CN104165100A - Method for removing influence on engine from COG component instability - Google Patents

Abstract

The invention provides a method for removing influence on an engine from COG component instability. COG with fixed components is used as standard gas, through experiments, various control parameters of an engine are calibrated, and optimum control is achieved. Small tank H2, CH4 and CO standard gas is externally connected. When the components of the COG are changed, the temperature, the pressure and the density of current gas are measured through temperature, pressure and gas density sensors arranged in a COG tank for a vehicle, the volume fractions of the components of practical COG are detected through H2, CH4 and CO sensors, the mass fractions of the components of the practical COG are obtained by computing, and by comparing with the mass fractions of the components of the stand COG, a control strategy is selected. According to an engine working condition, the jetting amounts of the practical COG, H2, CH4 and CO are controlled respectively. According to the method, through a COG component correcting algorithm, the components are corrected, and engine self-adaptation control speed during COG component changing is increased.

Description

A kind of method of COG component unstability on motor impact of eliminating

Technical field

The invention belongs to motor field of engineering technology, relate to a kind of for eliminating the method for COG component unstability on motor impact.Be applicable to the current COG motor by gasoline engine refitting, can realize in the time of COG change of component, motor, by adjusting fuel gas injection, is realized optimal control fast and accurately.

Background technique

Along with the fast development of automotive industry, its huge energy consumption has threatened national the energy safety of supply, and meanwhile, a large amount of tail gas of discharge have also directly threatened ecotope and human health.Clean Vehicle Alternative Fuels has become the important topic of various countries' research, wherein Aalcohols fuel and gaseous fuel are most widely used substitute fuels, but than Aalcohols fuel, gaseous fuel occupies huge advantage in all many-sides such as resource, economy, discharge, safety, is the first-selected substitute fuel of current automobile.In conjunction with China's national situation, COG is a kind of desirable clean alternative fuel.

At present, COG motor is directly improved on the basis of petrol engine, has retained the control strategy of petrol engine, searches MAP figure according to duty parameters such as throttle opening, suction pressure and engine speed, determines injection pulse width and the ignition advance angle of fuel.In this control strategy, the parameters such as air fuel ratio, ignition advance angle can, by closed-loop feedback control, realize the accurate control in more among a small circle, but its control rate be limited, is not suitable for parameter and changes huge situation.In actual conditions, the each constituent content of COG and coal for coking quality and coking condition are closely related, have very large enterprise, region and production batch otherness.The unstability of COG component, the great variety of actual mixing ratio and combustion characteristic will be caused, make control system for internal combustion engine target air-fuel ratio and ignition advance angle not there is all the time optimality, thereby had a strong impact on the properties such as the power character, Economy, maneuverability of motor.

Summary of the invention

The object of the invention is to propose the method for a kind of COG of elimination component unstability on motor impact.Adopt the fixing COG of a kind of component as Standard Gases, by experiment, each control parameter of motor is demarcated, realize optimal control.External canister H ₂, CH ₄with CO Standard Gases, in the time that COG component changes, by being arranged on temperature, pressure and the density of temperature in the automobile-used gas tank of COG, pressure, the current gas of gas density sensor measurement, pass through H ₂, CH ₄detect the volume fraction of the each component of actual COG with CO sensor, and by calculating the mass fraction of the each component of actual COG, by comparing with each constituent mass mark of standard C OG, select control strategy.According to engine operating condition, control respectively actual COG, H ₂, CH ₄with the emitted dose of CO, make the fuel gas mixture COG that is near the mark as far as possible, realize the optimal control of COG engine combustion.

Technological scheme of the present invention: the present invention is the method for a kind of COG of elimination component unstability on motor impact, the steps include:

The first step: choose the fixing COG of a kind of component as Standard Gases, its H ₂, CH ₄be respectively with the mass fraction of CO with massfraction _cO, the method such as by experiment, respectively controls parameter to motor to demarcate, and realizes optimal control.

