CN107886593A - A kind of computational methods of fuel tank discharge vaporization leak diagnostics inspection policies - Google Patents
A kind of computational methods of fuel tank discharge vaporization leak diagnostics inspection policies Download PDFInfo
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- 239000002828 fuel tank Substances 0.000 title claims abstract description 125
- 238000009834 vaporization Methods 0.000 title claims abstract description 19
- 230000008016 vaporization Effects 0.000 title claims abstract description 19
- 238000007689 inspection Methods 0.000 title claims abstract description 15
- 238000000205 computational method Methods 0.000 title claims abstract description 14
- 238000001514 detection method Methods 0.000 claims abstract description 27
- 238000000034 method Methods 0.000 claims abstract description 11
- 238000007906 compression Methods 0.000 claims abstract description 6
- 230000008569 process Effects 0.000 claims abstract description 6
- 230000006835 compression Effects 0.000 claims abstract description 5
- 238000005273 aeration Methods 0.000 claims description 8
- 238000004364 calculation method Methods 0.000 claims description 4
- 239000000446 fuel Substances 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 3
- 239000012530 fluid Substances 0.000 claims description 3
- 230000000704 physical effect Effects 0.000 claims description 3
- 239000000295 fuel oil Substances 0.000 abstract description 6
- 238000011217 control strategy Methods 0.000 abstract 1
- 238000004134 energy conservation Methods 0.000 abstract 1
- 238000002347 injection Methods 0.000 abstract 1
- 239000007924 injection Substances 0.000 abstract 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 8
- 230000008859 change Effects 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 238000012544 monitoring process Methods 0.000 description 4
- 239000003921 oil Substances 0.000 description 3
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 235000013399 edible fruits Nutrition 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000010761 intermediate fuel oil Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000012806 monitoring device Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- G—PHYSICS
- G07—CHECKING-DEVICES
- G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
- G07C5/00—Registering or indicating the working of vehicles
- G07C5/08—Registering or indicating performance data other than driving, working, idle, or waiting time, with or without registering driving, working, idle or waiting time
- G07C5/0808—Diagnosing performance data
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Abstract
A kind of computational methods of fuel tank discharge vaporization leak diagnostics inspection policies, based on conventional fuel oil case leak detection means, that is air compressor injecting compressed air into fuel tank to be hunted leak, controlled computer record current of electric by automobile in gas replenishment process and electric current is surveyed by the standard leak in benchmark 0.5mm apertures with compressed air and contrasted, so as to judge that fuel tank whether there is the leakage aperture more than 0.5mm.Leak detection stage compression air injects the control strategy of fuel tank time：Car running computer detects and gathers air compressor flow, fuel oil the temperature inside the box and steam pressure, time is calculated required for being inflated to pressure balance in fuel tank since fuel tank according to fuel tank mass-conservation equation, energy conservation equation and leakage equation, and be fed back to motor, with this come control leak detection during compressed air injection motor the time required to.The present invention can improve the accuracy of discharge vaporization leak diagnostics.
Description
Technical field
The present invention relates to fuel tank leak diagnostics detection field, and in particular to a kind of fuel tank discharge vaporization leak diagnostics inspection
The computational methods of strategy are surveyed, accurate control is made to the inflation during actual hunt leak and detection time, improves the accurate of diagnosis
Property.
Background technology
Running car for a period of time after, fuel tank can because of higher environment temperature and fuel tank intermediate fuel oil pump power
The heat of generation is lost, produces some hydrocarbon vapors.When minute leakage in fuel tank be present, these steam pass through leak
It is discharged into environment, forms evaporative emission thing, this can causes very big harm to environment, while be also a kind of wave of resource
Take.
At present, existing many countries formulate and have put into effect quite strict automobile environment-protection discharge policy to limit these evaporations
Thing discharges, and the California Air resource committee is in the regulation of newest appearance, it is desirable to detects equivalent to 0.5mm aperture
Steam is leaked, and its testing result is fed back into automotive engine control ECU, and implements fault alarm prompting to car owner, with reality
When monitor fuel tank and leak exceeded situation.China also performed GB18352.5-2013 in China on January 1st, 2017
《Light-duty vehicle pollutant emission limiter stage measuring method (Chinese 5th stage)》, also increase in file to evaporate fuel tank and arrange
The inspection requirements put, promote automaker to make further improve to product technology and upgrade.
