CN111075610A - Carbon tank desorption pipeline flow diagnosis method and system - Google Patents
Carbon tank desorption pipeline flow diagnosis method and system Download PDFInfo
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- CN111075610A CN111075610A CN201911264754.7A CN201911264754A CN111075610A CN 111075610 A CN111075610 A CN 111075610A CN 201911264754 A CN201911264754 A CN 201911264754A CN 111075610 A CN111075610 A CN 111075610A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M25/00—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
- F02M25/08—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding fuel vapours drawn from engine fuel reservoir
- F02M25/0809—Judging failure of purge control system
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D41/003—Adding fuel vapours, e.g. drawn from engine fuel reservoir
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/22—Safety or indicating devices for abnormal conditions
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/22—Safety or indicating devices for abnormal conditions
- F02D2041/224—Diagnosis of the fuel system
- F02D2041/225—Leakage detection
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
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Abstract
The invention discloses a carbon tank desorption pipeline flow diagnosis method and a system, wherein the method comprises the following steps: when the flow diagnosis activation condition of the carbon tank desorption pipeline is met, acquiring the control frequency of the carbon tank control valve and an initial flow frequency signal value in the carbon tank desorption pipeline; acquiring a flow frequency signal value with the same frequency as the control frequency of the carbon tank control valve according to the initial flow frequency signal value in the carbon tank desorption pipeline; calculating the amplitude of the flow signal in the desorption pipeline of the carbon tank according to the flow frequency signal value; judging whether the flow signal amplitude exceeds a preset threshold value or not according to the flow signal amplitude; if so, judging that the carbon tank desorption pipeline is normal, otherwise, judging that the carbon tank desorption pipeline has a fault.
Description
Technical Field
The invention relates to the field of automobile fuel control, in particular to a carbon tank desorption pipeline flow diagnosis method and system.
Background
The environment is the basis for human survival, and the use amount of automobiles is increased, so that great convenience is provided for people, but the environment is polluted, and the emission of automobile exhaust becomes an important pollution source of the atmospheric environment. Therefore, since China has pursued emission regulations, the emission regulations at each stage are much more stringent than those at the previous stage. The method comprises the following steps of based on the latest emission regulation, making a mandatory requirement on the monitoring of the desorption flow of the carbon tank: a fault is declared when no desorption flow into the engine can be detected and the IUPR minimum diagnostic rate requirement is placed on the diagnosis.
For the diagnosis of the desorption flow of the carbon tank, in the prior art, a pipeline pressure sensor is installed on a high-pressure desorption pipeline, and the desorption flow in the pipeline is judged according to the pressure change of the pipeline pressure sensor.
Disclosure of Invention
In view of the above problems in the prior art, an object of the present invention is to provide a method and a system for diagnosing a flow rate of a canister desorption pipeline, which can solve the problems in the prior art that a sensor is required to be added for flow rate monitoring, so that the cost is increased, and the like.
In order to solve the technical problems, the specific technical scheme of the invention is as follows:
in one aspect, the present invention provides a carbon tank desorption pipeline flow diagnosis method, which is applied to a carbon tank desorption pipeline system at least comprising a carbon tank control valve and an evaporation leakage monitoring device, wherein the evaporation leakage monitoring device comprises a pressure sensor, and the method comprises the following steps:
when the flow diagnosis activation condition of the carbon tank desorption pipeline is met, acquiring the control frequency of the carbon tank control valve and an initial flow frequency signal value in the carbon tank desorption pipeline;
acquiring a flow frequency signal value with the same frequency as the control frequency of the carbon tank control valve according to the initial flow frequency signal value in the carbon tank desorption pipeline;
calculating the amplitude of the flow signal in the desorption pipeline of the carbon tank according to the flow frequency signal value;
judging whether the flow signal amplitude exceeds a preset threshold value or not according to the flow signal amplitude;
when the flow signal amplitude exceeds a preset threshold value, the carbon tank desorption pipeline is judged to be normal, and when the flow signal amplitude does not exceed the preset threshold value, the carbon tank desorption pipeline is judged to be in fault.
Further, the carbon tank desorption pipeline comprises a high-pressure desorption pipeline and a low-pressure desorption pipeline, wherein,
the initial flow frequency signal value in the carbon tank desorption pipeline is obtained as follows:
acquiring a frequency signal value in a pressure sensor to acquire an initial flow frequency signal value in the high-pipe desorption pipeline, or,
and acquiring a flow signal value in an air inlet manifold to acquire an initial flow frequency signal value in the low-pressure desorption pipeline.
