or equal to a low-flow fault threshold value or not, and if so, triggering the low-flow fault alarming unit;
and the low-flow fault alarm unit is used for reporting that the low-flow fault occurs in the low-pressure EGR system.
Optionally, the low flow diagnostic module further comprises:
the third duration judging unit is used for judging whether the third time parameter is greater than or equal to the fault repairing time threshold value or not, and if so, the low flow repairing judging unit is triggered;
the second judgment unit is used for judging whether the EGR valve is opened within the fault restoration time threshold value and is not closed, and if so, reporting that the low flow fault is restored;
and when the judgment result of the first judgment unit is yes, simultaneously triggering a third duration judgment unit.
Optionally, the low flow diagnostic module further comprises:
the low flow rate repair counting unit is used for calculating the times of the low flow rate repair judging unit reporting that the low flow rate fault is repaired;
the low-flow restoration judging unit is used for judging whether the count value of the low-flow restoration counting unit is greater than or equal to a low-flow restoration threshold value or not, and if so, triggering the low-flow restoration prompting unit;
and the low flow recovery prompting unit is used for reporting low flow fault recovery.
Wherein the high flow diagnostic module comprises:
the third judging unit is used for judging whether the EGR valve is opened or not, and if so, the fourth judging unit is triggered;
the fourth judging unit is used for judging whether the engine is successfully started and the EGR temperature is less than the diagnosis threshold value, and if so, the fifth judging unit is triggered;
the fifth judging unit is used for judging whether the current working condition meets the set working condition requirement or not, and if so, the sixth judging unit is triggered;
the mixing valve opening judging unit is used for judging whether the opening of the mixing valve is smaller than or equal to a calibrated opening threshold value or not, and if so, triggering the first processing unit;
a first processing unit which sets a first flag bit indicating that the operation of the mixing valve meets the high-flow diagnosis requirement, records the temperature of the EGR valve when the first flag bit is at a rising edge, and times a fourth time parameter indicating that the operation of the mixing valve meets the high-flow diagnosis requirement;
the fourth time length judging unit is used for judging whether the fourth time parameter is greater than or equal to the third calibration time or not, and if so, triggering the second processing unit;
a second processing unit that calculates a temperature change amount of the EGR valve in a time period indicated by the fourth time parameter, and clears the fourth time parameter to zero;
and the temperature change judging unit is used for judging whether the temperature change is greater than or equal to a fault temperature threshold value or not, and if so, reporting that a high-flow fault occurs.
Optionally, the high flow diagnostic module further comprises:
the high-flow fault counting unit is used for calculating the frequency of the high-flow faults reported by the temperature change judging unit;
the high-flow fault judging unit is used for judging whether the counting value of the high-flow fault counting unit is greater than or equal to a high-flow fault threshold value or not, and if so, triggering the high-flow fault alarming unit;
and the high-flow fault alarm unit is used for reporting that the low-pressure EGR system has high-flow faults.
Optionally, the high flow diagnostic module further comprises:
the high-flow restoration counting unit is used for adding 1 to the counting value of the high-flow restoration counting unit when the temperature change judging unit judges that the temperature change is smaller than the fault temperature threshold;
the high-flow restoration judging unit is used for judging whether the count value of the high-flow restoration counting unit is greater than or equal to a high-flow restoration threshold value or not, and if so, triggering the high-flow restoration prompting unit;
and the high-flow restoration prompting unit is used for reporting high-flow failure restoration.
Optionally, the temperature of the EGR valve recorded by the first processing unit is any one of an inlet temperature of the EGR valve, an outlet temperature of the EGR valve, an inlet-outlet temperature of the EGR valve, an outlet temperature of the EGR valve, and a temperature difference between the inlet temperature and the outlet temperature of the EGR valve.
Furthermore, the present invention also provides a readable storage medium, on which at least one instruction or program is stored, the instruction or program being loaded by the processor and executing the optimization method capable of being described above.
