CN118188197A - Fuel evaporation leakage diagnosis method for gasoline hybrid electric vehicle - Google Patents

Abstract

The invention relates to the technical field of control of automobile fuel equipment, in particular to a fuel evaporation leakage diagnosis method of a gasoline hybrid automobile. The invention adopts the configuration of the pressure of the high-pressure oil tank, the isolation valve and the low-pressure oil tank, and utilizes a diagnosis scheme combining power-on pre-judgment and active negative pressure pumping (DTESK) during cold start, namely, the diagnosis method which breaks the conventional configuration mode of the high-pressure oil tank and the DMTL. The invention has high diagnosis rate; the method is suitable for application scenes in a pure electric mode for long-term use; under the condition of saving oil and high or low temperature, the power-on can judge that no fault exists, and the working condition of starting the engine to idle speed is not needed to be operated; the method is suitable for being changed into PHEV by most traditional six-gasoline vehicles, and the software change amount is small, the calibration adaptability is good, and the trouble and the labor are saved; the temperature adaptability is wider than DMTL.

Description

Fuel evaporation leakage diagnosis method for gasoline hybrid electric vehicle

Technical Field

The invention relates to the technical field of control of automobile fuel equipment, in particular to a fuel evaporation leakage diagnosis method of a gasoline hybrid automobile.

Background

After release by light national Six Codes (GB 18352.6-2016), the importance of evaporative contaminant control is raised to a new level. To meet the requirements of type IV test (evaporative pollutant emission test) and 1mm evaporative leakage diagnostics, most gasoline plug-in hybrid/range-enhancing hybrid vehicles use a high pressure tank + isolation valve + DMTL module arrangement. In particular to a hybrid vehicle with longer pure electric driving mileage, the engine has less running opportunities and less negative pressure pumping opportunities, so a DMTL module for pumping air to an evaporation pipeline is configured, and the diagnosis rate is improved.

The evaporation leakage diagnosis configuration of the current gasoline plug-in hybrid/range-extended hybrid vehicle is mostly a high-pressure oil tank, an isolating valve and DMTL (Diagnostic Module Tank Leak) modules, wherein the DMTL modules are core components, are relatively expensive, have large arrangement requirements, and are relatively poor in precision, complexity and after-sales; in addition DMTL modules can only diagnose at 4-35 ℃ and cannot cover the ambient temperature of-7-4 ℃.

Disclosure of Invention

The patent provides an evaporation leakage diagnosis configuration and method without DMTL modules for a gasoline plug-in hybrid/range-extending hybrid vehicle, which is configured as a high-pressure oil tank and an isolation valve. The diagnosis method is to combine power-on pre-judgment and active negative pressure pumping. The DMTL modules are omitted, a large amount of cost is saved, the arrangement of other parts such as the carbon tank and the like can be more flexible, the after-sale fault rate can be reduced, and the after-sale cost of enterprises is reduced. The specific technical scheme is as follows:

A fuel evaporation leakage diagnosis method for a gasoline hybrid vehicle is provided, wherein an isolation valve is arranged on a pipeline for communicating a carbon tank with a high-pressure oil tank, and a low-pressure oil tank pressure sensor is arranged at one side close to the carbon tank, and the diagnosis method comprises the following steps:

S1, powering up a vehicle;

S2, the engine management system judges whether the cold start requirement is met, namely whether the engine stop time is more than 6 hours;

s3, if the shutdown time is less than or equal to 6 hours and the cold start condition is not met, not diagnosing;

S4, if the downtime is more than 6 hours, the cooling condition is met, and the pressure value of the pressure sensor of the high-pressure oil tank is read;

s5, judging whether the pressure of the high-pressure oil tank is in a suspected interval or not, and if the pressure is large or the vacuum degree is large, indicating that the oil tank has no leakage;

s6, if the pressure of the high-pressure oil tank is small at the moment, a fault is suspected, and an idle speed request is sent to the VCU;

S7, reading that the pressure is large or the vacuum degree is large in S5, indicating that the oil tank is free from leakage, and storing a fault-free result, wherein the fault-free result is not judged temporarily;