Further, the obtaining a flow frequency signal value having the same frequency as the control frequency of the canister control valve according to the initial flow frequency signal value in the canister desorption pipeline includes:
and obtaining a flow frequency signal value with the same frequency as the control frequency of the carbon tank control valve through low-pass filtering processing and high-pass filtering processing.
Further, the calculating the flow signal amplitude in the desorption pipeline of the carbon tank according to the flow frequency signal value comprises:
and calculating the flow signal amplitude in the carbon tank desorption pipeline in the preset time through Fourier transform according to the flow frequency signal value.
Further, the when-canister desorption pipeline flow diagnosis activation condition comprises:
obtaining vehicle working condition information, wherein the working condition information at least comprises the following parameters: canister control valve duty cycle, vehicle system voltage, engine speed, ambient temperature, canister control valve frequency, intake manifold pressure, ambient pressure, engine speed, canister control valve duty cycle, and fuel cut-off status;
and when each parameter in the working condition information reaches a preset condition, reaching the carbon tank desorption pipeline flow diagnosis activation condition.
In another aspect, the present invention further provides a carbon canister desorption pipeline flow diagnosis system, configured to execute the above carbon canister desorption pipeline flow diagnosis method, where the system includes a carbon canister control valve and an evaporation leakage monitoring device, the evaporation leakage monitoring device includes a pressure sensor, and the system further includes:
the first judgment module is used for judging whether the carbon tank desorption pipeline flow diagnosis activation condition is met;
the first acquisition module is used for acquiring the control frequency of the carbon tank control valve and an initial flow frequency signal value in the carbon tank desorption pipeline when the flow diagnosis activation condition of the carbon tank desorption pipeline is reached;
the second acquisition module is used for acquiring a flow frequency signal value with the same frequency as the control frequency of the carbon tank control valve according to the initial flow frequency signal value in the carbon tank desorption pipeline;
the calculation module is used for calculating the flow signal amplitude in the carbon tank desorption pipeline according to the flow frequency signal value;
the second judgment module is used for judging whether the flow signal amplitude exceeds a preset threshold value or not according to the flow signal amplitude;
and the diagnosis module is used for judging that the carbon tank desorption pipeline is normal when the flow signal amplitude exceeds a preset threshold value, and judging that the carbon tank desorption pipeline has a fault when the flow signal amplitude does not exceed the preset threshold value.
Further, the first obtaining module comprises:
the first acquisition unit is used for acquiring the control frequency of the carbon tank control valve when the carbon tank desorption pipeline flow diagnosis activation condition is reached;
the second acquisition unit is used for acquiring a frequency signal value in the pressure sensor to acquire an initial flow frequency signal value in the high-pipe desorption pipeline when the flow diagnosis activation condition of the carbon tank desorption pipeline is reached;
and the third acquisition unit is used for acquiring a flow signal value in the air intake manifold to acquire an initial flow frequency signal value in the low-pressure desorption pipeline when the carbon tank desorption pipeline flow diagnosis activation condition is reached.
Further, the second obtaining module includes:
and the fourth acquisition unit is used for acquiring a flow frequency signal value with the same frequency as the control frequency of the carbon tank control valve through low-pass filtering processing and high-pass filtering processing.
Further, the calculation module includes:
and the calculating unit is used for calculating the flow signal amplitude in the carbon tank desorption pipeline in the preset time through Fourier transform according to the flow frequency signal value.
Further, the first determining module includes:
a fifth obtaining unit, configured to obtain vehicle operating condition information, where the operating condition information at least includes the following parameters: canister control valve duty cycle, vehicle system voltage, engine speed, ambient temperature, canister control valve frequency, intake manifold pressure, ambient pressure, engine speed, canister control valve duty cycle, and fuel cut-off status;
and the first judgment unit is used for judging whether each parameter in the working condition information reaches a preset condition or not, and if so, reaching the carbon tank desorption pipeline flow diagnosis activation condition.
By adopting the technical scheme, the carbon tank desorption pipeline flow diagnosis method and system have the following beneficial effects:
1. according to the carbon tank desorption pipeline flow diagnosis method and system, diagnosis of desorption flow of the double-way carbon tank is completed based on the existing sensors and actuators, a pipeline pressure sensor does not need to be additionally installed on the desorption pipeline, and cost and space of the whole vehicle are saved.
2. The carbon tank desorption pipeline flow diagnosis method and system can meet the requirements of national emission regulations on carbon tank diagnosis flow, can effectively improve the quality of diagnosis signals, and can reduce the misjudgment rate.