Second step: by being arranged on the H in COG gas tank ₂, CH ₄with CO sensor, measure the volume fraction of the above-mentioned three kinds of components of actual COG with molefraction' _cO, and measure temperature T, pressure p and the density p of current gas by temperature, pressure, gas densitometer.

The 3rd step: according to above-mentioned parameter, calculate the mass fraction of the each component of actual COG with massfraction' _cO, according to the air inflow m of current working _a, air fuel ratio α, and each constituent mass mark of standard C OG and actual COG, by COG component correction algorithm, calculates actual COG, H ₂, CH ₄with the emitted dose of CO, realize the optimal control of COG engine combustion.

Beneficial effect of the present invention is:

(1) the present invention, by COG component correction algorithm, revises each component, instead of by closed-loop feedback control, the parameter such as air fuel ratio, ignition advance angle is revised, and has improved the speed of engine self-adaptive control when COG component changes.

(2) the present invention is by revising component, and mock standard COG as far as possible, has eliminated the impact of change of component on air fuel ratio, combustion characteristic etc., can realize optimal control.

(3) controlling method that the present invention proposes can be carried out under all operating modes, and the moment ensures the optimal control of motor, and then ensures the properties of motor operation.

Brief description of the drawings

Fig. 1 adopts COG engine control block diagram of the present invention.

Fig. 2 is the main flow chart of a kind of COG of elimination component unstability on component correction algorithm in the method for motor impact.

Embodiment

Below in conjunction with accompanying drawing, the invention will be further described.

Fig. 1 adopts COG engine control block diagram of the present invention.

COG motor is to improve on the basis of petrol engine, it has adopted the original control strategy of petrol engine, gather engine operating condition data by signal gathering unit, and be transferred to ECU control unit, obtain the parameters such as air input of engine by air by searching MAP figure, and then control the parameters such as fuel injection.This control block diagram has increased COG component Correction and Control algoritic module on the basis of former control strategy, by the method for mock standard COG component, has improved the control rate of motor when Gas Components changes, and has realized the optimal control of motor operation.

Fig. 2 is the main flow chart of a kind of COG of elimination component unstability on component correction algorithm in the method for motor impact.

The first step: according to the parameter of the actual COG of each sensor measurement in COG gas tank, calculate the mass fraction of the each component of actual COG, its formula is as follows.The volume fraction of above-mentioned three kinds of components with molefraction' _cO, and measure temperature T, pressure p and the density p of current gas by temperature, pressure, gas densitometer, wherein R is ideal gas constant, represent H ₂molal weight, represent CH ₄molal weight, M _cOrepresent CO molal weight.

$\mathrm{pV}=\mathrm{nRT}=\frac{m}{\stackrel{\‾}{M}}\mathrm{RT}=\frac{\mathrm{\ρV}}{\stackrel{\‾}{M}}\mathrm{RT}$

$\begin{array}{c}\stackrel{\‾}{M}=\frac{\mathrm{\ρ}}{p}\mathrm{RT}\\ {\mathrm{massfraction}}_{H_2}^{\′}=\frac{M_{H_2}\×{\mathrm{molefraction}}_{H_2}^{\′}}{\stackrel{\‾}{M}}\\ {\mathrm{massfraction}}_{{\mathrm{CH}}_4}^{\′}=\frac{M_{{\mathrm{CH}}_4}\×{\mathrm{molefraction}}_{{\mathrm{CH}}_4}^{\′}}{\stackrel{\‾}{M}}\\ {\mathrm{massfraction}}_{\mathrm{CO}}^{\′}=\frac{M_{\mathrm{CO}}\×{\mathrm{molefraction}}_{\mathrm{CO}}^{\′}}{\stackrel{\‾}{M}}\end{array}$

Second step: according to engine operation condition, calculate the every circulation air inflow of every cylinder m by air-suction state visualizer _a, and the required standard C OG air fuel ratio of definite current working α, calculates the quality m of required standard C OG _cOG, its formula is as follows.