Compared with the prior art, the invention has the beneficial effects that:
firstly, whether a low-flow fault occurs or not is diagnosed by judging whether the EGR control is abnormal or not in a working condition with an EGR rate requirement, the diagnosis mode is basically not influenced by other factors, and the diagnosis result is more reliable;
secondly, the high-flow fault diagnosis of the invention inhibits the work of the EGR valve within a period of time after the engine is started, and ensures that the temperature of the EGR valve has larger rising amount when the low-pressure EGR system has high-flow fault by combining the throttling function of the mixing valve, thereby improving the discrimination of temperature change under the non-fault state and the fault state and improving the reliability of diagnosis;
thirdly, the flow diagnosis method of the invention does not need to additionally arrange a flow sensor and an EGR valve with a special structure, and the diagnosis precision is not influenced by other factors, thus the application range is wider.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a low pressure EGR system;
FIG. 2 is a schematic diagram of a first apparatus for flow diagnosis of a medium-low pressure EGR system according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a second apparatus for flow diagnosis of a medium-low pressure EGR system according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a third apparatus for flow diagnosis of a medium-low pressure EGR system in accordance with an embodiment of the present invention;
FIG. 5 is a flowchart of a method for diagnosing low flow rate faults in a low-medium pressure EGR system according to a second embodiment of the present invention;
FIG. 6 is a flowchart of a method for diagnosing a high flow fault in a low-medium pressure EGR system according to a second embodiment of the present invention;
FIG. 7 is a block diagram of a low flow diagnostic module of the flow diagnostic system of the medium and low pressure EGR system according to a second embodiment of the present invention;
FIG. 8 is a block diagram of another low flow diagnostic module of the flow diagnostic system of the medium and low pressure EGR system according to the second embodiment of the present invention;
FIG. 9 is a block diagram of a high flow diagnostic module of the flow diagnostic system of the medium and low pressure EGR system according to a second embodiment of the present invention;
FIG. 10 is a block diagram of another structure of a high flow diagnostic module of the flow diagnostic system of the medium and low pressure EGR system according to the second embodiment of the present invention;
FIG. 11 is a flowchart of a method for low flow fault recovery and diagnosis of a low-medium pressure EGR system in accordance with a third embodiment of the present invention;
FIG. 12 is a block diagram of a low flow diagnostic module of a flow diagnostic system of a medium and low pressure EGR system according to a third embodiment of the present invention;
fig. 13 is a block diagram of a high flow diagnostic module of the flow diagnostic system of the middle and low pressure EGR system according to the fourth embodiment of the present invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and technical effects of the present invention will be fully apparent to those skilled in the art from the disclosure in the specification. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. The invention is capable of other embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the general spirit of the invention. It should be noted that, in the following embodiments, technical features may be combined with each other without conflict.
Furthermore, it will be understood that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer program instructions. It is well known to those skilled in the art that implementation by hardware, by software, and by a combination of software and hardware are equivalent.
Example one
In order to overcome the defects of a high-low flow diagnosis method of an EGR system in the prior art, the invention provides a flow diagnosis method of a low-pressure EGR system of a gasoline engine, wherein:
when low-flow diagnosis is carried out on the low-pressure EGR system, the engine is continuously operated to a working condition with EGR rate requirement, the opening state of the EGR valve is detected, if the EGR valve is not opened, the low-flow fault that the low-pressure EGR system is completely blocked is judged, and if the EGR valve is repeatedly opened and closed, the low-flow fault that the low-pressure EGR system is partially blocked is judged;
and when the high flow diagnosis is carried out on the low-pressure EGR system, the work of the EGR valve is restrained within the set time of engine starting, the mixing valve is opened, when the opening degree of the mixing valve meets the diagnosis requirement, the temperature of the EGR valve is monitored, and if the temperature change of the EGR valve is larger than the temperature threshold value, the high flow fault of the low-pressure EGR system is judged.
The exhaust gas intake point A of the low-pressure EGR system is arranged between two stages of catalysts behind a turbine, the exhaust gas intake point B is arranged at an inlet of the supercharger, and the exhaust gas collected by the exhaust gas intake point A passes through the EGR valve to be mixed with the air flowing in from the mixing valve and enters the supercharger.
The principle of the low flow (clogging) fault diagnosis described above is mainly based on whether or not the EGR control is abnormal. Low flow (blockage) failures can be classified into full blockage and partial blockage depending on the degree of blockage. Since the opening of the EGR valve is controlled based on the deviation of the target flow rate from the actual flow rate, which is calculated based on the differential pressure across the EGR valve, the control system constantly adjusts the opening of the EGR valve to ensure that the actual flow rate is consistent with the target flow rate. If a blockage fault (an EGR valve or a pipeline) occurs, the blockage can cause the front-back pressure difference of the EGR valve to be too small, at the moment, the control system can adjust the opening degree of the EGR valve to the large direction, the larger the opening degree of the EGR valve is, the smaller the front-back pressure difference of the EGR valve is, and when the front-back pressure difference is lower than a set threshold value (the front-back pressure ratio is larger than the set threshold value), the EGR valve is triggered to be closed. For the condition of complete blockage, the front-back pressure ratio is 1 or close to 1, when the engine continuously operates to a working condition with an EGR rate requirement, the EGR is not opened due to the fact that the pressure ratio is not met, and then the occurrence of complete blockage faults can be diagnosed. In the case of partial blockage, when the engine is continuously operated to a working condition with an EGR rate requirement, the EGR valve is repeatedly opened and closed due to the adjustment of the system, and then the partial blockage fault can be diagnosed.
In the high flow diagnostic described above, the temperature of the EGR valve may be selected in a variety of ways. For example, in one embodiment, as shown in fig. 2, a temperature sensor is disposed at the inlet of the EGR valve, the temperature sensor is used to monitor the inlet temperature of the EGR valve, when the inlet temperature change of the EGR valve is greater than a temperature threshold, it is indicated that the inlet temperature of the EGR valve is increased due to air leakage from the EGR valve, and it is determined that a high flow rate fault occurs.
In another embodiment, as shown in fig. 3, a temperature sensor is arranged at the outlet of the EGR valve, the outlet temperature of the EGR valve is monitored by using the temperature sensor, when the outlet temperature change of the EGR valve is larger than a temperature threshold value, the outlet temperature of the EGR valve is increased due to air leakage of the EGR valve, and the high flow fault is determined to occur.