3. According to the carbon tank desorption pipeline flow diagnosis method and system, software development cost caused by introduction of a new pipeline sensor is reduced, the system structure is simplified, and the requirement for light weight of a vehicle is met.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings used in the description of the embodiment 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 invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
FIG. 1 is a schematic diagram of a carbon canister desorption line according to the present invention;
FIG. 2 is a step diagram of a carbon tank desorption pipeline flow diagnosis method according to the present invention;
FIG. 3 is a block diagram of a flow monitoring module of a two-way canister desorption pipeline in an embodiment of the invention;
FIG. 4 is a flow chart of a method for diagnosing flow of a canister desorption line in accordance with an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a carbon tank desorption pipeline flow diagnosis system according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or device.
Example 1
With the release of the national emission standard, the requirement on the exhaust emission of a vehicle is higher and higher, the latest emission regulations impose the mandatory requirement on the monitoring of the desorption flow of the carbon tank, but for the diagnosis of the desorption flow of the carbon tank, the pipeline pressure sensor is arranged on the high-pressure desorption pipeline in the prior art, so that the cost of the whole vehicle is increased due to the fact that the sensor is additionally arranged, and the cost and the period of software development are increased due to the fact that the sensor which is also increased accordingly needs to be designed and diagnosed.
As shown in fig. 1, a pipeline diagram of a carbon tank pipeline is generally adopted, and a two-way desorption pipeline system is adopted. When the engine is in a static state, fuel oil in the fuel tank volatilizes, steam of the fuel oil volatilizes into the fuel oil volatilizing cavity in the carbon tank through the pipeline and is adsorbed, condensed and reduced into the fuel oil by the activated carbon, and redundant gas is discharged through the breathing port of the carbon tank. When the engine runs, the engine enters a steady-state working condition, the carbon tank electromagnetic valve is electrified and then the pipeline is conducted, external fresh air is supplemented into the carbon tank from the carbon tank breathing port, flows through the absorption layer in the carbon tank and is mixed with fuel oil to form combustible gas which flows into an engine air inlet pipe, and at the moment, the activated carbon in the carbon tank is gradually reduced due to the suction effect of the engine. The desorption flow flowing through the carbon tank electromagnetic valve has two paths of choices, one path is flowing into the front end of the supercharger through the throttle valve and the high-pressure desorption pipeline, is mixed with fresh air entering through the air filter, then flows into the cylinder through the supercharger, the intercooling throttle valve and the air inlet manifold to participate in combustion, and is discharged through the exhaust manifold after the combustion is finished; and the other path flows into the front end of the throttle valve through the throttle valve and a low-pressure desorption pipeline, is mixed with the main gas path, flows into the cylinder through the air inlet manifold to participate in combustion, and is discharged through the exhaust pipe after combustion. The choice of two desorption lines depends mainly on the pressure difference between the pressure of the intake manifold and the ambient pressure. When the pressure of the manifold is smaller than the environmental pressure, the engine is in a non-supercharging state, the desorption flow of the carbon tank is selected as a low-pressure desorption pipeline, namely two paths, and the flushing power comes from the pressure difference between the front and the rear of the throttle valve; when the manifold pressure is greater than the ambient pressure, the engine is in a pressurized state, and the carbon tank flushing pipeline selects a high-pressure desorption pipeline, namely one pipeline, and mainly utilizes the vacuum in front of the compressor. For the high-pressure desorption pipeline, the desorption flow of the high-pressure desorption pipeline is also very small due to the fact that the vacuum degree of the front end of the air compressor is small. In order to increase the flow of the pipeline, a venturi tube is added in the pipeline, the B end of the venturi tube takes the supercharged gas after cold cooling, the A end of the venturi tube is connected with the flow of the high-pressure desorption carbon tank, the C end of the venturi tube is connected with the front end of the supercharger, due to the characteristics of the venturi tube, the desorption flow velocity of the B end is low, the desorption flow velocity of the C end is high, the high-pressure desorption flow output by the A end can be adsorbed at low pressure, and therefore the desorption flow is accelerated to enter the front end of the supercharger.
