CN102062005B - Method for calculating air intake flow and air intake pressure of engine - Google Patents

Abstract

The invention discloses a method for calculating the air intake flow and air intake pressure of an engine. In the method, the rotating speed signal, the air intake temperature signal, the air intake pressure signal and the position parameters of a throttle valve of the engine are collected by utilizing an electronic control unit of the engine, and the air intake pressure, the mass flow of the air in the position of the throttle valve and the mass flow of the air flowing into a cylinder of the engine under various working conditions can be better accurately calculated by combining the volume data of an air intake manifold and the relative calibration scale of the electronic control unit.

Description

Method for calculating air inflow and air inflow pressure of engine

Technical Field

The invention relates to a method, in particular to a method for calculating air inflow and air inflow pressure of an engine.

Background

The electronic control fuel injection system of the engine determines the fuel injection quantity per cycle according to the air quantity sucked per cycle of the engine and the air-fuel ratio required under the working condition, and the measurement and calculation of the air quantity are the basis for realizing the air-fuel ratio control.

The intake model may present the air mass flow law for the engine combustion cycle at various operating conditions of idle, part load, lug, and lug for calculating the air mass flow at the throttle, the air mass flow out of the intake manifold, the intake manifold air pressure, and predicting the intake manifold pressure and the intake air amount for the base injection.

At present, the method for calculating the transient air intake of the engine is generally based on a charging and discharging method, wherein the whole air intake system is regarded as a container filled with single gas in a homogeneous state, and the air amount entering a cylinder is calculated by measuring engine parameters by using an ideal gas state equation and a mass conservation law. Meanwhile, the pressure of the intake manifold and the air inflow are calculated in real time through an air mass sensor signal in front of the throttle valve and through establishing a total flow Bernoulli equation of the compressible gas pipe.

The above calculation method neglects the complex environment of the intake system, so that the obtained pressure information of the intake manifold, the air mass flow information at the throttle valve and the air mass flow information entering the cylinder are not very accurate, which directly affects the calculation of the subsequent fuel injection quantity, and is further not beneficial to the engine in the optimal working state.

Disclosure of Invention

The invention provides a method for calculating air inflow and air inflow pressure of an engine aiming at the defects of the prior art.

The method for calculating the air inflow and the air inflow pressure of the engine comprises the steps of firstly, setting a crankshaft sensor for detecting the rotating speed information of the engine, a throttle position sensor for detecting the opening information of a throttle, an air inflow temperature sensor for detecting the air inflow temperature information, and an air inflow pressure sensor for detecting the ambient pressure and the air inflow pressure information, predicting the pressure ratio before and after the throttle according to the rotating speed of the engine and the opening of the throttle, setting the slope and intercept of the air inflow efficiency of a cylinder, setting the overflow area of the throttle according to the opening of the throttle, and setting the upstream pressure of the throttle according to the ambient pressure and the pressure drop parameter of an air filter;

and calculating the air mass flow at the current throttle valve, the air mass flow entering the cylinder and the intake pressure according to the engine speed information, the throttle opening information, the intake temperature information, the intake pressure information and the estimated pressure ratio before and after the throttle valve, the set inflation efficiency and intercept at the throttle valve, the slope and intercept of the inflation efficiency of the cylinder, the throttle valve flow area and the throttle valve upstream pressure.

In the method for calculating the air intake quantity and the air intake pressure of the engine, the ambient pressure is the pressure measured by the air intake pressure sensor before the engine is powered on but not started.