$m_{\mathrm{COG}}=\frac{m_a}{\mathrm{\α}}$

Meanwhile, according to the mass fraction of the each component of standard C OG with massfraction _cO, calculate H ₂, CH ₄quality with CO with m _cO, its formula is as follows.

$m_{H_2}=m_{\mathrm{COG}}\×{\mathrm{massfraction}}_{H_2}$

$m_{{\mathrm{CH}}_4}=m_{\mathrm{COG}}\×{\mathrm{massfraction}}_{C{H}_4}$

m _CO＝m _COG×massfraction _CO

The 3rd step: according to the mass fraction of each component in the actual COG above calculating with massfraction' _cO, calculate H ₂, CH ₄comparative parameter with CO with ω _cO, its formula is as follows.

${\mathrm{\ω}}_{H_2}=\frac{{\mathrm{massfraction}}_{H_2}^{\′}}{{\mathrm{massfraction}}_{H_2}}$

${\mathrm{\ω}}_{{\mathrm{CH}}_4}=\frac{{\mathrm{massfraction}}_{{\mathrm{CH}}_4}^{\′}}{{\mathrm{massfraction}}_{{\mathrm{CH}}_4}}$

${\mathrm{\ω}}_{\mathrm{CO}}=\frac{{\mathrm{massfraction}}_{\mathrm{CO}}^{\′}}{{\mathrm{massfraction}}_{\mathrm{CO}}}$

The 4th step: compared with parameter value, determine injection strategy according to high specific.

When when maximum, the emitted dose of current C OG is h ₂emitted dose be $m_{H_2}^{\′}=0,$ CH ₄emitted dose be $m_{{\mathrm{CH}}_4}^{\′}=m_{{\mathrm{CH}}_4}-m_{\mathrm{COG}}^{\′}\×{\mathrm{massfraction}}_{{\mathrm{CH}}_4}^{\′},$ The emitted dose of CO is m' _cO=m _cO-m' _cOG× massfraction' _cO.

When when maximum, the emitted dose of current C OG is h ₂emitted dose be $m_{H_2}^{\′}=m_{H_2}-m_{\mathrm{COG}}^{\′}\×{\mathrm{massfraction}}_{H_2}^{\′},$ CH ₄emitted dose be $m_{{\mathrm{CH}}_4}^{\′}=0,$ The emitted dose of CO is m' _cO=m _cO-m' _cOG× massfraction' _cO.

Work as ω _cOwhen maximum, the emitted dose of current C OG is h ₂emitted dose be $m_{H_2}^{\′}=m_{H_2}-m_{\mathrm{COG}}^{\′}\×{\mathrm{massfraction}}_{H_2}^{\′},$ CH ₄emitted dose be $m_{{\mathrm{CH}}_4}^{\′}=m_{{\mathrm{CH}}_4}-m_{\mathrm{COG}}^{\′}\×{\mathrm{massfraction}}_{{\mathrm{CH}}_4}^{\′},$ The emitted dose of CO is m' _cO=0.

Claims (1)

1. eliminate the method for COG component unstability on motor impact, it is characterized in that the method comprises the following steps:

The first step: choose the fixing COG of a kind of component as Standard Gases, its H ₂, CH ₄be respectively with the mass fraction of CO with massfraction _cO, method by experiment, respectively controls parameter to motor and demarcates, and realizes optimal control;

Second step: by being arranged on the H in COG gas tank ₂, CH ₄with CO sensor, measure the volume fraction of the above-mentioned three kinds of components of actual COG with molefraction' _cO, and measure temperature T, pressure p and the density p of current gas by temperature, pressure, gas densitometer;

The 3rd step: according to above-mentioned parameter, calculate the mass fraction of the each component of actual COG with massfraction' _cO, wherein R is ideal gas constant, represent H ₂molal weight, represent CH ₄molal weight, M _cOrepresent CO molal weight;