In order to limit the discharge of the minute leakage of hydrocarbon vapor in fuel tank, a kind of method is installation combustion in the car
Fuel tank leak diagnostics module, the diagnostic module can identify (to be exceeded in whole fuel oil box ventilation system with the presence or absence of minor leakage
0.5mm apertures) and significant leakage (more than 1mm apertures), and shown by malfunction indicator lamp.Whether detection fuel tank system leaks
Method be：First, air compressor sets up one equivalent to reference to gauge pressure of the leakage rate for 0.5mm apertures and maintenance
For a period of time, and the pump electric current of this gauge pressure will be maintained as reference current value；Then, by this compressor to fuel oil to be measured
Inflated in case, in the pressurization then carried out, record surveys pump current value and compared with reference current value, such as
Fruit has declined compared with reference current value, illustrates the signal of leakage in fuel tank system be present, if it exceeds reference current value
Shi Ze shows not leak in system.However, in air compressor to fuel tank aeration phase, how according to actual environment and difference
Working conditions of compressor be precisely controlled inflation and detection time be also a technical barrier.
The content of the invention
It is an object of the invention to for above-mentioned the problems of the prior art, there is provided a kind of fuel tank discharge vaporization leakage is examined
The computational methods of disconnected inspection policies, to applying to the detection plan of the leak diagnostics in fuel tank of vehicle discharge vaporization leak diagnostics module
Slightly, under the conditions of the actual environment residing for fuel tank, by calculating, during inflation and detection during the accurate actual leak detection of control
Between, to realize the accuracy of discharge vaporization leak diagnostics, so as to optimize the application of discharge vaporization leak diagnostics inspection policies.
To achieve these goals, the technical solution adopted by the present invention comprises the following steps：
S1：Fuel tank to be detected is reduced to open loop system, calculates the leakage rate and fuel tank mass leakage of fuel tank
Rate；
S2：In air compressor to fuel tank aeration phase, according to the air inlet rate of fuel tank and the exhaust rate of compressor,
The delivery temperature of compressor is calculated, further according to Engineering Thermodynamics law, draws the air inlet enthalpy of fuel tank and the enthalpy of oil and gas leakage
Value；
S3：The mass-conservation equation of fuel tank is established, and combines fuel tank mass M after inflationbCalculation relational expression：
And cavity internal pressure calculation formula
Compressor aeration phase, time t used when fuel tank pressure keeps balancing are tried to achieve, i.e. leak detection needs the time；
In formula, MoFor the intrinsic quality of fuel tank, minFor fuel tank air inlet rate and compressor air-discharging rate, moutFor fuel tank
The slip of oil gas, R are gas constant, T0For gas temperature, VbFor fuel tank cavity volume.
Fuel tank discharge vaporization leak diagnostics inspection policies are notes after inflating a period of time into fuel tank from air compressor
Record drives the motor current value of compressor, and surveys pump current value by 0.5mm benchmark opening by aperture with air pump and enter
Row contrast, judge that fuel tank whether there is more than diameter 0.5mm fuel leakage according to comparing result.
In described step S1, fuel tank inside and outside differential pressure Δ P and leakage rate vbRelation be：
The leakage rate of fuel tank is：
According to the leakage aperture D of fuel tankb, fuel tank mass leakage rate is expressed as：
In formula, ρbFor fluid density, ξbFor leadage coefficient.
In described step S2, during compressor compresses, intake air temperature T0It is T with delivery temperatureinThere is following relation：
That is the delivery temperature of compressor is：
N in formula is according to compressor actual inside compression thermodynamic process in 1~1.4 value；
Temperature is that T air enthalpy h is expressed as：
H=f (T, d)
D in formula be per kg dry air in the steam quality that contains, unit kg/kg；Fuel tank air inlet enthalpy table
It is shown as：hin=f (Tin, d), its occurrence is inquired about thermal physical property parameter table or is calculated by its correlation formula；
houtFor the enthalpy of fuel tank oil and gas leakage, hout=f (Tout,d)。
In described step S3, the mass-conservation equation for establishing fuel tank is as follows：
In formula, hbFor fuel tank enthalpy, h after inflationoFor the intrinsic enthalpy of fuel tank.