In the method for calculating the air intake quantity and the air intake pressure of the engine, the estimated pressure ratio PQ before and after the throttle valve^NComprises the following steps:

$P{Q}^N=\frac{P_{\mathrm{estim}}^N}{P_{\mathrm{thr}}}$

wherein,

predicted post-throttle pressure, P, for the Nth engine event cycle_thrIs throttle upstream pressure; and is <math> <mrow> <msubsup> <mi>P</mi> <mi>estim</mi> <mi>N</mi> </msubsup> <mo>=</mo> <msubsup> <mi>P</mi> <mi>im</mi> <mrow> <mi>N</mi> <mo>-</mo> <mn>1</mn> </mrow> </msubsup> <mo>+</mo> <mfrac> <mi>&Delta;t</mi> <mn>2</mn> </mfrac> <mo>&CenterDot;</mo> <mrow> <mo>(</mo> <msub> <mi>P</mi> <mi>im</mi> </msub> <mo>_</mo> <mi>DRV</mi> <msup> <mn>1</mn> <mrow> <mi>N</mi> <mo>-</mo> <mn>1</mn> </mrow> </msup> <mo>+</mo> <msub> <mi>P</mi> <mi>im</mi> </msub> <mo>_</mo> <mi>DRV</mi> <msup> <mn>1</mn> <mrow> <mi>N</mi> <mo>-</mo> <mn>2</mn> </mrow> </msup> <mo>)</mo> </mrow> </mrow> </math>

Wherein,

is the intake pressure, P, at a time preceding the interval of one engine event cycle_im_DRV1^N-1Is composed of

The first derivative of (a) is,

intake pressure, P, at a time preceding the interval of two engine event cycles_im_DRV1^N-2Is composed of

The pressure measured by the intake pressure sensor before the engine is powered on but not started is taken as the initial value of the intake pressure;

at is defined as the engine event period, i.e., the time required for 720 degrees of engine crankshaft rotation at the corresponding speed divided by the total number of engine cylinders.

In the method for calculating the air intake quantity and the air intake pressure of the engine, the air intake quantity and the air intake pressure are calculatedPressure of intake air

Comprises the following steps:

when PQ^NWhen the content is less than or equal to 0.99:

<math> <mrow> <msubsup> <mi>P</mi> <mi>im</mi> <mi>N</mi> </msubsup> <mo>=</mo> <mfrac> <mrow> <msubsup> <mi>P</mi> <mi>im</mi> <mrow> <mi>N</mi> <mo>-</mo> <mn>1</mn> </mrow> </msubsup> <mo>+</mo> <mfrac> <mi>&Delta;t</mi> <mn>2</mn> </mfrac> <mo>*</mo> <msub> <mi>P</mi> <mi>im</mi> </msub> <mo>_</mo> <mi>DRV</mi> <msup> <mn>1</mn> <mrow> <mi>N</mi> <mo>-</mo> <mn>1</mn> </mrow> </msup> <mo>+</mo> <mfrac> <mi>&Delta;t</mi> <mn>2</mn> </mfrac> <mi>MD</mi> <msub> <mi>L</mi> <mn>0</mn> </msub> <mo>*</mo> <mi>B</mi> </mrow> <mrow> <mn>1</mn> <mo>+</mo> <mfrac> <mi>&Delta;t</mi> <mn>2</mn> </mfrac> <mi>MD</mi> <msub> <mi>L</mi> <mn>0</mn> </msub> <mo>*</mo> <mi>A</mi> </mrow> </mfrac> </mrow> </math>

when 0.99 < PQ^NWhen the ratio is less than 1:

when PQ^NWhen the ratio is more than or equal to 1:

the 0.083hPa is the selected calculated gradient value;

wherein, the MDL₀For a given number of gas constants,

T_imis the current intake air temperature, V_imIs the intake manifold volume;

wherein χ ═ 1.4 is the adiabatic coefficient of air, R_air287 joules per kilogram, constant volume specific heat capacity for air;

MDL₁₁＝A_red·MDL₁wherein A is_redThe throttle valve flow area corresponding to the currently detected throttle valve opening information;

whereinAs the slope of the throttle charging efficiency,

is the slope of the cylinder charging efficiency;

wherein

Is the intercept of the charging efficiency of the throttle valve,

intercept for cylinder charge efficiency。

In the method for calculating the air intake quantity and the air intake pressure of the engine, the upstream pressure P of the throttle valve_thrEqual to ambient pressure minus the pressure drop that occurs as air passes through the air cleaner.