In another embodiment, temperature sensors may be further disposed at both the inlet and the outlet of the EGR valve, while monitoring the inlet temperature and the outlet temperature of the EGR valve, and when the inlet temperature change and/or the outlet temperature change of the EGR valve are greater than a temperature threshold, indicating that the EGR valve leaks air, resulting in an increase in the outlet/inlet temperature of the EGR valve, determining that a high-flow fault has occurred.
In another embodiment, as shown in FIG. 4, temperature sensors are provided at both the inlet and outlet of the EGR valve, while the inlet and outlet temperatures of the EGR valve are monitored, and the differential temperature changes between the outlet and inlet temperatures are used for diagnostics. When the temperature difference change of the EGR valve is larger than the set temperature difference threshold value, the air leakage of the EGR valve is indicated, the temperature of the inlet/outlet of the EGR valve is increased, and the high-flow fault is judged.
The above-described high-flow (blow-by) fault diagnosis principle is mainly based on a temperature change of the EGR valve. The method comprises the steps of inhibiting the EGR valve from working within a period of time after the engine is started, opening the mixing valve, monitoring the change condition of the EGR temperature when the opening degree of the mixing valve meets a diagnosis requirement (a set opening degree threshold), and diagnosing a high-flow (gas leakage) fault if the temperature change is larger than the temperature threshold, which shows that the EGR valve has gas leakage and the temperature of the EGR valve rises. In the diagnosis process, the throttling function of the mixing valve is also utilized, so that enough pressure difference can be generated before and after the EGR valve under low load, and therefore when high-flow fault occurs, the temperature of the inlet/outlet of the EGR valve has enough rising amount, and the reliability of diagnosis is guaranteed.
The flow diagnosis system realized based on the flow diagnosis method comprises a low flow diagnosis module and a high flow diagnosis module, wherein:
the low flow diagnosis module is used for detecting the opening state of the EGR valve when the engine continuously runs to a working condition with EGR rate requirement, judging that the low flow fault of the low pressure EGR system is completely blocked if the EGR valve is not opened, and judging that the low flow fault of partial blockage occurs in the low pressure EGR system if the EGR valve is repeatedly opened and closed;
the high-flow diagnosis module inhibits the EGR valve from working within the set time of engine starting, opens the mixing valve, monitors the temperature of the EGR valve when the opening degree of the mixing valve meets the diagnosis requirement, and judges that the low-pressure EGR system has a high-flow fault if the temperature change of the EGR valve is larger than a temperature threshold value.
Wherein, the EGR rate (target threshold value of the EGR rate) required by the working condition of continuous work of the engine in the low flow diagnosis can be set according to actual needs of different projects.
According to the method, whether the low-flow fault occurs or not is diagnosed by judging whether the EGR control is abnormal or not in the working condition with the EGR rate requirement, the diagnosis mode is basically not influenced by other factors, and the diagnosis result is more reliable; the high-flow fault diagnosis is to inhibit the EGR valve from working within a period of time after the engine is started, and then ensures that the temperature of the EGR valve has larger rising amount when the low-pressure EGR system has high-flow fault by combining the throttling function of the mixing valve, thereby improving the discrimination of temperature change under the non-fault state and the fault state and improving the reliability of diagnosis.
In addition, the flow diagnosis method of the embodiment does not need to additionally arrange a flow sensor and an EGR valve with a special structure, the diagnosis precision is not influenced by other factors, and the application range is wider.
Example two
On the basis of the first embodiment, the present embodiment further describes specific implementations of the low flow rate diagnosis and the high flow rate diagnosis.
The process of performing the low flow diagnosis on the low pressure EGR system, as shown in fig. 5, includes the following steps:
step S10, judging whether the current working condition meets the detection condition of low flow fault diagnosis, if so, entering step S20 and step S30, otherwise, continuing to execute judgment;
step S20, judging whether the first time parameter is less than the first calibration time, if yes, entering step S21, otherwise entering step S22;
step S21, increasing the first time parameter according to the set step length, and returning to the step S20;
step S22, judging whether the EGR valve is opened within the first calibration time, if so, entering step S23, otherwise, adding 1 to the count value of the low flow fault counter and entering step S23;
step S23, clearing the first time parameter, and entering step S40;
step S30, judging whether the second time parameter is less than the second calibration time, if yes, entering step S31, otherwise entering step S32;
step S31, the second time parameter is increased according to the set step length, and the step S30 is returned;
step S32, judging whether the EGR valve is closed after being opened within the second calibration time, if so, adding 1 to the count value of the low flow fault counter and entering step S33, otherwise, directly entering step S33;
step S33, clearing the second time parameter, and proceeding to step S40;
and step S40, judging whether the count value of the low flow fault counter is greater than or equal to the low flow fault threshold value, if so, reporting that the low flow fault occurs in the low-pressure EGR system, otherwise, returning to the step S10.
Wherein the detection condition is that the engine is continuously operated to a working condition with an EGR rate requirement.
Further, the detection conditions comprise that the rotating speed of the engine reaches a set rotating speed, the torque load reaches a set load, the working condition of the EGR system is enabled, the total charge of the external EGR system is larger than zero, and the EGR rate is larger than an EGR rate threshold value.