The mass-conservation equation of fuel tank internal gas is solved using Fourth order Runge-Kutta, specific computational methods are such as
Under：
In above formulaGaseous mass in fuel tank when being iteration i steps,Gaseous mass in fuel tank when being iteration i+1 steps,
tiTime when being the i-th step of iteration, Δ t are iteration time step-lengths；
With reference to leakage rate solution formula：
Time used is tried to achieve when fuel tank pressure keeps balancing by iteration, i.e. leak detection needs the time.
Compared with prior art, the present invention has following beneficial effect：The leakage of fuel tank evaporative emission control system is examined
During disconnected monitoring, fresh air air inlet compressor, air compressor is by motor driven.Wherein, air compressor start and stop are electricity
The start and stop of machine are controlled by car running computer ECU.Exit gas after air compressor compression is divided into two-way, passes through standard all the way
A diameter of 0.5mm reference leak-testing hole, another way then after activated carbon canister, are passed through in the fuel tank leak diagnostics monitoring stage
Flowmeter enters fuel tank and completes inflation work.Car running computer ECU is responsible for gathering current of electric, fuel tank used in air compressor
Air inlet flow and fuel tank inner tank liquid level, pressure signal, while control the air compressor duration of runs.Car running computer
ECU can be calculated by the present invention under different environmental working conditions and be set detection leakage stage air pump and inflated to fuel pump
Time used, accurate control is made to the inflation during actual hunt leak and detection time, to realize discharge vaporization leak diagnostics
Accuracy so that compressor inflation leak hunting method more easily apply in practice.
Further, the present invention solves the mass-conservation equation of fuel tank using Fourth order Runge-Kutta, and precision is higher.
Brief description of the drawings
Fig. 1 fuel tank discharge vaporization leak diagnostics detecting system schematic diagrams；
In figure：1. air pump fresh air inlet；2. air compressor；3. motor；4.0.5mm with reference to leak-testing hole；
5. activated carbon canister；6. engine chamber connecting line；7. fuel tank；8. leak；9. flowmeter；10. fuel oil intake valve；
11. triple valve.
Embodiment
The present invention is described in further detail below in conjunction with the accompanying drawings.
Referring to Fig. 1, when fuel tank evaporative emission control system leak diagnostics monitor, fresh air is through air pump fresh air
The air inlet compressor 2 of entrance 1, air compressor 2 are driven by motor 3.Wherein, the start and stop of air compressor 2 are the start and stop of motor 3
Then controlled by car running computer ECU.Exit gas after air compressor 2 compresses is divided into two-way, a-road-through after triple valve 11
Cross 0.5mm and refer to leak-testing hole 4, after activated carbon canister 5, the stage then is monitored through inflow-rate of water turbine in fuel tank leak diagnostics for another way
Meter 9 enters fuel tank 7 and completes inflation work.Car running computer ECU is responsible for gathering current of electric, fuel tank used in air compressor 2
Air inlet flow and fuel tank inner tank liquid level and pressure signal, while control the duration of runs of air compressor 2.
Its specific monitoring policy is：
1) closing automobile engine, by other monitoring devices of car running computer, whether monitoring driving meets that driving voltage exists
9-16V, ambient pressure be more than 730hPa, engine higher than 5 DEG C, intake air temperature higher than 5 DEG C simultaneously fluctuation less than 12 DEG C, automobile compared with
Traveling, the speed condition such as between 3-150km/h at part load for a long time；
If 2) meet that the detection in step 1 performs prerequisite, then pneumatic leak detection module startup optimization, goes first
Car computer ECU closes fuel oil intake valve 10, cuts off compressed air and fuel-steam enters automobile engine；
3) car running computer ECU persistently detects the temperature variations of the vapor space in fuel tank 7.