In the method for calculating the air inflow and the air inflow pressure of the engine, the mass flow of the air entering the cylinderComprises the following steps:

<math> <mrow> <msubsup> <mi>m</mi> <mi>cyl</mi> <mi>N</mi> </msubsup> <mo>=</mo> <msubsup> <mi>&eta;</mi> <mi>cyl</mi> <mi>slop</mi> </msubsup> <mo>&CenterDot;</mo> <msubsup> <mi>P</mi> <mi>im</mi> <mi>N</mi> </msubsup> <mo>-</mo> <msubsup> <mi>&eta;</mi> <mi>cyl</mi> <mi>ofs</mi> </msubsup> </mrow> </math>

wherein,

as the slope of the current cylinder charging efficiency,

is the intercept of the current cylinder charge efficiency.

Is the current intake pressure.

In the method for calculating the air inflow and the air inflow pressure of the engine, the air mass flow at the throttle valve

Comprises the following steps:

when PQ^NWhen the carbon content is more than 0.99,

when PQ^NWhen the content is less than or equal to 0.99, <math> <mrow> <msubsup> <mi>m</mi> <mi>thr</mi> <mi>N</mi> </msubsup> <mo>=</mo> <mi>MD</mi> <msub> <mi>L</mi> <mn>11</mn> </msub> <mo>*</mo> <mrow> <mo>(</mo> <msubsup> <mi>&eta;</mi> <mi>thr</mi> <mi>ofs</mi> </msubsup> <mo>*</mo> <msub> <mi>P</mi> <mi>thr</mi> </msub> <mo>-</mo> <msubsup> <mi>&eta;</mi> <mi>thr</mi> <mi>slop</mi> </msubsup> <mo>*</mo> <msubsup> <mi>P</mi> <mi>im</mi> <mi>N</mi> </msubsup> <mo>)</mo> </mrow> <mo>.</mo> </mrow> </math>

according to the method for calculating the air inflow and the air inflow pressure of the engine, the pressure information of the air inlet manifold, the air mass flow information at the air throttle and the air mass flow information entering the cylinder are obtained in real time according to the environment where the current air inlet system is located, so that the subsequent oil injection amount can be calculated accurately, and the engine is guaranteed to be always in the optimal working state.

Detailed Description

The present invention is described in further detail below to enable those skilled in the art to practice the invention with reference to the description.

When the method for calculating the air inflow and the air inflow pressure of the engine is particularly applied to an Electronic Control Unit (ECU) of the engine, the rotating speed of the engine is defined as a variable N and the ambient pressure P_ampIs defined as variable AMP, throttle upstream pressure P_thrDefined as the variable PRS UP THR,the throttle opening signal is defined as the variable TPS, the throttle flow area A_redDefined as a variable AR _ RED, a pre-throttle pressure ratio PQ defined as a variable PQ, a slope of throttle charging efficiency

Defined as the variable MAF _ FAC _ SLOP, intercept of throttle charging efficiency

Is defined as the variable MAF _ FAC _ OFS, mass air flow at throttle m_thrIs defined as the variable MAF _ THR, intake manifold volume V_imDefined as the variable VOL _ IM, intake pressure P_imSlope of cylinder charge efficiency defined as variable MAP

The wave is defined as the variable EFF _ VOL _ SLOP, the intercept of the cylinder charge efficiency

Defined as variable EFF _ VOL _ OFS, mass air flow into the cylinder m_cylIs defined as MAF _ CYL, intake air temperature T_imDefined as the variable TIA,.

When air flows through the air filter, corresponding pressure drop is caused according to different air flow rates, the pressure drop is a calibratable quantity, and pressure drop parameters AMP _ DEC of the air filter corresponding to different air inflow rates are stored in a calibration table IP _ AMP _ DEC.

The throttle valve flow area AR _ RED is a calibratable quantity, and calibration values corresponding to different throttle valve opening degrees are stored in a calibration table IP _ AR _ RED _ THR _ TPS.