S8, reading that the vehicle is powered down in S13, and finally judging that the leakage diagnosis is fault-free in the later operation;

s9, after a suspected leakage is obtained, starting an engine and performing carbon tank desorption judgment when a vehicle is required to run;

s10, if not, the desorption stage is needed to be in a stage of waiting for the engine to start;

S11, after the engine is started and the carbon tank is detached, the VCU needs to judge whether the engine management system EMS has proper working condition to idle after obtaining the idle speed request (the negative pumping pressure operates under the idle working condition) sent by the engine management system EMS

S12, judging whether the idle speed working condition is met or not;

S13, judging whether the vehicle is powered down or not under the condition that the idle working condition is not met, if not, continuing to wait for judging whether the idle working condition is met, namely entering S12; if the vehicle is powered down and enters S8, the engine management system judges that no fault exists in the later running process;

S14, immediately entering into negative pressure pumping diagnosis when the idle working condition is met:

s15, judging whether the diagnosis process is finished;

s16, if the diagnosis is not finished, stopping, immediately returning to S11, and waiting for the next idle speed working condition to be met;

s17, obtaining a diagnosis result, namely a leakage gradient-compensation gradient, after diagnosis is completed;

S18, comparing the diagnosis result with a threshold value, and having no fault;

And S19, comparing the diagnosis result with a threshold value, and having faults.

Further, the negative pressure diagnosis in S14 includes the following steps:

S141: opening a carbon tank ventilation valve, closing a carbon tank electromagnetic valve, and checking whether the pressure of the low-pressure oil tank returns to the vicinity of the atmospheric pressure in a specified time; if not, judging that the carbon tank ventilation valve is in normal close fault;

S142: closing a carbon tank electromagnetic valve and a carbon tank ventilation valve to maintain the pressure of the oil tank, wherein the oil tank system is in a sealed state at the moment, and calculating the pressure rising gradient of the oil tank, namely the compensation gradient, which is not caused by leakage factors such as volatilization of natural oil gas; if the pressure of the oil tank at the stage is reduced to exceed a certain threshold value, judging that the electromagnetic normally open fault of the carbon tank exists;

S143: keeping the carbon tank ventilation valve normally closed, opening the carbon tank electromagnetic valve, and carrying out negative pressure pumping; if the situation of complete pumping is not achieved, judging that the electromagnetic valve of the carbon tank is in normal close fault; if the negative pressure can be further pumped to a certain degree, but the negative pressure pumping target is not achieved, judging that the coarse leakage fault exists; if the target negative pressure can be further pumped, the electromagnetic valve of the carbon tank is closed, the pressure is maintained, and the leakage gradient at the moment is calculated by using the pressure sensor of the low-pressure oil tank.

The invention adopts the configuration of the pressure of the high-pressure oil tank, the isolation valve and the low-pressure oil tank, and utilizes a diagnosis scheme combining power-on pre-judgment and active negative pressure pumping (DTESK) during cold start, namely, the diagnosis method which breaks the conventional configuration mode of the high-pressure oil tank and the DMTL.

The invention has the beneficial effects that: the DMTL pump is omitted, the cost is reduced, the quality after sale is reduced, and the diagnosis rate is high; the method is suitable for application scenes in a pure electric mode for long-term use; under the condition of saving oil and high or low temperature, the power-on can judge that no fault exists, and the working condition of starting the engine to idle speed is not needed to be operated; the method is suitable for being changed into PHEV by most traditional six-gasoline vehicles, and the software change amount is small, the calibration adaptability is good, and the trouble and the labor are saved; the temperature adaptability is wider than DMTL.

