CN101231225A - System and method for determining ethanol content in fuel - Google Patents

Abstract

A system and method are provided for determining an ethanol content of a fuel that is part of a fuel and air mixture combusted within an internal combustion engine. A pressure characteristic of a fuel rail is monitored during operation of the engine. At least one of an effective bulk modulus of the fuel and a pressure perturbation signature is determined based on the pressure characteristic. The ethanol content is determined based on the at least one of the effective bulk modulus and the pressure perturbation signature.

Description

Be used for determining the system and method for ethanol content in fuel

Cross reference to related application

It is the rights and interests of No. the 60/837th, 033, the U.S. Provisional Application on August 11st, 2006 that the application requires the applying date.The open of above-mentioned application is incorporated into this by reference.

The field

The disclosure relates to engine system, and relates more specifically to be used for determining the system and method for ethanol content in fuel.

Background

The statement of this part only provides the background technical information relevant with the disclosure and may not constitute prior art.

Explosive motor produces driving torque by the potpourri of air in the combustion cylinders and fuel.More specifically, air is inhaled in the engine and is assigned in the cylinder.Air and fuel mix, thus ignition mixture formed, it has needed air/fuel ratio, and this potpourri burns in cylinder combustion.Combustion process reciprocally drives the piston in the cylinder, and piston rotation ground drives bent axle, so that driving torque is provided.

Recently, alternative fuel is developed out such as the fuel based on alcohol, for use in engine system.Fuel based on alcohol comprises such as methyl alcohol and ethanol.Modern engine system can be used gasoline, mix arbitrarily and move based on the fuel of alcohol or its.Yet when moving under different fuel situations, the operation of engine must be modified, because the cause of the different qualities of every kind of fuel.Such as, since the cause of different chemical composition, the potpourri of use ethanol or ethanol and gasoline, and (that is the operation of) engine, the potpourri of 85% ethanol and 15% gasoline requires ethanol to increase with respect to the quantity of gasoline on stoichiometry such as E85.

Some engine systems comprise uses the ethanol content of fuel sensor directly to measure.The execution of this fuel sensor has increased the complicacy of integrated cost and engine system.

Other engine system comprises the indirect measurement to ethanol content.More specifically, use the air/fuel ratio calculation to determine the content of ethanol/Fuel Petroleum.This compares the quantity of fuel of Mass Air Flow (MAF) with the injection of being scheduled to and obtain, thereby air/fuel ratio is provided by under stoichiometric conditions of discharge.Use air/fuel ratio to determine that fuel content has good precision, thereby know air/fuel ratio with stoichiometric ethanol, and the air/fuel ratio of gasoline requirement was near 14.5: 1 near 9: 1.

Though virtual (virtual) sensor of current techniques development level can provide the accurate measurement to fuel content, it is consuming time and be easy to mistake and read, because the cause of the influence of a plurality of incoherent engine operational conditions.

Summary

Therefore, the disclosure provides a kind of system and method that is used for the ethanol content of definite fuel, and this fuel is the part of fuel and AIR MIXTURES, and this potpourri is in the explosive motor internal combustion.The pressure characteristic of fuel rail is monitored in the operational process of engine.In the effective bulk modulus of fuel (bulk modulus) at least one and pressure disturbance signal are determined based on pressure characteristic.Ethanol content is based at least one and pressure disturbance signal in the effective bulk modulus and be determined.

In another feature, pressure characteristic comprises at least one in following group, and this group comprises that the pressure that is caused by injection event reduces and increased by the pressure that pumping activities causes.

In another feature, the pressure disturbance signal comprises the mean value corresponding to the pressure amplitude on a plurality of injection/pumping activities.

In another feature, ethanol content calculates based on pressure characteristic.

In another feature, ethanol content is determined from question blank based on the pressure disturbance signal.

In another feature, ethanol content further based in the bulk modulus of the bulk modulus of the volume of the fuel of the volume of the volume of fuel rail, the fuel that sprayed, institute's pumping, gasoline and ethanol at least one and be determined.The bulk modulus of the volume of fuel rail, the bulk modulus of gasoline and ethanol is as the constant of pre-stored and provide.

The disclosure provides a kind of improved virtual fuel content sensor, it has improved existing inducing method by the specific measurement of the fuel system that quick response is provided, reduce the stability (robustness) of (that is, less computation requirement) and improvement to obtain extra logic.

The description that is provided from literary composition, further application will become clear.Be to be understood that: describe and certain embodiments only is used to the purpose explained, and be not limited to the scope of the present disclosure.

Accompanying drawing

Accompanying drawing described in the literary composition only is used to the purpose explained, and never is used for limiting by any way the scope of the present disclosure.