The slope of the throttle charging efficiency MAF _ FAC _ SLOP is a calibratable amount, and a calibration for different pre-throttle and post-throttle pressure ratios PQ is stored in a calibration table IP _ MAF _ FAC _ SLOP _ PQ.

The intercept of the throttle charging efficiency, MAF _ FAC _ OFS, is a calibratable quantity, and is stored in a calibration table, IP _ MAF _ FAC _ OFS _ PQ, relative to calibration values of different pre-throttle and post-throttle pressure ratios, PQ.

The calibration tables IP _ MAF _ FAC _ SLOP _ PQ and IP _ MAF _ FAC _ OFS _ PQ use the same calibration break points.

The slope of the cylinder charge efficiency, EFF _ VOL _ SLOP, is a calibratable quantity, and is stored in a calibration table IP _ EFF _ VOL _ SLOP _ N relative to calibration values at different engine speeds N.

The intercept of the cylinder charge efficiency, EFF _ VOL _ OFS, is a calibratable quantity, and is stored in a calibration table IP _ EFF _ VOL _ OFS _ N relative to calibration values at different engine speeds N.

The calibration tables IP _ EFF _ VOL _ slope _ N and IP _ EFF _ VOL _ OFS _ N use the same calibration break point.

After the calibration of an engine is completed, an engine electronic control unit adopting the method can calculate the MASs air flow MAF _ THR at the throttle valve, the MASs air flow MAF _ CYL entering the cylinder and the intake air pressure MAP under different working conditions according to an engine rotating speed signal N measured by a crankshaft sensor, a throttle opening signal TPS measured by a throttle opening sensor, an intake air temperature signal TIA measured by an intake air temperature sensor and a pressure signal MAP _ MAS measured by an intake air pressure sensor. The calculation steps are as follows:

step 1, after the engine is powered on, the variable AMP is assigned with the pressure signal MAP _ MES collected by the intake pressure sensor as the ambient pressure, and this value is also used as the initial value of the intake pressure.

And 2, starting after the engine is started, interpolating a calibration table IP _ AMP _ DEC by an engine electronic control unit according to a preset frequency, calculating a throttle upstream pressure PRS _ UP _ THR (PRS _ UP _ THR is AMP-AMP _ DEC), estimating a throttle pressure after the throttle according to a rotating speed signal N acquired by a crankshaft sensor and an initial intake pressure value, calculating a throttle front-back pressure ratio PQ, and interpolating the calibration table IP _ AR _ RED _ THR _ TPS according to a throttle opening signal TPS to obtain a throttle overflow area AR _ RED.

Step 4, interpolating a calibration table IP _ MAF _ FAC _ SLOP _ PQ and an IP _ MAF _ FAC _ OFS _ PQ by an engine electronic control unit according to the pressure ratio PQ before and after the throttle valve to obtain a slope MAF _ FAC _ SLOP and an intercept MAF _ FAC _ OFS of the throttle valve charging efficiency;

step 5, the engine electronic control unit interpolates the calibration tables IP _ EFF _ VOL _ SLOP _ N and IP _ EFF _ VOL _ OFS _ N according to the engine rotating speed N to obtain the slope EFF _ VOL _ SLOP and the intercept EFF _ VOL _ OFS of the cylinder inflation efficiency;

step 6, an engine electronic control unit calculates an intake pressure MAP according to the engine speed N, the intake manifold volume VOL _ IM, the throttle valve overflow area AR _ RED, the intake air temperature TIA collected by an intake air temperature sensor, the slope MAF _ FAC _ SLOP and the intercept MAF _ FAC _ OFS of the throttle valve charging efficiency, and the slope EFF _ VOL _ SLOP and the intercept EFF _ VOL _ OFS of the cylinder charging efficiency;

step 7, an engine electronic control unit calculates the mass air flow MAF _ CYL entering the cylinder according to the intake pressure MAP, the slope EFF _ VOL _ SLOP and the intercept EFF _ VOL _ OFS of the cylinder charging efficiency;

in step 8, the engine electronic control unit calculates the mass air flow MAF _ THR at the inlet and outlet throttle according to the inlet air temperature TIA, the throttle valve flow area AR _ RED, the throttle valve upstream pressure PRS _ UP _ THR, the inlet air pressure MAP, the slope MAF _ FAC _ SLOP of the throttle valve charging efficiency and the intercept MAF _ FAC _ OFS.