Due to the release of the national six-emission standard, an Evaporative leakage monitoring device (ELCM for short) must be installed on a vehicle meeting the national six-emission standard, the Evaporative leakage monitoring device can meet the requirements of national six regulations on fuel Evaporative leakage diagnosis, and an Evaporative leakage monitoring Module (ELCM) mainly comprises a vacuum pump, a motor, an electromagnetic reversing valve, a pressure sensor and a throttling hole. When the ELCM electromagnetic directional valve is not electrified (normal state), the atmosphere is communicated with a carbon tank breathing port, the pressure sensor in the ELCM can be used for measuring the pressure of a pipeline, the used carbon tank control valve is a switch valve, the frequency f is controlled, the desorption flow of the carbon tank flows into an air inlet manifold, and the signal of the frequency f acts on the pressure signal of the air inlet manifold.
An embodiment of the present specification provides a carbon canister desorption pipeline flow diagnosis method based on the above principle, which is applied to a carbon canister desorption pipeline system at least comprising a carbon canister control valve and an evaporation leakage monitoring device, wherein the evaporation leakage monitoring device comprises a pressure sensor, as shown in fig. 2, and the method comprises the following steps:
s1: when the flow diagnosis activation condition of the carbon tank desorption pipeline is met, acquiring the control frequency of the carbon tank control valve and an initial flow frequency signal value in the carbon tank desorption pipeline;
the activation of the carbon tank desorption pipeline is determined by the working condition information of the vehicle, and specifically, at least the following parameters are included: canister control valve duty cycle, vehicle system voltage, engine speed, ambient temperature, canister control valve frequency, intake manifold pressure, ambient pressure, engine speed, canister control valve duty cycle, and fuel cut-off status; when each parameter in the working condition information reaches a preset condition, the flow diagnosis activation condition of the carbon tank desorption pipeline is reached;
in some embodiments, due to the design of the two-way canister line, the activation condition may include an initial condition and a basic condition, wherein the initial condition is to determine whether the canister system reaches an operating state, and the basic condition is to determine whether to select a high-pressure canister line diagnostic or a low-pressure canister line diagnostic, and specifically, the initial condition is related to a canister control valve duty cycle, a system voltage, an engine speed, an ambient temperature, and a canister control valve frequency, and the basic condition is related to an intake manifold pressure, an ambient pressure, an engine speed, a canister control valve duty cycle, and an oil cut flag. The preset parameters selected according to different vehicle types and working condition information are different.
When the activation condition is met, the carbon tank control valve is used as a switch valve, the control frequency of the carbon tank control valve is determined according to the frequency of the switch of the carbon tank control valve, whether the diagnosis of the high-pressure desorption pipeline or the diagnosis of the low-pressure desorption pipeline is determined according to the activation condition met, and when the diagnosis of the high-pressure desorption pipeline is performed, a frequency signal in a pressure sensor in the ELCM is required to be acquired to serve as an initial flow frequency signal value in the high-pipe desorption pipeline; when diagnosing the low-pressure desorption pipeline, acquiring a flow signal value in the intake manifold as an initial flow frequency signal value in the low-pressure desorption pipeline.
S2: acquiring a flow frequency signal value with the same frequency as the control frequency of the carbon tank control valve according to the initial flow frequency signal value in the carbon tank desorption pipeline;
the initial flow frequency signal value is filtered to remove other signals, and the initial flow frequency signal value can be filtered to obtain a flow frequency signal value with the same frequency as the carbon canister control valve control frequency, and specifically, high-pass filtering and low-pass filtering can be performed through a filter.
S3: calculating the amplitude of the flow signal in the desorption pipeline of the carbon tank according to the flow frequency signal value;
in this embodiment, it can be obtained by the fourier transform principle, and the fourier transform expression can express the time domain function satisfying a certain condition as a trigonometric function (sine or cosine function) or a linear combination of their integrals. The flow frequency signal values can thus be converted into visualized flow signal amplitudes by means of fourier transformation. The specific principle comprises the following steps:
the Fourier amplitude Xk is recorded, the frequency is k, the discrete Fourier transform interval length is N, the imaginary number unit is i, the number of sampling points is N, and the transform formula can be described as follows:
based on Euler formula transformation:
i.e., the discrete fourier transform can be described as:
the real part Rex [ n ] and imaginary part Imx [ n ] in equation (3) can be described as:
on the basis of obtaining Rex [ n ] and imaginary Imx [ n ], the flow signal amplitude over a predetermined time may be obtained.
S4: judging whether the flow signal amplitude exceeds a preset threshold value or not according to the flow signal amplitude;
in order to better display the true value of the flow signal amplitude, the average value of the flow signal amplitude in a preset sampling period can be obtained as a reference and compared with a preset threshold value, wherein the preset threshold values of the high-pressure desorption pipeline diagnosis and the low-pressure desorption pipeline diagnosis are different and are determined according to different working condition information.