Fig. 1 is the functional-block diagram of exemplary engine system;

Fig. 2 is a figure, has explained according to ethanol content of the present disclosure and has determined the exemplary operational factor track that control is used;

Fig. 3 is a process flow diagram, has explained by ethanol content of the present disclosure and has determined the illustrative steps that control is performed; And

Fig. 4 is the functional-block diagram of example modules, and this module is carried out ethanol content of the present disclosure and determined control.

Describe in detail

Being described in below the preferred embodiment only is exemplary in essence, and never is used to limit the present invention, application of the present invention or use.For the purpose of clear, will use identical label to indicate similar elements in the accompanying drawing.As employed in the text, term module refers to special IC, electronic circuit, processor (shared, special-purpose or in groups) and storer, other suitable member that it is carried out one or more softwares or firmware program, combinational logic circuit or described function is provided.

With reference now to Fig. 1,, it has showed exemplary engine system 10.Exemplary engine system 10 comprises the engine 12 with inlet manifold 14 and exhaust manifold 16.Engine system 10 further comprises the fuel injector system 18 of the fuel injector 22 that (the fuel rail) 20 that have fuel rail and a plurality of and corresponding cylinder 24 are associated.Air is inhaled in the inlet manifold 14 by air throttle 26, and is assigned in the cylinder 24.Air gets up with the fuel mix of spraying by corresponding fuel injector 22, thus cylinder 24 in the formation ignition mixture.Ignition mixture has needed air/fuel ratio, and burns in cylinder combustion, thus driven plunger (figure does not show) reciprocally, and piston drives bent axle 28 again.Waste gas is discharged from engine 12 via exhaust manifold 16.

Fuel system 30 provides fuel for spraying system 18.More specifically, fuel system 30 comprises fuel tank 32 and petrolift 34.Petrolift 34 can be constant displacment pump or variable displacement pump, and provides fuel after the compression for fuel rail 20.When fuel injector 22 injected fuel in the corresponding cylinder 24, the fuel supplement after petrolift 34 will compress was in fuel rail 20.

Control module 40 is determined control and is regulated the operation of engine system 10 based on ethanol content of the present disclosure.More specifically, the fuel pressure in the pressure transducer 42 supervision fuel rail 20.Control module 40 is determined the ethanol content of fuel based on pressure characteristic, as described further below.After determining ethanol content, control module 40 can suitably be regulated air/fuel ratio and other burning controlled variable based on ethanol content.

The disclosure is used predetermined direct injection fuel system content and is determined the ethanol content that fuel is interior.This content comprises volume, and the fuel rail pressure sensor of known fuel rail, and the fuel rail pressure sensor provides as fast response transducer.This content can be used for based on pressure characteristic and determines ethanol content in the fuel.Fig. 2 provides figure, has showed exemplary operational factor track, comprises fuel rail pressure and injection event.

Preferably, when being in steady state (SS), engine and/or fuel rail pressure determine ethanol content.More specifically, steady state (SS) is the operational mode of engine, and average fuel pressure is almost constant in this pattern.Yet if use algorithm based on activity, engine and/or fuel rail pressure do not need to be in steady state (SS) so, and wherein effectively bulk modulus is calculated and is used for any specific pumping activities or injection event.Yet, consider that pressure signal characteristic (that is, from the peak value to the peak value) more long-term or that more simplify may more correspond to reality.In the execution of this simplification, will only be mapped in the size of steady state (SS) benchmark the correlativity of ethanol content.

In a feature, ethanol content is determined in the definite control of ethanol content based on injection event.More specifically, the fuel of predetermined directly is ejected in the cylinder from the fuel rail with known volume.As the result of injection event, hydraulic energy exhausts from fuel rail, and in fuel rail, energy is with the form storage of accumulator.This energy exhausts from fuel rail with the form of the volume that is sprayed with pressure, thereby has caused the lower fuel rail pressure after the injection event.

It is relevant with the bulk modulus (that is the elasticity of fluid) of fluid and the fuel rail volume (that is storage capacity) be scheduled to that pressure in the fuel rail reduces.Because less than the cause of the bulk modulus of gasoline, the pressure that the pressure in the caused fuel rail reduces to cause separately less than gasoline reduces significantly for the bulk modulus of ethanol.When the pressure in the caused fuel rail by injection event reduced, fuel pressure sensor can be used for the gaging pressure characteristic.