In the method for calculating the air inflow and the air inflow pressure of the engine, the air inflow pressure, the air mass flow entering the cylinder and the air mass flow information at the throttle valve can be expressed by the following formulas:

according to the principle of conservation of the air inflow in the air intake manifold, an ideal gas equation is established as follows:

<math> <mrow> <mfrac> <mo>&PartialD;</mo> <msub> <mo>&PartialD;</mo> <mi>t</mi> </msub> </mfrac> <mfrac> <mrow> <msub> <mi>P</mi> <mi>im</mi> </msub> <msub> <mi>V</mi> <mi>im</mi> </msub> </mrow> <mrow> <msub> <mi>R</mi> <mi>air</mi> </msub> <msub> <mi>T</mi> <mi>im</mi> </msub> </mrow> </mfrac> <mo>=</mo> <msub> <mi>m</mi> <mi>thr</mi> </msub> <mo>-</mo> <msub> <mi>m</mi> <mi>out</mi> </msub> </mrow> </math> equation 1

Wherein the air flow at the throttle valve is m_thrI.e. mass air flow into the intake manifold, air flow out of the intake manifold m_cylI.e. the mass flow of air into the cylinder, T_imIs the intake air temperature.

Intake manifold pressure was modeled as:

<math> <mrow> <mfrac> <mo>&PartialD;</mo> <msub> <mo>&PartialD;</mo> <mi>t</mi> </msub> </mfrac> <msub> <mi>P</mi> <mi>im</mi> </msub> <mo>=</mo> <mfrac> <mrow> <msub> <mi>R</mi> <mi>air</mi> </msub> <msub> <mi>T</mi> <mi>im</mi> </msub> </mrow> <msub> <mi>V</mi> <mi>im</mi> </msub> </mfrac> <mrow> <mo>(</mo> <msub> <mi>m</mi> <mi>thr</mi> </msub> <mo>-</mo> <msub> <mi>m</mi> <mtext>cyl</mtext> </msub> <mo>)</mo> </mrow> </mrow> </math> equation 2

In formula 2, R_air287 joules per kilogram, air constant volume specific heat capacity, conveniently expressed by the following formula, will

Abbreviated as P_im_DRV1。

To calculate the intake manifold pressure, it is necessary to linearize the throttle air flow characteristic and determine the slope of its linear equation

And interceptTo realize the linear equation, the pressure ratio PQ before and after the throttle valve must be estimated:

$P{Q}^N=\frac{P_{\mathrm{estim}}^N}{P_{\mathrm{thr}}}$ equation 3

Wherein the throttle back pressure

The estimation formula of (c) is:

<math> <mrow> <msubsup> <mi>P</mi> <mi>estim</mi> <mi>N</mi> </msubsup> <mo>=</mo> <msubsup> <mi>P</mi> <mi>im</mi> <mrow> <mi>N</mi> <mo>-</mo> <mn>1</mn> </mrow> </msubsup> <mo>+</mo> <mfrac> <mi>&Delta;t</mi> <mn>2</mn> </mfrac> <mo>&CenterDot;</mo> <mrow> <mo>(</mo> <msub> <mi>P</mi> <mi>im</mi> </msub> <mo>_</mo> <mi>DRV</mi> <msup> <mn>1</mn> <mrow> <mi>N</mi> <mo>-</mo> <mn>1</mn> </mrow> </msup> <mo>+</mo> <msub> <mi>P</mi> <mi>im</mi> </msub> <mo>_</mo> <mi>DRV</mi> <msup> <mn>1</mn> <mrow> <mi>N</mi> <mo>-</mo> <mn>2</mn> </mrow> </msup> <mo>)</mo> </mrow> </mrow> </math> equation 4

Where Δ t is the engine event period, i.e., the time required for 720 degrees of engine crankshaft rotation at the corresponding speed divided by the total number of engine cylinders.