Meanwhile, as shown in fig. 6, the step of performing the high flow rate diagnosis on the low pressure EGR system is as follows:
step S1, judging whether the EGR valve is not opened, if so, entering step S2, otherwise, ending;
step S2, judging whether the engine start success is met and the EGR temperature is less than the diagnosis threshold value, if so, entering step S3, otherwise, returning to step S1;
step S3, judging whether the current working condition meets the set working condition requirement, if yes, entering step S4, otherwise returning to step S1;
step S4, judging whether the opening degree of the mixing valve is smaller than or equal to a calibrated opening degree threshold value, if so, entering step S5, otherwise, returning to step S1;
step S5, a first flag bit indicating that the operation of the mixing valve meets the high flow diagnosis requirement is set;
step S6, recording the temperature of the EGR valve when the first flag bit is at the rising edge;
step S7, the fourth time parameter is increased according to the set step length;
step S8, judging whether the fourth time parameter is larger than or equal to the third calibration time, if so, entering step S9, otherwise, returning to step S7;
step S9, calculating a temperature change amount of the EGR valve within the third calibration time (i.e., a difference between the temperature of the EGR valve increased within the third calibration time and the temperature of the EGR valve at the time when the first flag is at the rising edge in step S6), and clearing the fourth time parameter;
step S10, judging whether the temperature variation is larger than or equal to the fault temperature threshold, if so, adding 1 to the count value of the high-flow fault counter and entering step S11, otherwise, returning to step S1;
and step S11, judging whether the count value of the high flow fault counter is greater than or equal to a high flow fault threshold value, if so, reporting that the low pressure EGR system has a high flow fault, otherwise, returning to the step S1.
The set working condition requirements comprise that high flow diagnosis of the EGR system is not completed, the starting time of the engine is less than or equal to a calibration time threshold, the exhaust temperature reaches a discharge temperature diagnosis threshold, the vehicle speed is greater than or equal to a calibration vehicle speed threshold, and the intake flow is greater than or equal to a calibration flow threshold.
Based on the specific steps of the low flow fault diagnosis, as shown in fig. 7, the low flow diagnosis module in the flow diagnosis system of this embodiment includes:
the first judgment unit is used for judging whether the current working condition meets the detection condition of low-flow fault diagnosis or not, and if so, the first time length judgment unit and the second time length judgment unit are triggered;
the first time length judging unit is used for judging whether the first time parameter is greater than or equal to the first calibration time or not, and if so, the complete blockage judging unit is triggered;
the complete blockage judging unit is used for judging whether the EGR valve is not opened within the first calibration time, and if so, the complete blockage fault alarming unit is triggered;
the complete blockage fault alarm unit is used for reporting a low-flow fault of complete blockage;
the second time length judging unit is used for judging whether the second time parameter is greater than or equal to the second calibration time or not, and if so, the partial blockage judging unit is triggered;
the partial blockage judging unit is used for judging whether the EGR valve is opened within the second calibration time and then closed, and if so, the partial blockage fault alarming unit is triggered;
and the partial blockage fault alarm unit is used for reporting the low flow fault of partial blockage.
Furthermore, the method can also carry out statistic alarm on the occurrence frequency of the low-flow fault, thereby being capable of diagnosing the occurrence of the fault more accurately and avoiding accidental accidents. As shown in fig. 8, the low flow diagnostic module of the present embodiment further includes:
the low flow fault counting unit is used for calculating the sum of the times of reporting the low flow fault with the complete blockage by the complete blockage fault alarming unit and the times of reporting the low flow fault with the partial blockage by the partial blockage fault alarming unit;
the low-flow fault judging unit is used for judging whether the counting value of the low-flow fault counting unit is greater than or equal to a low-flow fault threshold value or not, and if so, triggering the low-flow fault alarming unit;
and the low-flow fault alarm unit is used for reporting that the low-flow fault occurs in the low-pressure EGR system.
Based on the specific steps of the high-flow fault diagnosis, as shown in fig. 9, the high-flow diagnosis module in the flow diagnosis system of this embodiment includes:
the third judging unit is used for judging whether the EGR valve is not opened or not, and if so, the fourth judging unit is triggered;
the fourth judging unit is used for judging whether the engine is successfully started and the EGR temperature is less than the diagnosis threshold value, and if so, the fifth judging unit is triggered;
the fifth judging unit is used for judging whether the current working condition meets the set working condition requirement or not, and if so, the sixth judging unit is triggered;
the mixing valve opening judging unit is used for judging whether the opening of the mixing valve is smaller than or equal to a calibrated opening threshold value or not, and if so, triggering the first processing unit;
a first processing unit which sets a first flag bit indicating that the operation of the mixing valve meets the high-flow diagnosis requirement, records the temperature of the EGR valve when the first flag bit is at a rising edge, and times a fourth time parameter indicating that the operation of the mixing valve meets the high-flow diagnosis requirement;
the fourth time length judging unit is used for judging whether the fourth time parameter is greater than or equal to the third calibration time or not, and if so, triggering the second processing unit;
a second processing unit that calculates a temperature change amount of the EGR valve in a time period indicated by the fourth time parameter, and clears the fourth time parameter to zero;
and the temperature change judging unit is used for judging whether the temperature change is greater than or equal to a fault temperature threshold value or not, and if so, reporting that a high-flow fault occurs.