Drawings

FIG. 1 is a schematic diagram of the components of the method of the present invention;

FIG. 2 is a technical roadmap of the diagnostic flow of the method of the invention;

reference numerals:

(a) An intake manifold and a throttle valve; (b) a carbon canister solenoid valve; (c) a high pressure reservoir pressure sensor; (d) a high pressure tank; (e) a carbon canister; (f) a carbon canister vent valve; (g) an air cleaner; (h) a turbocharger; (i) a venturi and its piping; (k) a one-way valve; (l) an intake manifold pressure sensor; (m) a low pressure reservoir pressure sensor; (n) isolation valves.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

As shown in fig. 1, the method is characterized in that m is a low-pressure oil tank pressure sensor, and mainly has the functions of judging whether the oil tank and the pipeline have leakage or not when the pressure is pumped at idle speed and judging whether the desorption pipeline has falling or not when the desorption diagnosis is carried out. The specific diagnostic route is shown in fig. 2, and the steps are as follows:

S1, powering up a vehicle;

S2, the engine management system judges whether the cold start requirement is met, namely whether the engine stop time is more than 6 hours;

s3, if the shutdown time is less than or equal to 6 hours and the cold start condition is not met, not diagnosing;

S4, if the downtime is more than 6 hours, the cooling condition is met, and the pressure value of the pressure sensor of the high-pressure oil tank is read;

s5, judging whether the pressure of the high-pressure oil tank is in a suspected interval or not, and if the pressure is large or the vacuum degree is large, indicating that the oil tank has no leakage;

s6, if the pressure of the high-pressure oil tank is small at the moment, a fault is suspected, and an idle speed request is sent to the VCU;

S7, reading that the pressure is large or the vacuum degree is large in S5, indicating that the oil tank is free from leakage, and storing a fault-free result, wherein the fault-free result is not judged temporarily;

S8, reading that the vehicle is powered down in S13, and finally judging that the leakage diagnosis is fault-free in the later operation;

s9, after a suspected leakage is obtained, starting an engine and performing carbon tank desorption judgment when a vehicle is required to run;

s10, if not, the desorption stage is needed to be in a stage of waiting for the engine to start;

S11, after the engine is started and the carbon tank is detached, the VCU needs to judge whether the engine management system EMS has proper working condition to idle after obtaining the idle speed request (the negative pumping pressure operates under the idle working condition) sent by the engine management system EMS

S12, judging whether the idle speed working condition is met or not;

S13, judging whether the vehicle is powered down or not under the condition that the idle working condition is not met, if not, continuing to wait for judging whether the idle working condition is met, namely entering S12; if the vehicle is powered down and enters S8, the engine management system judges that no fault exists in the later running process;

S14, immediately entering into negative pressure pumping diagnosis when the idle working condition is met:

s15, judging whether the diagnosis process is finished;

s16, if the diagnosis is not finished, stopping, immediately returning to S11, and waiting for the next idle speed working condition to be met;

s17, obtaining a diagnosis result, namely a leakage gradient-compensation gradient, after diagnosis is completed;

S18, comparing the diagnosis result with a threshold value, and having no fault;

And S19, comparing the diagnosis result with a threshold value, and having faults.

Further, the negative pressure diagnosis in S14 includes the following steps:

S141: opening a carbon tank ventilation valve, closing a carbon tank electromagnetic valve, and checking whether the pressure of the low-pressure oil tank returns to the vicinity of the atmospheric pressure in a specified time; if not, judging that the carbon tank ventilation valve is in normal close fault;

S142: closing a carbon tank electromagnetic valve and a carbon tank ventilation valve to maintain the pressure of the oil tank, wherein the oil tank system is in a sealed state at the moment, and calculating the pressure rising gradient of the oil tank, namely the compensation gradient, which is not caused by leakage factors such as volatilization of natural oil gas; if the pressure of the oil tank at the stage is reduced to exceed a certain threshold value, judging that the electromagnetic normally open fault of the carbon tank exists;

S143: keeping the carbon tank ventilation valve normally closed, opening the carbon tank electromagnetic valve, and carrying out negative pressure pumping; if the situation of complete pumping is not achieved, judging that the electromagnetic valve of the carbon tank is in normal close fault; if the negative pressure can be further pumped to a certain degree, but the negative pressure pumping target is not achieved, judging that the coarse leakage fault exists; if the target negative pressure can be further pumped, the electromagnetic valve of the carbon tank is closed, the pressure is maintained, and the leakage gradient at the moment is calculated by using the pressure sensor of the low-pressure oil tank.