For the estimated post-throttle pressure for the nth engine event cycle,

is the intake pressure, P, at a time preceding the interval of one engine event cycle_im_DRV1^N-1Is composed of

The first derivative of (a) is,

intake pressure, P, at a time preceding the interval of two engine event cycles_im_DRV1^N-2Is composed of

The pressure measured by the intake pressure sensor before the engine is powered up but not started is taken as the initial value of the intake pressure.

If estimated

Then get

Here 0.083hPa is a calculated gradient value taken empirically.

With respect to the relationship between the air flow rate at the throttle valve and the intake air temperature, the following 2 intermediate variables are setMDL₁And MDL₁₁Respectively is as follows:

wherein χ ═ 1.4 is the adiabatic coefficient of air, R_air287 joules per kilogram, constant specific heat capacity for air, T_imIs the current intake air temperature;

MDL₁₁＝A_red·MDL₁wherein A is_redThe throttle valve flow area corresponding to the currently detected throttle valve opening information;

for the convenience of formula expression, 2 abbreviations a and B are set, which respectively represent:

whereinAs the slope of the current throttle charging efficiency,

the slope of the current cylinder charging efficiency;

wherein

Is the intercept of the current throttle charging efficiency,

intercept, P, of current cylinder charging efficiency_thrIs the throttle upstream pressure.

When PQ^NWhen the content is less than or equal to 0.99:

<math> <mrow> <msubsup> <mi>P</mi> <mi>im</mi> <mi>N</mi> </msubsup> <mo>=</mo> <mfrac> <mrow> <msubsup> <mi>P</mi> <mi>im</mi> <mrow> <mi>N</mi> <mo>-</mo> <mn>1</mn> </mrow> </msubsup> <mo>+</mo> <mfrac> <mi>&Delta;t</mi> <mn>2</mn> </mfrac> <mo>*</mo> <msub> <mi>P</mi> <mi>im</mi> </msub> <mo>_</mo> <mi>DRV</mi> <msup> <mn>1</mn> <mrow> <mi>N</mi> <mo>-</mo> <mn>1</mn> </mrow> </msup> <mo>+</mo> <mfrac> <mi>&Delta;t</mi> <mn>2</mn> </mfrac> <mi>MD</mi> <msub> <mi>L</mi> <mn>0</mn> </msub> <mo>*</mo> <mi>B</mi> </mrow> <mrow> <mn>1</mn> <mo>+</mo> <mfrac> <mi>&Delta;t</mi> <mn>2</mn> </mfrac> <mi>MD</mi> <msub> <mi>L</mi> <mn>0</mn> </msub> <mo>*</mo> <mi>A</mi> </mrow> </mfrac> </mrow> </math> equation 5

Wherein the MDL₀For a given number of gas constants,

V_imis the intake manifold volume.

When 0.99 < PQ^NWhen the ratio is less than 1:

$P_{\mathrm{im}}^N=\frac{B}{A}$ equation 6

When PQ^NWhen the ratio is more than or equal to 1:

$P_{\mathrm{im}}^N=P_{\mathrm{thr}}-0.083\mathrm{hPa}$ equation 7

The mass flow of air entering the cylinder is:

<math> <mrow> <msubsup> <mi>m</mi> <mi>cyl</mi> <mi>N</mi> </msubsup> <mo>=</mo> <msubsup> <mi>&eta;</mi> <mi>cyl</mi> <mi>slop</mi> </msubsup> <mo>&CenterDot;</mo> <msubsup> <mi>P</mi> <mi>im</mi> <mi>N</mi> </msubsup> <mo>-</mo> <msubsup> <mi>&eta;</mi> <mi>cyl</mi> <mi>ofs</mi> </msubsup> </mrow> </math> equation 8

Mass flow m of air entering the throttle_thrComprises the following steps:

when PQ^NAt > 0.99:

$m_{\mathrm{thr}}^N=m_{\mathrm{cyl}}^N$ equation 9;

when PQ^NWhen the content is less than or equal to 0.99:

<math> <mrow> <msubsup> <mi>m</mi> <mi>thr</mi> <mi>N</mi> </msubsup> <mo>=</mo> <mi>MD</mi> <msub> <mi>L</mi> <mn>11</mn> </msub> <mo>*</mo> <mrow> <mo>(</mo> <msubsup> <mi>&eta;</mi> <mi>thr</mi> <mi>ofs</mi> </msubsup> <mo>*</mo> <msub> <mi>P</mi> <mi>thr</mi> </msub> <mo>-</mo> <msubsup> <mi>&eta;</mi> <mi>thr</mi> <mi>slop</mi> </msubsup> <mo>*</mo> <msubsup> <mi>P</mi> <mi>im</mi> <mi>N</mi> </msubsup> <mo>)</mo> </mrow> </mrow> </math> equation 10

The method for calculating the air inflow and the air inflow pressure of the engine is simple to realize, accurate in result, easy to realize and integrate through programming based on hardware such as a sensor, a single chip microcomputer and the like, and has good application and development prospects under the great trend of rapid development of domestic automobile technology.

While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.

Claims (3)

1. A method for calculating air inflow and air inflow pressure of an engine is characterized in that a crankshaft sensor for detecting engine rotating speed information, a throttle valve position sensor for detecting throttle valve opening information, an air inflow temperature sensor for detecting air inflow temperature information and an air inflow pressure sensor for detecting ambient pressure and air inflow pressure information are arranged, pressure ratios before and after a throttle valve are estimated according to the engine rotating speed and the throttle valve opening, the slope and intercept of throttle valve inflation efficiency and the slope and intercept of cylinder inflation efficiency are set, the throttle valve overflowing area is set according to the throttle valve opening, and the upstream pressure of the throttle valve is set according to the ambient pressure and the pressure drop parameter of an air filter;

calculating the air mass flow at the current throttle valve, the air mass flow entering the cylinder and the intake pressure according to the engine speed information, the throttle opening information, the intake temperature information, the intake pressure information and the estimated pressure ratio before and after the throttle valve, the set inflation efficiency and intercept at the throttle valve, the slope and intercept of the inflation efficiency of the cylinder, the throttle valve flow area and the throttle valve upstream pressure;

the estimated pressure ratio PQ before and after the throttle valve^NComprises the following steps:

${\mathrm{PQ}}^N=\frac{P_{\mathrm{estim}}^N}{P_{\mathrm{thr}}}$

wherein,

predicted post-throttle pressure, P, for the Nth engine event cycle_thrIs throttle upstream pressure, and <math> <mrow> <msubsup> <mi>P</mi> <mi>estim</mi> <mi>N</mi> </msubsup> <mo>=</mo> <msubsup> <mi>P</mi> <mi>im</mi> <mrow> <mi>N</mi> <mo>-</mo> <mn>1</mn> </mrow> </msubsup> <mo>+</mo> <mfrac> <mi>&Delta;t</mi> <mn>2</mn> </mfrac> <mo>&CenterDot;</mo> <mrow> <mo>(</mo> <msub> <mi>P</mi> <mrow> <mi>im</mi> <mo>_</mo> </mrow> </msub> <msup> <mrow> <mi>DRV</mi> <mn>1</mn> </mrow> <mrow> <mi>N</mi> <mo>-</mo> <mn>1</mn> </mrow> </msup> <mo>+</mo> <msub> <mi>P</mi> <mrow> <mi>im</mi> <mo>_</mo> </mrow> </msub> <msup> <mrow> <mi>DRV</mi> <mn>1</mn> </mrow> <mrow> <mi>N</mi> <mo>-</mo> <mn>2</mn> </mrow> </msup> <mo>)</mo> </mrow> </mrow> </math>

wherein,

is the intake pressure, P, at a time preceding the interval of one engine event cycle_im-DRV1^N-1Is composed of