Wherein the temperature of the EGR valve recorded by the first processing unit is any one of an inlet temperature of the EGR valve, an outlet temperature of the EGR valve, an inlet and outlet temperature of the EGR valve, and a temperature difference between the outlet temperature and the inlet temperature of the EGR valve.
Likewise, as shown in fig. 10, the high flow diagnostic module further includes:
the high-flow fault counting unit is used for calculating the frequency of the high-flow faults reported by the temperature change judging unit;
the high-flow fault judging unit is used for judging whether the counting value of the high-flow fault counting unit is greater than or equal to a high-flow fault threshold value or not, and if so, triggering the high-flow fault alarming unit;
and the high-flow fault alarm unit is used for reporting that the low-pressure EGR system has high-flow faults.
EXAMPLE III
On the basis of the second embodiment, the flow diagnosis method and the flow diagnosis system of the embodiment further cover the repair diagnosis function of the low-flow fault, so that whether the low-flow fault is repaired or not can be accurately judged.
Specifically, as shown in fig. 11, the low fault repairing and diagnosing steps in the low flow fault diagnosing process are as follows:
in step S10, when the current operating condition satisfies the detection condition of low flow fault diagnosis, the method also proceeds to step S50;
step S50, judging whether the third time parameter is smaller than the fault repairing time threshold, if so, entering step S51, otherwise, entering step S52;
step S51, the third time parameter is increased according to the set step length, and the step S50 is returned;
step S52, judging whether the EGR valve is opened within the fault repairing time threshold value and is not closed, if so, adding 1 to the count value of the low flow repairing counter and entering step S53, otherwise, directly entering step S53;
step S53, clearing the third time parameter;
and step S54, judging whether the count value of the low flow rate repair counter is larger than or equal to the low flow rate repair threshold value, if so, reporting low flow rate fault repair, otherwise, returning to the step S10.
It should be noted that the above steps are also executed when there is no fault, that is, the fault-free diagnosis is completed. And after the low-flow fault is eliminated, the steps are executed to finish the fault repairing judgment.
On the basis of the above-mentioned low fault recovery diagnosis procedure, as shown in fig. 12, the low flow diagnosis module further includes:
the third duration judging unit is used for judging whether the third time parameter is greater than or equal to the fault repairing time threshold value or not, and if so, the low flow repairing judging unit is triggered;
the second judgment unit is used for judging whether the EGR valve is opened within the fault restoration time threshold value and is not closed, and if so, reporting that the low flow fault is restored;
and when the judgment result of the first judgment unit is yes, simultaneously triggering a third duration judgment unit.
Further, the low flow diagnostic module further comprises:
the low flow rate repair counting unit is used for calculating the times of the low flow rate repair judging unit reporting that the low flow rate fault is repaired;
the low-flow restoration judging unit is used for judging whether the count value of the low-flow restoration counting unit is greater than or equal to a low-flow restoration threshold value or not, and if so, triggering the low-flow restoration prompting unit;
and the low flow recovery prompting unit is used for reporting low flow fault recovery.
Example four
On the basis of the second embodiment, the flow diagnosis method and the flow diagnosis system of the embodiment further cover the repair diagnosis function of the high-flow fault, so that whether the high-flow fault is repaired or not can be accurately judged.
As shown in fig. 6, in step S10, when the temperature change amount is smaller than the failure temperature threshold, the count value of the high traffic volume repair counter is incremented by 1, when the count value of the high traffic volume repair counter is greater than or equal to the high traffic volume repair threshold, a high traffic volume failure repair is reported, and when the count value of the high traffic volume repair counter is smaller than the high traffic volume repair threshold, the process returns to step S1.
Correspondingly, as shown in fig. 13, the high flow diagnostic module further includes:
the high-flow restoration counting unit is used for adding 1 to the counting value of the high-flow restoration counting unit when the temperature change judging unit judges that the temperature change is smaller than the fault temperature threshold;
the high-flow restoration judging unit is used for judging whether the count value of the high-flow restoration counting unit is greater than or equal to a high-flow restoration threshold value or not, and if so, triggering the high-flow restoration prompting unit;
and the high-flow restoration prompting unit is used for reporting high-flow failure restoration.
Based on the foregoing embodiments, an embodiment of the present invention further provides a readable storage medium, where at least one instruction or program is stored, and the instruction or program is loaded by the processor and executes the optimization method that can implement any of the foregoing embodiments.
These computer programs may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the programs, which execute via the processor of the computer or other programmable data processing apparatus, implement the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer programs may also be stored in a readable storage medium that can direct a computer, programmable data processing apparatus, and/or other devices to function in a particular manner. The computer program may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the computer program which executes on the computer, other programmable apparatus or other devices implements the functions/acts specified in the flowchart and/or block diagram block or blocks.
The present invention has been described in detail with reference to the specific embodiments, which are merely preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Equivalent alterations and modifications of the above-described elements by those skilled in the art should be considered to be within the scope of the invention as hereinafter claimed, without departing from the principles of the invention.