While the preferred embodiments of the present patent have been described in detail, the present patent is not limited to the above embodiments, and various changes may be made without departing from the spirit of the present patent within the knowledge of one of ordinary skill in the art.

Claims (2)

1. A fuel evaporation leakage diagnosis method for a gasoline hybrid vehicle is characterized by comprising the following steps of: an isolation valve is arranged on a pipeline for communicating the carbon tank with the high-pressure oil tank, and a low-pressure oil tank pressure sensor is arranged at one side close to the carbon tank, and the steps are as follows:

S1, powering up a vehicle;

S2, the engine management system judges whether the cold start requirement is met, namely whether the engine stop time is more than 6 hours;

s3, if the shutdown time is less than or equal to 6 hours and the cold start condition is not met, not diagnosing;

S4, if the downtime is more than 6 hours, the cooling condition is met, and the pressure value of the pressure sensor of the high-pressure oil tank is read;

s5, judging whether the pressure of the high-pressure oil tank is in a suspected interval or not, and if the pressure is large or the vacuum degree is large, indicating that the oil tank has no leakage;

s6, if the pressure of the high-pressure oil tank is small at the moment, a fault is suspected, and an idle speed request is sent to the VCU;

S7, reading that the pressure is large or the vacuum degree is large in S5, indicating that the oil tank is free from leakage, and storing a fault-free result, wherein the fault-free result is not judged temporarily;

S8, reading that the vehicle is powered down in S13, and finally judging that the leakage diagnosis is fault-free in the later operation;

s9, after a suspected leakage is obtained, starting an engine and performing carbon tank desorption judgment when a vehicle is required to run;

s10, if not, the desorption stage is needed to be in a stage of waiting for the engine to start;

S11, after the engine is started and the carbon tank is detached, the VCU needs to judge whether the engine management system EMS has proper working condition to idle after obtaining the idle speed request (the negative pumping pressure operates under the idle working condition) sent by the engine management system EMS

S12, judging whether the idle speed working condition is met or not;

S13, judging whether the vehicle is powered down or not under the condition that the idle working condition is not met, if not, continuing to wait for judging whether the idle working condition is met, namely entering S12; if the vehicle is powered down and enters S8, the engine management system judges that no fault exists in the later running process;

S14, immediately entering into negative pressure pumping diagnosis when the idle working condition is met:

s15, judging whether the diagnosis process is finished;

s16, if the diagnosis is not finished, stopping, immediately returning to S11, and waiting for the next idle speed working condition to be met;

s17, obtaining a diagnosis result, namely a leakage gradient-compensation gradient, after diagnosis is completed;

S18, comparing the diagnosis result with a threshold value, and having no fault;

And S19, comparing the diagnosis result with a threshold value, and having faults.

2. The method for diagnosing fuel evaporation leakage of a gasoline hybrid vehicle according to claim 1, characterized by: the negative pressure diagnosis in step S14 includes the steps of:

S141: opening a carbon tank ventilation valve, closing a carbon tank electromagnetic valve, and checking whether the pressure of the low-pressure oil tank returns to the vicinity of the atmospheric pressure in a specified time; if not, judging that the carbon tank ventilation valve is in normal close fault;

S142: closing a carbon tank electromagnetic valve and a carbon tank ventilation valve to maintain the pressure of the oil tank, wherein the oil tank system is in a sealed state at the moment, and calculating the pressure rising gradient of the oil tank, namely the compensation gradient, which is not caused by leakage factors such as volatilization of natural oil gas; if the pressure of the oil tank at the stage is reduced to exceed a certain threshold value, judging that the electromagnetic normally open fault of the carbon tank exists;

S143: keeping the carbon tank ventilation valve normally closed, opening the carbon tank electromagnetic valve, and carrying out negative pressure pumping; if the situation of complete pumping is not achieved, judging that the electromagnetic valve of the carbon tank is in normal close fault; if the negative pressure can be further pumped to a certain degree, but the negative pressure pumping target is not achieved, judging that the coarse leakage fault exists; if the target negative pressure can be further pumped, the electromagnetic valve of the carbon tank is closed, the pressure is maintained, and the leakage gradient at the moment is calculated by using the pressure sensor of the low-pressure oil tank.