$\begin{array}{c}{\mathrm{massfraction}}_{H_2}^{\′}=\frac{M_{H_2}\×{\mathrm{molefraction}}_{H_2}^{\′}}{\stackrel{\‾}{M}}\\ {\mathrm{massfraction}}_{{\mathrm{CH}}_4}^{\′}=\frac{M_{{\mathrm{CH}}_4}\×{\mathrm{molefraction}}_{{\mathrm{CH}}_4}^{\′}}{\stackrel{\‾}{M}}\\ \begin{array}{cc}{\mathrm{massfraction}}_{\mathrm{CO}}^{\′}=\frac{M_{\mathrm{CO}}\×{\mathrm{molefaction}}_{\mathrm{CO}}^{\′}}{\stackrel{\‾}{M}}& \stackrel{\‾}{M}=\frac{\mathrm{\ρ}}{p}\mathrm{RT}\end{array}\end{array}$

According to the air inflow m of current working _a, air fuel ratio α, calculate the quality m of required standard C OG _cOG;

$m_{\mathrm{COG}}=\frac{m_a}{\mathrm{\α}}$

Meanwhile, according to the mass fraction of the each component of standard C OG with massfraction _cO, calculate H ₂, CH ₄quality with CO with m _cO, its formula is as follows;

$m_{H_2}=m_{\mathrm{COG}}\×{\mathrm{massfraction}}_{H_2}$

$m_{{\mathrm{CH}}_4}=m_{\mathrm{COG}}\×{\mathrm{massfraction}}_{C{H}_4}$

m _CO＝m _COG×massfraction _CO

According to each constituent mass mark of actual COG, determine actual COG, H ₂, CH ₄with the emitted dose of CO, realize the optimal control of COG engine combustion, specifically:

Calculate H ₂, CH ₄comparative parameter with CO with ω _cO:

${\mathrm{\ω}}_{H_2}=\frac{{\mathrm{massfraction}}_{H_2}^{\′}}{{\mathrm{massfraction}}_{H_2}},{\mathrm{\ω}}_{{\mathrm{CH}}_4}=\frac{{\mathrm{massfraction}}_{{\mathrm{CH}}_4}^{\′}}{{\mathrm{massfraction}}_{{\mathrm{CH}}_4}},{\mathrm{\ω}}_{\mathrm{CO}}=\frac{{\mathrm{massfraction}}_{\mathrm{CO}}^{\′}}{{\mathrm{massfraction}}_{\mathrm{CO}}}$

According to maximum comparative parameter, determine injection strategy;

When when maximum, the emitted dose of current C OG is h ₂emitted dose be $m_{H_2}^{\′}=0,$ CH ₄emitted dose be $m_{{\mathrm{CH}}_4}^{\′}=m_{{\mathrm{CH}}_4}-m_{\mathrm{COG}}^{\′}\×{\mathrm{massfraction}}_{{\mathrm{CH}}_4}^{\′},$ The emitted dose of CO is m' _cO=m _cO-m' _cOG× massfraction' _cO;

When when maximum, the emitted dose of current C OG is h ₂emitted dose be $m_{H_2}^{\′}=m_{H_2}-m_{\mathrm{COG}}^{\′}\×{\mathrm{massfraction}}_{H_2}^{\′},$ CH ₄emitted dose be $m_{{\mathrm{CH}}_4}^{\′}=0,$ The emitted dose of CO is m' _cO=m _cO-m' _cOG× massfraction' _cO;

Work as ω _cOwhen maximum, the emitted dose of current C OG is h ₂emitted dose be $m_{H_2}^{\′}=m_{H_2}-m_{\mathrm{COG}}^{\′}\×{\mathrm{massfraction}}_{H_2}^{\′},$ CH ₄emitted dose be $m_{{\mathrm{CH}}_4}^{\′}=m_{{\mathrm{CH}}_4}-m_{\mathrm{COG}}^{\′}\×{\mathrm{massfraction}}_{{\mathrm{CH}}_4}^{\′},$ The emitted dose of CO is m' _cO=0.