Claims (22)
1. A flow diagnosis method for a low-pressure EGR system of a gasoline engine, wherein an exhaust gas taking point of the low-pressure EGR system is arranged between two stages of catalysts behind a turbine, an exhaust gas merging point is arranged at an inlet of a supercharger, and exhaust gas collected by the exhaust gas taking point passes through an EGR valve, is mixed with air flowing in from a mixing valve at the exhaust gas merging point and enters the supercharger,
when low-flow diagnosis is carried out on the low-pressure EGR system, the engine is continuously operated to a working condition with EGR rate requirement, the opening state of the EGR valve is detected, if the EGR valve is not opened, the low-flow fault that the low-pressure EGR system is completely blocked is judged, and if the EGR valve is repeatedly opened and closed, the low-flow fault that the low-pressure EGR system is partially blocked is judged;
and when the high flow diagnosis is carried out on the low-pressure EGR system, the work of the EGR valve is restrained within the set time of engine starting, the mixing valve is opened, when the opening degree of the mixing valve meets the diagnosis requirement, the temperature of the EGR valve is monitored, and if the temperature change of the EGR valve is larger than the temperature threshold value, the high flow fault of the low-pressure EGR system is judged.
2. The flow rate diagnosis method of a low pressure EGR system of a gasoline engine according to claim 1, wherein the process of low flow rate diagnosis for the low pressure EGR system comprises the steps of:
step S10, judging whether the current working condition meets the detection condition of low flow fault diagnosis, if so, entering step S20 and step S30, otherwise, continuing to execute judgment;
step S20, judging whether the first time parameter is less than the first calibration time, if yes, entering step S21, otherwise entering step S22;
step S21, increasing the first time parameter according to the set step length, and returning to the step S20;
step S22, judging whether the EGR valve is opened within the first calibration time, if so, entering step S23, otherwise, adding 1 to the count value of the low flow fault counter and entering step S23;
step S23, clearing the first time parameter, and entering step S40;
step S30, judging whether the second time parameter is less than the second calibration time, if yes, entering step S31, otherwise entering step S32;
step S31, the second time parameter is increased according to the set step length, and the step S30 is returned;
step S32, judging whether the EGR valve is closed after being opened within the second calibration time, if so, adding 1 to the count value of the low flow fault counter and entering step S33, otherwise, directly entering step S33;
step S33, clearing the second time parameter, and proceeding to step S40;
and step S40, judging whether the count value of the low flow fault counter is greater than or equal to the low flow fault threshold value, if so, reporting that the low flow fault occurs in the low-pressure EGR system, otherwise, returning to the step S10.
3. The flow rate diagnosis method of a low pressure EGR system of a gasoline engine according to claim 2, characterized in that in step S10, when the current operating condition satisfies the detection condition of low flow rate fault diagnosis, the flow rate diagnosis further proceeds to step S50;
step S50, judging whether the third time parameter is smaller than the fault repairing time threshold, if so, entering step S51, otherwise, entering step S52;
step S51, the third time parameter is increased according to the set step length, and the step S50 is returned;
step S52, judging whether the EGR valve is opened within the fault repairing time threshold value and is not closed, if so, adding 1 to the count value of the low flow repairing counter and entering step S53, otherwise, directly entering step S53;
step S53, clearing the third time parameter;
and step S54, judging whether the count value of the low flow rate repair counter is larger than or equal to the low flow rate repair threshold value, if so, reporting low flow rate fault repair, otherwise, returning to the step S10.
4. The flow diagnostic method of a low-pressure EGR system of a gasoline engine according to claim 2 or 3, characterized in that the detection condition is that the engine is continuously operated to a condition requiring an EGR rate.
5. The flow diagnostic method for a low pressure EGR system of a gasoline engine as recited in claim 4, wherein the detection conditions include engine speed reaching a set speed, torque load reaching a set load, EGR system operating condition enabling, total external EGR system charge greater than zero, and EGR rate greater than an EGR rate threshold.
6. The flow rate diagnosis method of a low pressure EGR system of a gasoline engine according to claim 1, wherein the step of performing the high flow rate diagnosis for the low pressure EGR system is as follows:
step S1, judging whether the EGR valve is not opened, if so, entering step S2, otherwise, ending;
step S2, judging whether the engine start success is met and the EGR temperature is less than the diagnosis threshold value, if so, entering step S3, otherwise, returning to step S1;
step S3, judging whether the current working condition meets the set working condition requirement, if yes, entering step S4, otherwise returning to step S1;
step S4, judging whether the opening degree of the mixing valve is smaller than or equal to a calibrated opening degree threshold value, if so, entering step S5, otherwise, returning to step S1;
step S5, a first flag bit indicating that the operation of the mixing valve meets the high flow diagnosis requirement is set;
step S6, recording the temperature of the EGR valve when the first flag bit is at the rising edge;
step S7, the fourth time parameter is increased according to the set step length;
step S8, judging whether the fourth time parameter is larger than or equal to the third calibration time, if so, entering step S9, otherwise, returning to step S7;
step S9, calculating a temperature change amount of the EGR valve within the third calibration time, and clearing the fourth time parameter;
step S10, judging whether the temperature variation is larger than or equal to the fault temperature threshold, if so, adding 1 to the count value of the high-flow fault counter and entering step S11, otherwise, returning to step S1;
and step S11, judging whether the count value of the high flow fault counter is greater than or equal to a high flow fault threshold value, if so, reporting that the low pressure EGR system has a high flow fault, otherwise, returning to the step S1.