Within a certain period of time, temperature change terminates leak detection module if certain value is exceeded in fuel tank 7.Reason is temperature
Degree has a great impact to the vapour pressure in fuel tank 7, if the vapour pressure change in detection time section in fuel tank 7 is too greatly, meeting
Cause detection time program to calculate and larger error occur, leak diagnostics may be caused to judge by accident；
4) start motor driven air compressor 2 to operate, car running computer ECU control triple valves 11 cause compressed gas to pass through
0.5mm refers to leak-testing hole, maintains this process 10-15s, ECU to record current of electric as leak detection reference current value；
5) after normal reference current record, car running computer ECU regulating three-way valves 11 cause compressed gas to pass through activated carbon canister 5
The leak detection stage is completed into fuel tank 7.During this period, ECU can gather the compressed air require into fuel tank 7 and combustion
Temperature and steam pressure in fuel tank, air compressor inflationtime is calculated by the present invention, and be fed back to motor, with this
Control actual inflationtime.The computational methods of the present invention comprise the following steps：
Fuel tank to be detected is reduced to an open loop system, fuel tank cavity volume is Vb, density ρb, empty cavity pressure Pb,
Atmospheric pressure is P0, leadage coefficient ξb, according to fluid mechanics knowledge, fuel tank inside and outside differential pressure Δ P and leakage rate vbRelation be：
The leakage rate of fuel tank is：
According to the leakage aperture D of fuel tankb, then fuel tank mass leakage rate be：
In air compressor to fuel tank aeration phase, fuel tank air inlet rate and compressor air-discharging rate are min；In compressor
In compression process, intake air temperature T0, delivery temperature Tin, according to thermal procession, there is following relation therebetween：
That is the delivery temperature of compressor is：
N value depends on compressor actual inside compression thermodynamic process herein, and n suggestion value is 1-1.4.
Gained knowledge according to engineering thermal, temperature is that T air enthalpy h can be expressed as：
hin=f (T, d)；
In formula, d is the steam quality (kg/kg) contained in every kg dry air.Then fuel tank air inlet enthalpy can represent
For：hin=f (Tin, d), its occurrence can inquire about thermal physical property parameter table or is calculated by its correlation formula.
Using fuel tank as open loop system, mass-conservation equation is established：
In formula, MbAnd hbFuel tank mass change and enthalpy variable quantity in respectively certain aeration phase, and MoAnd hoRespectively
For the intrinsic quality of fuel tank and enthalpy.Meanwhile fuel tank mass change amount MbAlso following relation is met：
In addition, being gained knowledge according to heating power, also there is following relational expression in fuel tank：
Wherein T0For gas temperature.
, can be in the hope of compressor aeration phase, when fuel tank pressure is used when keeping balance according to relation above formula
Between, it that is to say time value used in the suggestion of fuel tank leak detection.Specific solution procedure is as follows：
For differential equation, standard quality conservation equation is solved using Fourth order Runge-Kutta, i.e.,：
With reference to leakage rate solution formula：
Time used is tried to achieve when fuel tank pressure keeps balancing by iteration, i.e. leak detection needs the time.
6) change over time process in leak detection stage record current of electric, and with benchmark leak detection reference current value
Contrasted.If recognizing electric current compared with the reference current previously measured to have declined, here it is deposited in fuel system
In the signal of leakage；If it exceeds show not leak in system during reference current.
The purpose of the present invention, technical scheme and beneficial effect are described in detail above content, should be understood that
It is that the foregoing is only a kind of embodiment of the invention, the protection domain being not intended to limit the present invention.It is all in this hair
Within bright spirit and principle, any modification, equivalent substitution and improvement for being made etc., the scope of the present invention should be included in
Within.
Claims (6)
1. a kind of computational methods of fuel tank discharge vaporization leak diagnostics inspection policies, it is characterised in that comprise the following steps：
S1：Fuel tank to be detected is reduced to open loop system, calculates the leakage rate and fuel tank mass leakage rate of fuel tank；
S2：In air compressor to fuel tank aeration phase, according to the air inlet rate of fuel tank and the exhaust rate of compressor, calculate
The delivery temperature of compressor, further according to Engineering Thermodynamics law, draw the air inlet enthalpy of fuel tank and the enthalpy of oil and gas leakage；
S3：The mass-conservation equation of fuel tank is established, and combines fuel tank mass M after inflationbCalculation relational expression：
And cavity internal pressure calculation formula
Compressor aeration phase, time t used when fuel tank pressure keeps balancing are tried to achieve, i.e. leak detection needs the time；
In formula, MoFor the intrinsic quality of fuel tank, minFor fuel tank air inlet rate and compressor air-discharging rate, moutFor fuel tank oil gas
Slip, R is gas constant, T0For gas temperature, VbFor fuel tank cavity volume.
2. the computational methods of fuel tank discharge vaporization leak diagnostics inspection policies according to claim 1, it is characterised in that：
Fuel tank discharge vaporization leak diagnostics inspection policies are record papers after inflating a period of time into fuel tank from air compressor
The motor current value of dynamic compressor, and pump current value is surveyed by 0.5mm benchmark opening by aperture with air pump and carried out pair
Than judging that fuel tank whether there is more than diameter 0.5mm fuel leakage according to comparing result.