S5: when the flow signal amplitude exceeds a preset threshold value, the carbon tank desorption pipeline is judged to be normal, and when the flow signal amplitude does not exceed the preset threshold value, the carbon tank desorption pipeline is judged to be in fault.
On the basis of the above method for diagnosing desorption management flow of the carbon tank, an embodiment of the present specification further provides a system for diagnosing desorption management flow of the carbon tank, where the system includes a carbon tank control valve and an evaporation leakage monitoring device, the evaporation leakage monitoring device includes a pressure sensor, and as shown in fig. 5, the system further includes:
the first judgment module is used for judging whether the carbon tank desorption pipeline flow diagnosis activation condition is met;
the first acquisition module is used for acquiring the control frequency of the carbon tank control valve and an initial flow frequency signal value in the carbon tank desorption pipeline when the flow diagnosis activation condition of the carbon tank desorption pipeline is reached;
the second acquisition module is used for acquiring a flow frequency signal value with the same frequency as the control frequency of the carbon tank control valve according to the initial flow frequency signal value in the carbon tank desorption pipeline;
the calculation module is used for calculating the flow signal amplitude in the carbon tank desorption pipeline according to the flow frequency signal value;
the second judgment module is used for judging whether the flow signal amplitude exceeds a preset threshold value or not according to the flow signal amplitude;
and the diagnosis module is used for judging that the carbon tank desorption pipeline is normal when the flow signal amplitude exceeds a preset threshold value, and judging that the carbon tank desorption pipeline has a fault when the flow signal amplitude does not exceed the preset threshold value.
In some embodiments, the first obtaining module comprises:
the first acquisition unit is used for acquiring the control frequency of the carbon tank control valve when the carbon tank desorption pipeline flow diagnosis activation condition is reached;
the second acquisition unit is used for acquiring a frequency signal value in the pressure sensor to acquire an initial flow frequency signal value in the high-pipe desorption pipeline when the flow diagnosis activation condition of the carbon tank desorption pipeline is reached;
and the third acquisition unit is used for acquiring a flow signal value in the air intake manifold to acquire an initial flow frequency signal value in the low-pressure desorption pipeline when the carbon tank desorption pipeline flow diagnosis activation condition is reached.
In some embodiments, the second obtaining module comprises:
and the fourth acquisition unit is used for acquiring a flow frequency signal value with the same frequency as the control frequency of the carbon tank control valve through low-pass filtering processing and high-pass filtering processing.
In some embodiments, the calculation module comprises:
and the calculating unit is used for calculating the flow signal amplitude in the carbon tank desorption pipeline in the preset time through Fourier transform according to the flow frequency signal value.
In some embodiments, the first determining module comprises:
a fifth obtaining unit, configured to obtain vehicle operating condition information, where the operating condition information at least includes the following parameters: canister control valve duty cycle, vehicle system voltage, engine speed, ambient temperature, canister control valve frequency, intake manifold pressure, ambient pressure, engine speed, canister control valve duty cycle, and fuel cut-off status;
and the first judgment unit is used for judging whether each parameter in the working condition information reaches a preset condition or not, and if so, reaching the carbon tank desorption pipeline flow diagnosis activation condition.
As used herein, "module" and "unit" include, but are not limited to, a non-transitory computer-readable medium storing instructions, instructions for execution on a machine, hardware, firmware, software for execution on a machine, and/or a combination of each for performing function(s) or action(s), and/or causing a function or action from another module or unit, a method, and/or a system. A module or unit may also comprise logic, a software controlled microprocessor, discrete logic circuits, analog circuits, digital circuits, programmed logic devices, memory devices containing instructions for execution, logic gates, combinations of gates, and/or other circuit components. Multiple modules or units may be combined into one module or unit, and a single module or unit may be distributed among multiple modules or units.
Exemplarily, as shown in fig. 3 to 4, a specific example of the method described in this specification is:
evaporative leak monitoring modules (ELCMs) are primarily used for line leak diagnostics. When the ELCM electromagnetic directional valve is not electrified (normal state), the atmosphere is communicated with the breathing port of the carbon tank, and the pressure sensor in the carbon tank can be used for measuring the pressure of the pipeline. The used carbon tank control valve is a switch valve, the control frequency f is 10HZ, the desorption flow of the carbon tank flows into the air inlet manifold, a signal equivalent to 10HZ acts on a pressure signal of the air inlet manifold, and for a low-pressure desorption pipeline, the signal f in the pressure of the air inlet manifold is 10HZ separated through Fourier transform, so that the low-pressure desorption flow in the management can be effectively monitored; for the high-pressure desorption pipeline, the pressure signal of f being 10HZ in the ELCM pressure sensor is separated through Fourier transformation, and the high-pressure desorption flow in the management can be effectively monitored.