7. The flow rate diagnosis method for a low pressure EGR system of a gasoline engine according to claim 6, wherein in the step S10, when the temperature variation is smaller than the fault temperature threshold, the count value of a high flow rate repair counter is increased by 1, when the count value of the high flow rate repair counter is greater than or equal to a high flow rate repair threshold, a high flow rate fault repair is reported, and when the count value of the high flow rate repair counter is smaller than a high flow rate repair threshold, the flow rate diagnosis returns to the step S1.
8. The flow diagnostic method of a low-pressure EGR system of a gasoline engine as recited in claim 6, wherein the set operating condition requirements include that high flow diagnosis of the EGR system is not completed, engine start time is less than or equal to a calibrated time threshold, exhaust temperature reaches a discharge temperature diagnostic threshold, vehicle speed is greater than or equal to a calibrated vehicle speed threshold, and intake air flow is greater than or equal to a calibrated flow threshold.
9. The flow diagnostic method of a low pressure EGR system for a gasoline engine according to claim 1, 6 or 7, characterized in that the temperature of the EGR valve is the inlet temperature of the EGR valve.
10. The flow diagnostic method of a low pressure EGR system for a gasoline engine according to claim 1, 6 or 7, characterized in that the temperature of the EGR valve is the outlet temperature of the EGR valve.
11. The flow diagnostic method of a low pressure EGR system for a gasoline engine according to claim 1, 6 or 7, characterized in that the temperature of the EGR valve is the inlet temperature and the outlet temperature of the EGR valve.
12. The flow diagnostic method of a low pressure EGR system of a gasoline engine according to claim 1, 6 or 7, characterized in that the temperature of the EGR valve is a temperature difference between an outlet temperature and an inlet temperature of the EGR valve.
13. A flow diagnostic system of a low-pressure EGR system of a gasoline engine is characterized by comprising the following components:
the low-flow diagnosis module is used for detecting the opening state of the EGR valve when the engine continuously runs to a working condition with EGR rate requirement, judging that the low-flow fault of complete blockage occurs in the low-pressure EGR system if the EGR valve is not opened, and judging that the low-flow fault of partial blockage occurs in the low-pressure EGR system if the EGR valve is repeatedly opened and closed;
and the high-flow diagnosis module inhibits the EGR valve from working within the set time of engine starting, opens the mixing valve, monitors the temperature of the EGR valve when the opening degree of the mixing valve meets the diagnosis requirement, and judges that the low-pressure EGR system has a high-flow fault if the temperature change of the EGR valve is greater than a temperature threshold value.
14. The flow diagnostic system of a gasoline engine low pressure EGR system of claim 13, wherein the low flow diagnostic module comprises:
the first judgment unit is used for judging whether the current working condition meets the detection condition of low-flow fault diagnosis or not, and if so, the first time length judgment unit and the second time length judgment unit are triggered;
the first time length judging unit is used for judging whether the first time parameter is greater than or equal to the first calibration time or not, and if so, the complete blockage judging unit is triggered;
the complete blockage judging unit is used for judging whether the EGR valve is not opened within the first calibration time, and if so, the complete blockage fault alarming unit is triggered;
the complete blockage fault alarm unit is used for reporting a low-flow fault of complete blockage;
the second time length judging unit is used for judging whether the second time parameter is greater than or equal to the second calibration time or not, and if so, the partial blockage judging unit is triggered;
the partial blockage judging unit is used for judging whether the EGR valve is opened within the second calibration time and then closed, and if so, the partial blockage fault alarming unit is triggered;
and the partial blockage fault alarm unit is used for reporting the low flow fault of partial blockage.
15. The flow diagnostic system for a low pressure EGR system for a gasoline engine of claim 14 wherein said low flow diagnostic module further comprises:
the low flow fault counting unit is used for calculating the sum of the times of reporting the low flow fault with the complete blockage by the complete blockage fault alarming unit and the times of reporting the low flow fault with the partial blockage by the partial blockage fault alarming unit;
the low-flow fault judging unit is used for judging whether the counting value of the low-flow fault counting unit is greater than or equal to a low-flow fault threshold value or not, and if so, triggering the low-flow fault alarming unit;
and the low-flow fault alarm unit is used for reporting that the low-flow fault occurs in the low-pressure EGR system.
16. The flow diagnostic system for a low pressure EGR system for a gasoline engine of claim 15 wherein said low flow diagnostic module further comprises:
the third duration judging unit is used for judging whether the third time parameter is greater than or equal to the fault repairing time threshold value or not, and if so, the low flow repairing judging unit is triggered;
the second judgment unit is used for judging whether the EGR valve is opened within the fault restoration time threshold value and is not closed, and if so, reporting that the low flow fault is restored;
and when the judgment result of the first judgment unit is yes, simultaneously triggering a third duration judgment unit.