3. the computational methods of fuel tank discharge vaporization leak diagnostics inspection policies according to claim 1, it is characterised in that
In described step S1, fuel tank inside and outside differential pressure Δ P and leakage rate vbRelation be：
<mrow>
<mi>&Delta;</mi>
<mi>P</mi>
<mo>=</mo>
<mfrac>
<mn>1</mn>
<mn>2</mn>
</mfrac>
<msub>
<mi>&xi;</mi>
<mi>b</mi>
</msub>
<msub>
<mi>&rho;</mi>
<mi>b</mi>
</msub>
<msubsup>
<mi>v</mi>
<mi>b</mi>
<mn>2</mn>
</msubsup>
<mo>;</mo>
</mrow>
The leakage rate of fuel tank is：
<mrow>
<msub>
<mi>v</mi>
<mi>b</mi>
</msub>
<mo>=</mo>
<msqrt>
<mfrac>
<mrow>
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<mi>&Delta;</mi>
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<mi>&rho;</mi>
<mi>b</mi>
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</msqrt>
<mo>;</mo>
</mrow>
According to the leakage aperture D of fuel tankb, fuel tank mass leakage rate is expressed as：
<mrow>
<msub>
<mi>m</mi>
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</msub>
</mfrac>
</msqrt>
<mo>;</mo>
</mrow>
In formula, ρbFor fluid density, ξbFor leadage coefficient.
4. the computational methods of fuel tank discharge vaporization leak diagnostics inspection policies according to claim 1, it is characterised in that
In described step S2, during compressor compresses, intake air temperature T0It is T with delivery temperatureinThere is following relation：
<mrow>
<mfrac>
<msub>
<mi>T</mi>
<mrow>
<mi>i</mi>
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<mo>-</mo>
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<mi>n</mi>
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</msup>
<mo>;</mo>
</mrow>
That is the delivery temperature of compressor is：
<mrow>
<msub>
<mi>T</mi>
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N in formula is according to compressor actual inside compression thermodynamic process in 1~1.4 value；
Temperature is that T air enthalpy h is expressed as：
H=f (T, d)
D in formula be per kg dry air in the steam quality that contains, unit kg/kg；Fuel tank air inlet enthalpy is expressed as：
hin=f (Tin, d), its occurrence is inquired about thermal physical property parameter table or is calculated by its correlation formula；
houtFor the enthalpy of fuel tank oil and gas leakage, hout=f (Tout,d)。
5. the computational methods of fuel tank discharge vaporization leak diagnostics inspection policies according to claim 1, it is characterised in that
In described step S3, the mass-conservation equation for establishing fuel tank is as follows：
<mrow>
<msub>
<mi>M</mi>
<mi>b</mi>
</msub>
<msub>
<mi>h</mi>
<mi>b</mi>
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In formula, hbFor fuel tank enthalpy, h after inflationoFor the intrinsic enthalpy of fuel tank.