Firstly, judging activation conditions including initial condition judgment and basic condition judgment
Step 1: initial condition judgment, which is related to the duty ratio of the carbon tank control valve, system voltage, engine speed, environment temperature and carbon tank control valve frequency;
preferred embodiment initial conditions:
A. the carbon canister control valve duty cycle is > 0;
B. the system voltage is controlled to be 10V-16V;
C. engine speed >500 rpm;
D. ambient temperature > -10 degC;
E. the control frequency is 10HZ, and no obvious fluctuation exists;
step 2: basic condition judgment, wherein the triggering conditions of the high-pressure or low-pressure desorption pipeline are related to the pressure of an air inlet manifold, the ambient pressure, the rotating speed of an engine, the duty ratio of a carbon tank control valve and the fuel cut-off state;
the triggering conditions of the low-pressure desorption pipeline of the preferred embodiment are as follows:
a.15kpa < intake manifold pressure < ambient pressure (101 KPa under standard conditions);
B. engine speed <3000 rpm;
c.75% > carbon canister control valve duty cycle > 25%;
D. the engine has no fuel cut;
the triggering conditions of the high-pressure desorption pipeline in the preferred embodiment are as follows:
A. intake manifold pressure > ambient pressure (101 KPa under standard conditions);
B. engine speed <6000 rpm;
c.75% > carbon canister control valve duty cycle > 25%;
D. the engine has no fuel cut;
and step 3: and (3) carrying out filtering treatment:
aiming at a high-pressure desorption pipeline: performing ELCM pressure low-pass filtering processing, namely removing a high-frequency signal with the frequency f being more than 10HZ in a pressure sensor signal in the ELCM by adopting a low-pass filter; ELCM pressure high-pass filtering processing, namely removing low-frequency signals with frequency f less than 10HZ in pressure sensor signals in the ELCM by adopting a high-pass filter;
aiming at a low-pressure desorption pipeline: performing low-pass filtering processing on the pressure of the intake manifold, and removing a high-frequency signal with the frequency f being more than 10HZ in the pressure signal of the intake manifold by using a low-pass filter; performing high-pass filtering processing on the pressure of the intake manifold, and removing a low-frequency signal with the frequency f being less than 10HZ in the pressure signal of the intake manifold by using a high-pass filter;
it should be noted that, in some other embodiments, step 3 may be placed before step 1 and step 2, which is also within the scope of the present disclosure.
And 4, step 4: fourier transform estimation of desorption pipeline amplitude: the time domain signal of the carbon tank desorption pipeline can be converted into a frequency signal for processing through Fourier transform, and the amplitude and phase change of the signal can be accurately estimated. The quality of a diagnostic signal is improved, and the Fourier transform representation of the misjudgment rate is reduced, so that a time domain function meeting a certain condition can be represented as a trigonometric function (sine or cosine function) or a linear combination of integral of the trigonometric function and the cosine function. The Fourier amplitude Xk is recorded, the frequency is k, the discrete Fourier transform interval length is N, the imaginary number unit is i, the number of sampling points is N, and the transform formula can be described as follows:
based on Euler formula transformation:
i.e., the discrete fourier transform can be described as:
the real part Rex [ n ] and imaginary part Imx [ n ] in equation (3) can be described as:
the fourier transform is used to calculate the signal amplitude within the predetermined time, and based on equation (4), the specific implementation for the high-pressure or low-pressure desorption pipeline can be described as:
1) fourier transform counting, with a given sampling period ts1 ═ 10ms, and an nth 0(n0>0) sampling period, the count of the sine function CntSin1[ n0] can be described as:
CntSin1[n0]＝CntSin1[n0-1]+10 (5)
in conjunction with equation (5), the sampling frequency f of the canister control valve is 10kHZ, and the n-th n0(n0>0) counts CntCos1[ n0] of the cosine function of the sampling period can be described as:
2) a sinusoidal signal is generated. When the intake manifold pressure P1 ═ P10 is less than ambient pressure, and the nth ═ n0(n0>1) sampling periods, the real part Rex1[ n0] and imaginary part Imx1[ n0] of the high-or low-pressure desorption circuit discrete fourier transform can be described as:
bringing (6) into (7), the formula (7) can in turn be described as:
3) and Fourier transform integration, which mainly calculates the integral value of a real part and an imaginary part of the Fourier transform in a period of time. Setting the integration duration to be H1 ═ 0.6S, and based on the sampling period ts1 ═ 10ms, the number of times of integration is NT1 ═ H1/ts1 ═ 60 times, and the nth ═ n0(NT1> n0>0) sampling periods, the integrated real part IntegRex1 and imaginary part IntegImx1 for the high-pressure or low-pressure desorption pipeline discrete fourier transform can be described as:
4) the calculation of the amplitude of the flow of the carbon tank of the high-pressure desorption pipeline or the low-pressure desorption pipeline is based on the values of an integrated real part IntegRex1 and an imaginary part IntegImx1 of the discrete Fourier transform of the low-pressure desorption pipeline, and the amplitude Amp1 of the intake manifold pressure signal can be described as follows in the NT 1-60 times:
and 5: the mean signal amplitude is compared to a threshold. The cumulative MT1 is the sum of the fourier signal amplitudes of the high-pressure or low-pressure desorption lines 10 times, then the fourier-mean signal amplitude MeanAmp1 can be described as:
and (6) diagnosis and judgment. When the mean signal amplitude value MeanAmp1 is greater than the set threshold value P1limit of 0.1kPa, indicating that the high-pressure or low-pressure desorption pipeline has flow and the pipeline does not fall off, and determining that the pipeline is normal; and when the mean value signal amplitude MeanAmp1 is smaller than the set threshold P1limit which is 0.1kPa, indicating that no flow exists in the high-pressure or low-pressure desorption pipeline, and determining as a fault.
On the basis of the method and the system for diagnosing the flow rate of the carbon tank desorption pipeline, an embodiment of the specification further provides a vehicle which is provided with the method and diagnoses the flow rate of the carbon tank desorption pipeline through the diagnosis method.
The carbon tank desorption pipeline flow diagnosis method and the carbon tank desorption pipeline flow diagnosis system have the following beneficial effects that:
1) according to the carbon tank desorption pipeline flow diagnosis method and system, the diagnosis of the desorption flow of the double-channel carbon tank is completed based on the existing sensors and actuators, the pipeline pressure sensor does not need to be additionally arranged on the desorption pipeline, and the cost and the space of the whole vehicle are saved.
2) The carbon tank desorption pipeline flow diagnosis method and system can meet the requirements of national emission regulations on carbon tank diagnosis flow, can effectively improve the quality of diagnosis signals, and can reduce the misjudgment rate.
3) According to the carbon tank desorption pipeline flow diagnosis method and system, software development cost caused by introduction of a new pipeline sensor is reduced, the system structure is simplified, and the requirement for light weight of a vehicle is met.
While the invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the invention can be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (10)
1. A carbon tank desorption pipeline flow diagnosis method is applied to a carbon tank desorption pipeline system at least comprising a carbon tank control valve and an evaporation leakage monitoring device, wherein the evaporation leakage monitoring device comprises a pressure sensor, and the method is characterized by comprising the following steps:
when the flow diagnosis activation condition of the carbon tank desorption pipeline is met, acquiring the control frequency of the carbon tank control valve and an initial flow frequency signal value in the carbon tank desorption pipeline;
acquiring a flow frequency signal value with the same frequency as the control frequency of the carbon tank control valve according to the initial flow frequency signal value in the carbon tank desorption pipeline;
calculating the amplitude of the flow signal in the desorption pipeline of the carbon tank according to the flow frequency signal value;
judging whether the flow signal amplitude exceeds a preset threshold value or not according to the flow signal amplitude;
when the flow signal amplitude exceeds a preset threshold value, the carbon tank desorption pipeline is judged to be normal, and when the flow signal amplitude does not exceed the preset threshold value, the carbon tank desorption pipeline is judged to be in fault.
2. The carbon tank desorption line flow diagnostic method of claim 1, wherein the carbon tank desorption line comprises a high pressure desorption line and a low pressure desorption line, wherein,
the initial flow frequency signal value in the carbon tank desorption pipeline is obtained as follows:
acquiring a frequency signal value in a pressure sensor to acquire an initial flow frequency signal value in the high-pressure desorption pipeline, or,
and acquiring a flow signal value in an air inlet manifold to acquire an initial flow frequency signal value in the low-pressure desorption pipeline.