Ethanol content is based on injection event and use the following relationship formula and be determined:

${\mathrm{BM}}_{\mathrm{EFFINJ}}=\frac{\mathrm{\Δ}{P}_{\mathrm{INJ}}}{V_{\mathrm{INJ}}}\·V_{\mathrm{RAIL}}---\left(1\right)$

$E_{\mathrm{RATIO}}=100\·\frac{({\mathrm{BM}}_{\mathrm{EFFINJ}}-{\mathrm{BM}}_{\mathrm{GAS}})}{({\mathrm{BM}}_{\mathrm{ETH}}-{\mathrm{BM}}_{\mathrm{GAS}})}\%---\left(2\right)$

Wherein: V _RAILKnown volume for fuel rail;

Δ P _INJFor the pressure as the injection event result reduces;

V _INJVolume for the fuel that sprayed;

BM _EFFINJEffective bulk modulus for injection event;

BM _GASKnown volume modulus for gasoline;

BM _ETHKnown volume modulus for ethanol; And

E _RATIOThe ethanol ratio that provides with number percent is provided.

V _INJCan be according to the following relationship formula and the Be Controlled module calculates as the open loop control item that is used for fuel injector or is used for steady-state condition:

$V_{\mathrm{INJ}}=\frac{3}{4}\·V_{\mathrm{PUMP}}---\left(3\right)$

Wherein: V _PUMPFor being used for the known pump discharge capacity of injection event; And

3/4 is exemplary conversion, has shown four injection event to three pumping activities.

3/4 can be according to the configuration of the configuration of engine and petrolift and change between engine system.V _PUMPCan be used as fixing volume and provide, such as when petrolift is the situation of constant displacment pump, or can be calculated as the open loop control item by control module, it provided before injection event, such as when pump is the situation of variable displacement pump.

In another feature, ethanol content is determined based on pumping activities.More specifically, each pumping activities is reduced to the fuel pressure of predetermined quantity in the fuel rail, thereby causes that pressure increases, and it is directly proportional with the bulk modulus and the known pressure rail volume of fuel again.Ethanol content uses the following relationship formula based on pumping activities and determines:

${\mathrm{BM}}_{\mathrm{EFFPUMP}}=\frac{\mathrm{\Δ}{P}_{\mathrm{PUMP}}}{V_{\mathrm{PUMP}}}\·V_{\mathrm{RAIL}}---\left(4\right)$

$E_{\mathrm{RATIO}}=100\·\frac{({\mathrm{BM}}_{\mathrm{EFFPUMP}}-{\mathrm{BM}}_{\mathrm{GAS}})}{({\mathrm{BM}}_{\mathrm{ETH}}-{\mathrm{BM}}_{\mathrm{GAS}})}\%---\left(5\right)$

Wherein: Δ P _PUMPFor the pressure as the pumping activities result increases; And

BM _EFFPUMPEffective bulk modulus for pumping activities.

In another feature, a plurality of injection event and pumping activities overlap usually in time, thereby produce pressure disturbance (pressure perturbation) signal.The amplitude of disturbing signal is directly proportional with the bulk modulus of fuel again.Therefore, the effective bulk modulus of the bulk modulus of fuel and ethanol/gas and oil content can be in this signal by the gaging pressure perturbation amplitude and evaluated.This measures then and can compare with the question blank of being scheduled to and storing in advance in the control module, and with the function of desired amplitude as volume that is sprayed and/or engine speed, thereby the ethanol content of definite fuel.Such as, the average minimum radius and the amplitude peak of a plurality of burning activities can be determined, and compare with numerical value in the question blank, thereby ethanol content is provided.

With reference now to Fig. 3,, determines that by ethanol content the performed illustrative steps of control will be described in detail.In step 300, control determines whether engine moves.If engine is operation not, then control circulation backward.If engine moves, then be controlled at and determine in the step 302 whether engine runs on steady state (SS).If engine does not run on steady state (SS), then control loops back to step 300.If engine runs on steady state (SS), then be controlled in the step 304 and proceed.

In step 304, control monitors the pressure characteristic of fuel system.Pressure characteristic can comprise that the pressure that the pressure that is caused by injection event reduces, caused by pumping activities increases, and/or includes but not limited to pressure disturbance signal minimum and the amplitude peak value.Be controlled in the step 306 ethanol content of determining based on pressure characteristic in the fuel.More specifically, ethanol content can increase or reduces and/or use question blank directly to calculate based on the pressure disturbance signal based on pressure.In step 308, control system is regulated the operation of engine based on ethanol content.Such as, control system is adjusted the calculating of air/fuel ratio, electronic spark advance and valve timing based on ethanol content.

With reference now to Fig. 4,, determines that by ethanol content the example modules that control system is carried out will be described in detail.Exemplarily module is included in first module 400 that monitors the pressure characteristic of fuel rail in the operational process of engine, and determines the effective bulk modulus of fuel and at least one second module 402 in the pressure disturbance signal based on pressure characteristic.Three module 404 based on the effective bulk modulus of fuel and in the pressure disturbance signal at least one and determine ethanol content in the fuel, as above described in detail.Four module 406 is regulated the operation of engine based on ethanol content.