6. according to the computational methods of the fuel tank discharge vaporization leak diagnostics inspection policies of claim 1 or 5, its feature exists
In as follows using the mass-conservation equation of Fourth order Runge-Kutta solution fuel tank internal gas, specific computational methods：
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<mrow>
<mo>(</mo>
<msup>
<mi>t</mi>
<mi>i</mi>
</msup>
<mo>+</mo>
<mfrac>
<mrow>
<mi>&Delta;</mi>
<mi>t</mi>
</mrow>
<mn>2</mn>
</mfrac>
<mo>,</mo>
<msubsup>
<mi>M</mi>
<mi>b</mi>
<mi>i</mi>
</msubsup>
<mo>+</mo>
<mfrac>
<mrow>
<mi>&Delta;</mi>
<mi>t</mi>
</mrow>
<mn>2</mn>
</mfrac>
<msub>
<mi>k</mi>
<mn>1</mn>
</msub>
<mo>)</mo>
</mrow>
</mrow>
</mtd>
</mtr>
<mtr>
<mtd>
<mrow>
<msub>
<mi>k</mi>
<mn>3</mn>
</msub>
<mo>=</mo>
<mi>f</mi>
<mrow>
<mo>(</mo>
<msup>
<mi>t</mi>
<mi>i</mi>
</msup>
<mo>+</mo>
<mfrac>
<mrow>
<mi>&Delta;</mi>
<mi>t</mi>
</mrow>
<mn>2</mn>
</mfrac>
<mo>,</mo>
<msubsup>
<mi>M</mi>
<mi>b</mi>
<mi>i</mi>
</msubsup>
<mo>+</mo>
<mfrac>
<mrow>
<mi>&Delta;</mi>
<mi>t</mi>
</mrow>
<mn>2</mn>
</mfrac>
<msub>
<mi>k</mi>
<mn>2</mn>
</msub>
<mo>)</mo>
</mrow>
</mrow>
</mtd>
</mtr>
<mtr>
<mtd>
<mrow>
<msub>
<mi>k</mi>
<mn>4</mn>
</msub>
<mo>=</mo>
<mi>f</mi>
<mrow>
<mo>(</mo>
<msup>
<mi>t</mi>
<mi>i</mi>
</msup>
<mo>+</mo>
<mi>&Delta;</mi>
<mi>t</mi>
<mo>,</mo>
<msubsup>
<mi>M</mi>
<mi>b</mi>
<mi>i</mi>
</msubsup>
<mo>+</mo>
<msub>
<mi>&Delta;tk</mi>
<mn>3</mn>
</msub>
<mo>)</mo>
</mrow>
</mrow>
</mtd>
</mtr>
</mtable>
</mfenced>
<mo>;</mo>
</mrow>
In above formulaGaseous mass in fuel tank when being iteration i steps,Be iteration i+1 step when fuel tank in gaseous mass, tiIt is
Time during the i-th step of iteration, Δ t are iteration time step-lengths；
With reference to leakage rate solution formula：
<mrow>
<msub>
<mi>m</mi>
<mrow>
<mi>o</mi>
<mi>u</mi>
<mi>t</mi>
</mrow>
</msub>
<mo>=</mo>
<mfrac>
<mi>&pi;</mi>
<mn>4</mn>
</mfrac>
<msubsup>
<mi>D</mi>
<mi>b</mi>
<mn>2</mn>
</msubsup>
<msqrt>
<mfrac>
<mrow>
<mn>2</mn>
<msub>
<mi>&Delta;P&rho;</mi>
<mi>b</mi>
</msub>
</mrow>
<msub>
<mi>&xi;</mi>
<mi>b</mi>
</msub>
</mfrac>
</msqrt>
<mo>=</mo>
<mfrac>
<mi>&pi;</mi>
<mn>4</mn>
</mfrac>
<msubsup>
<mi>D</mi>
<mi>b</mi>
<mn>2</mn>
</msubsup>
<msqrt>
<mfrac>
<mrow>
<mn>2</mn>
<msub>
<mi>&Delta;PP</mi>
<mi>b</mi>
</msub>
</mrow>
<mrow>
<msub>
<mi>&xi;</mi>
<mi>b</mi>
</msub>
<msub>
<mi>RT</mi>
<mi>b</mi>
</msub>
</mrow>
</mfrac>
</msqrt>
</mrow>
Time used is tried to achieve when fuel tank pressure keeps balancing by iteration, i.e. leak detection needs the time.
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| CN110230547A (en) * | 2019-05-27 | 2019-09-13 | 江苏大学 | A kind of vehicle-mounted fuel leakage detection method and its detection system |
| CN110774889A (en) * | 2019-10-25 | 2020-02-11 | 吉利汽车研究院（宁波）有限公司 | Method and system for detecting whether fuel tank cover is closed or not and automobile |
| CN111350598A (en) * | 2020-02-21 | 2020-06-30 | 吉利汽车研究院（宁波）有限公司 | Dual-fuel leakage diagnosis system and diagnosis method thereof |
| CN113237616A (en) * | 2021-04-15 | 2021-08-10 | 江苏大学 | Combined detection system and method for leakage of automobile fuel evaporation system |
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| CN111350598A (en) * | 2020-02-21 | 2020-06-30 | 吉利汽车研究院（宁波）有限公司 | Dual-fuel leakage diagnosis system and diagnosis method thereof |
| CN113237616A (en) * | 2021-04-15 | 2021-08-10 | 江苏大学 | Combined detection system and method for leakage of automobile fuel evaporation system |
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