3. The carbon tank desorption pipeline flow diagnosis method as claimed in claim 1, wherein the obtaining of the flow frequency signal value having the same frequency as the carbon tank control valve control frequency according to the initial flow frequency signal value in the carbon tank desorption pipeline comprises:
and obtaining a flow frequency signal value with the same frequency as the control frequency of the carbon tank control valve through low-pass filtering processing and high-pass filtering processing.
4. The method for diagnosing the flow rate of the desorption pipeline of the carbon tank as claimed in claim 1, wherein the calculating the flow signal amplitude value in the desorption pipeline of the carbon tank according to the flow frequency signal value comprises:
and calculating the flow signal amplitude in the carbon tank desorption pipeline in the preset time through Fourier transform according to the flow frequency signal value.
5. The method for diagnosing the flow rate of the desorption pipeline of the carbon tank as claimed in claim 1, wherein the when the activated condition for diagnosing the flow rate of the desorption pipeline of the carbon tank is reached comprises:
obtaining vehicle working condition information, wherein the working condition information at least comprises the following parameters: canister control valve duty cycle, vehicle system voltage, engine speed, ambient temperature, canister control valve frequency, intake manifold pressure, ambient pressure, engine speed, canister control valve duty cycle, and fuel cut-off status;
and when each parameter in the working condition information reaches a preset condition, reaching the carbon tank desorption pipeline flow diagnosis activation condition.
6. A carbon canister desorption pipeline flow diagnostic system for performing the carbon canister desorption pipeline flow diagnostic method of any one of claims 1 to 5, the system comprising a carbon canister control valve and an evaporative leakage monitoring device, the evaporative leakage monitoring device comprising a pressure sensor, the system further comprising:
the first judgment module is used for judging whether the carbon tank desorption pipeline flow diagnosis activation condition is met;
the first acquisition module is used for acquiring the control frequency of the carbon tank control valve and an initial flow frequency signal value in the carbon tank desorption pipeline when the flow diagnosis activation condition of the carbon tank desorption pipeline is reached;
the second acquisition module is used for acquiring a flow frequency signal value with the same frequency as the control frequency of the carbon tank control valve according to the initial flow frequency signal value in the carbon tank desorption pipeline;
the calculation module is used for calculating the flow signal amplitude in the carbon tank desorption pipeline according to the flow frequency signal value;
the second judgment module is used for judging whether the flow signal amplitude exceeds a preset threshold value or not according to the flow signal amplitude;
and the diagnosis module is used for judging that the carbon tank desorption pipeline is normal when the flow signal amplitude exceeds a preset threshold value, and judging that the carbon tank desorption pipeline has a fault when the flow signal amplitude does not exceed the preset threshold value.
7. The carbon tank desorption line flow diagnostic system of claim 6, wherein the first acquisition module comprises:
the first acquisition unit is used for acquiring the control frequency of the carbon tank control valve when the carbon tank desorption pipeline flow diagnosis activation condition is reached;
the second acquisition unit is used for acquiring a frequency signal value in the pressure sensor to acquire an initial flow frequency signal value in the high-pipe desorption pipeline when the flow diagnosis activation condition of the carbon tank desorption pipeline is reached;
and the third acquisition unit is used for acquiring a flow signal value in the air intake manifold to acquire an initial flow frequency signal value in the low-pressure desorption pipeline when the carbon tank desorption pipeline flow diagnosis activation condition is reached.
8. The carbon tank desorption line flow diagnostic system of claim 6, wherein the second acquisition module comprises:
and the fourth acquisition unit is used for acquiring a flow frequency signal value with the same frequency as the control frequency of the carbon tank control valve through low-pass filtering processing and high-pass filtering processing.
9. The carbon tank desorption line flow diagnostic system of claim 6, wherein the calculation module comprises:
and the calculating unit is used for calculating the flow signal amplitude in the carbon tank desorption pipeline in the preset time through Fourier transform according to the flow frequency signal value.
10. The carbon tank desorption pipeline flow diagnostic system of claim 6, wherein the first determination module comprises:
a fifth obtaining unit, configured to obtain vehicle operating condition information, where the operating condition information at least includes the following parameters: canister control valve duty cycle, vehicle system voltage, engine speed, ambient temperature, canister control valve frequency, intake manifold pressure, ambient pressure, engine speed, canister control valve duty cycle, and fuel cut-off status;
and the first judgment unit is used for judging whether each parameter in the working condition information reaches a preset condition or not, and if so, reaching the carbon tank desorption pipeline flow diagnosis activation condition.
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