Those those of ordinary skill in the art can understand now from the foregoing description: wide in range instruction of the present invention can be carried out in a variety of forms.Though therefore the present invention is described in conjunction with its certain embodiments, true scope of the present invention should not be so limited, because according to the research to accompanying drawing, instructions and following claim, other modification will be apparent to the practitioner with certain technology.

Claims (21)

1. the method for a definite ethanol content in fuel, described fuel is the part of fuel and AIR MIXTURES, and described potpourri is in the explosive motor internal combustion, and described method comprises:

In the operational process of described engine, monitor the pressure characteristic of fuel rail;

Determine the effective bulk modulus of described fuel and at least one in the pressure disturbance signal based on described pressure characteristic; And

Based in described effective bulk modulus and the described pressure disturbance signal at least one and determine the content of described ethanol.

2. the method for claim 1 is characterized in that, described pressure characteristic comprises at least one in following group, and described group comprises that the pressure that is caused by injection event reduces and increased by the pressure that pumping activities causes.

3. the method for claim 1 is characterized in that, described pressure disturbance signal comprises the mean value corresponding to the pressure amplitude in a plurality of burning activities.

4. the method for claim 1 is characterized in that, described ethanol content calculates based on described pressure characteristic.

5. the method for claim 1 is characterized in that, described ethanol content is determined from question blank based on described pressure disturbance signal.

6. the method for claim 1, it is characterized in that, described ethanol content further based in the bulk modulus of the bulk modulus of the volume of the fuel of the volume of the volume of fuel rail, the fuel that sprayed, institute's pumping, gasoline and ethanol at least one and be determined.

7. method as claimed in claim 6 is characterized in that, the bulk modulus of the volume of described fuel rail, the bulk modulus of described gasoline and described ethanol is as the constant of pre-stored and provide.

8. system that is used for determining the ethanol content of fuel, described fuel is the part of fuel and AIR MIXTURES, and described potpourri is in the explosive motor internal combustion, and described system comprises:

First module, it monitors the pressure characteristic of fuel rail in the operational process of described engine;

Second module, it determines the effective bulk modulus of described fuel and at least one in the pressure disturbance signal based on described pressure characteristic; And

Three module, its based in described effective bulk modulus and the described pressure disturbance signal at least one and determine described ethanol content.

9. system as claimed in claim 8 is characterized in that described pressure characteristic comprises at least one in following group, and described group comprises that the pressure that is caused by injection event reduces and increased by the pressure that pumping activities causes.

10. system as claimed in claim 8 is characterized in that, described pressure disturbance signal comprises the mean value corresponding to the pressure amplitude in a plurality of burning activities.

11. system as claimed in claim 8 is characterized in that, described ethanol content calculates based on described pressure characteristic.

12. system as claimed in claim 8 is characterized in that, described ethanol content is determined from question blank based on described pressure disturbance signal.

13. system as claimed in claim 8, it is characterized in that, described ethanol content further based in the bulk modulus of the bulk modulus of the volume of the fuel of the volume of the volume of fuel rail, the fuel that sprayed, institute's pumping, gasoline and ethanol at least one and be determined.

14. system as claimed in claim 13 is characterized in that, the bulk modulus of the volume of described fuel rail, the bulk modulus of described gasoline and described ethanol is as the constant of pre-stored and provide.

15. the method for the ethanol content of definite fuel, described fuel are the part of fuel and air mixture, described potpourri is in the explosive motor internal combustion, and described method comprises:

In the operational process of described engine, monitor the pressure characteristic of fuel rail;

Assess described engine and whether run on steady-state mode;

When described engine runs on described steady-state mode, determine the effective bulk modulus of described fuel and at least one in the pressure disturbance signal based on described pressure characteristic;

Based in described effective bulk modulus and the described pressure disturbance signal at least one and determine the content of described ethanol; And

Regulate the operation of described engine based on described ethanol content.

16. method as claimed in claim 15 is characterized in that, described pressure characteristic comprises at least one in following group, and described group comprises that the pressure that is caused by injection event reduces and increased by the pressure that pumping activities causes.

17. method as claimed in claim 15 is characterized in that, described pressure disturbance signal comprises the mean value corresponding to the pressure amplitude in a plurality of burning activities.

18. method as claimed in claim 15 is characterized in that, described ethanol content calculates based on described pressure characteristic.

19. method as claimed in claim 15 is characterized in that, described ethanol content is determined from question blank based on described pressure disturbance signal.

20. method as claimed in claim 16, it is characterized in that, described ethanol content further based in the bulk modulus of the bulk modulus of the volume of the fuel of the volume of the volume of fuel rail, the fuel that sprayed, institute's pumping, gasoline and ethanol at least one and be determined.

21. method as claimed in claim 20 is characterized in that, the bulk modulus of the volume of described fuel rail, the bulk modulus of described gasoline and described ethanol provides as the constant of pre-stored.

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