17. The flow diagnostic system for a low pressure EGR system for a gasoline engine of claim 16 wherein said low flow diagnostic module further comprises:
the low flow rate repair counting unit is used for calculating the times of the low flow rate repair judging unit reporting that the low flow rate fault is repaired;
the low-flow restoration judging unit is used for judging whether the count value of the low-flow restoration counting unit is greater than or equal to a low-flow restoration threshold value or not, and if so, triggering the low-flow restoration prompting unit;
and the low flow recovery prompting unit is used for reporting low flow fault recovery.
18. The flow diagnostic system of a gasoline engine low pressure EGR system of claim 13, wherein the high flow diagnostic module comprises:
the third judging unit is used for judging whether the EGR valve is not opened or not, and if so, the fourth judging unit is triggered;
the fourth judging unit is used for judging whether the engine is successfully started and the EGR temperature is less than the diagnosis threshold value, and if so, the fifth judging unit is triggered;
the fifth judging unit is used for judging whether the current working condition meets the set working condition requirement or not, and if so, the sixth judging unit is triggered;
the mixing valve opening judging unit is used for judging whether the opening of the mixing valve is smaller than or equal to a calibrated opening threshold value or not, and if so, triggering the first processing unit;
a first processing unit which sets a first flag bit indicating that the operation of the mixing valve meets the high-flow diagnosis requirement, records the temperature of the EGR valve when the first flag bit is at a rising edge, and times a fourth time parameter indicating that the operation of the mixing valve meets the high-flow diagnosis requirement;
the fourth time length judging unit is used for judging whether the fourth time parameter is greater than or equal to the third calibration time or not, and if so, triggering the second processing unit;
a second processing unit that calculates a temperature change amount of the EGR valve in a time period indicated by the fourth time parameter, and clears the fourth time parameter to zero;
and the temperature change judging unit is used for judging whether the temperature change is greater than or equal to a fault temperature threshold value or not, and if so, reporting that a high-flow fault occurs.
19. The flow diagnostic system for a low pressure EGR system for a gasoline engine of claim 18 wherein said high flow diagnostic module further comprises:
the high-flow fault counting unit is used for calculating the frequency of the high-flow faults reported by the temperature change judging unit;
the high-flow fault judging unit is used for judging whether the counting value of the high-flow fault counting unit is greater than or equal to a high-flow fault threshold value or not, and if so, triggering the high-flow fault alarming unit;
and the high-flow fault alarm unit is used for reporting that the low-pressure EGR system has high-flow faults.
20. The flow diagnostic system for a low pressure EGR system for a gasoline engine of claim 18 wherein said high flow diagnostic module further comprises:
the high-flow restoration counting unit is used for adding 1 to the counting value of the high-flow restoration counting unit when the temperature change judging unit judges that the temperature change is smaller than the fault temperature threshold;
the high-flow restoration judging unit is used for judging whether the count value of the high-flow restoration counting unit is greater than or equal to a high-flow restoration threshold value or not, and if so, triggering the high-flow restoration prompting unit;
and the high-flow restoration prompting unit is used for reporting high-flow failure restoration.
21. The flow diagnostic system of a low pressure EGR system of a gasoline engine according to claim 18, characterized in that the temperature of the EGR valve recorded by the first processing unit is any one of an inlet temperature of the EGR valve, an outlet temperature of the EGR valve, an inlet-outlet temperature of the EGR valve, a temperature difference of the outlet temperature and the inlet temperature of the EGR valve.
22. A readable storage medium, characterized in that it has stored thereon at least one instruction or program, which is loaded by said processor and executes a method enabling the optimization method according to any one of claims 1 to 12.
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| CN113756999A (en) * | 2021-08-11 | 2021-12-07 | 联合汽车电子有限公司 | EGR flow fault detection method and device |
| CN115096596A (en) * | 2022-06-27 | 2022-09-23 | 中国第一汽车股份有限公司 | Method, device, equipment and medium for diagnosing low-pressure EGR (exhaust gas Recirculation) system of engine |
| CN115420505A (en) * | 2022-08-24 | 2022-12-02 | 东风汽车集团股份有限公司 | Test method and test device for exhaust gas recirculation system of engine |
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| CN109139307A (en) * | 2018-09-29 | 2019-01-04 | 汽解放汽车有限公司 | A kind of EGR valve flow diagnostic method |
| CN111120157A (en) * | 2020-03-31 | 2020-05-08 | 潍柴动力股份有限公司 | Detection method and device of EGR (exhaust gas Recirculation) system and ECU (electronic control Unit) |
| CN111736456A (en) * | 2020-06-24 | 2020-10-02 | 中国重汽集团济南动力有限公司 | Control and diagnosis mechanism of EGR (exhaust gas Recirculation) system, heavy-duty car and method |
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| CN113756999A (en) * | 2021-08-11 | 2021-12-07 | 联合汽车电子有限公司 | EGR flow fault detection method and device |
| CN115096596A (en) * | 2022-06-27 | 2022-09-23 | 中国第一汽车股份有限公司 | Method, device, equipment and medium for diagnosing low-pressure EGR (exhaust gas Recirculation) system of engine |
| CN115420505A (en) * | 2022-08-24 | 2022-12-02 | 东风汽车集团股份有限公司 | Test method and test device for exhaust gas recirculation system of engine |
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