The first derivative of (a) is,

intake pressure, P, at a time preceding the interval of two engine event cycles_im-DRV1^N-2Is composed ofThe pressure measured by the intake pressure sensor before the engine is powered on but not started is taken as the initial value of the intake pressure;

Δ t is a defined engine event period, i.e., the time required for the engine crankshaft to rotate 720 degrees at the corresponding speed divided by the total number of engine cylinders;

the inlet pressure

Comprises the following steps:

when PQ^NWhen the content is less than or equal to 0.99:

<math> <mrow> <msubsup> <mi>P</mi> <mi>im</mi> <mi>N</mi> </msubsup> <mo>=</mo> <mfrac> <mrow> <msubsup> <mi>P</mi> <mi>im</mi> <mrow> <mi>N</mi> <mo>-</mo> <mn>1</mn> </mrow> </msubsup> <mo>+</mo> <mfrac> <mi>&Delta;t</mi> <mn>2</mn> </mfrac> <mo>*</mo> <msub> <mi>P</mi> <mrow> <mi>im</mi> <mo>_</mo> </mrow> </msub> <msup> <mrow> <mi>DRV</mi> <mn>1</mn> </mrow> <mrow> <mi>N</mi> <mo>-</mo> <mn>1</mn> </mrow> </msup> <mo>+</mo> <mfrac> <mi>&Delta;t</mi> <mn>2</mn> </mfrac> <msub> <mi>MDL</mi> <mn>0</mn> </msub> <mo>*</mo> <mi>B</mi> </mrow> <mrow> <mn>1</mn> <mo>+</mo> <mfrac> <mi>&Delta;t</mi> <mn>2</mn> </mfrac> <msub> <mi>MDL</mi> <mn>0</mn> </msub> <mo>*</mo> <mi>A</mi> </mrow> </mfrac> </mrow> </math>

when 0.99 < PQ^NWhen the ratio is less than 1:

when PQ^NWhen the ratio is more than or equal to 1:

the 0.083hPa is selected calculation gradient value, wherein the MDL₀For a given number of gas constants,T_imis the current intake air temperature, V_imIntake manifold volume;

<math> <mrow> <msub> <mi>MDL</mi> <mn>1</mn> </msub> <mo>=</mo> <msqrt> <mfrac> <mrow> <mn>2</mn> <mo>&CenterDot;</mo> <mi>&chi;</mi> </mrow> <mrow> <mi>&chi;</mi> <mo>-</mo> <mn>1</mn> </mrow> </mfrac> <mo>&CenterDot;</mo> <mfrac> <mn>1</mn> <mrow> <msub> <mi>R</mi> <mi>air</mi> </msub> <mo>&CenterDot;</mo> <msub> <mi>T</mi> <mi>im</mi> </msub> </mrow> </mfrac> </msqrt> <mo>,</mo> </mrow> </math> where x is 1.4, R is the adiabatic coefficient of air_air=287 joules per kilogram per unit of time;

MDL₁₁＝A_red.MDL₁wherein A is_redThe throttle valve flow area corresponding to the currently detected throttle valve opening information;

wherein

As the slope of the throttle charging efficiency,

is the slope of the cylinder charging efficiency;

wherein

Is the intercept of the charging efficiency of the throttle valve,an intercept that is the cylinder charging efficiency;

the mass flow of air into the cylinder

Comprises the following steps:

<math> <mrow> <msubsup> <mi>m</mi> <mi>cyl</mi> <mi>N</mi> </msubsup> <mo>=</mo> <msubsup> <mi>&eta;</mi> <mi>cyl</mi> <mi>slop</mi> </msubsup> <mo>&CenterDot;</mo> <msubsup> <mi>P</mi> <mi>im</mi> <mi>N</mi> </msubsup> <mo>-</mo> <msubsup> <mi>&eta;</mi> <mi>cyl</mi> <mi>ofs</mi> </msubsup> </mrow> </math>

wherein,

as the slope of the current cylinder charging efficiency,

the intercept of the current cylinder charge efficiency is,is the current intake pressure;

mass air flow at the throttle

Comprises the following steps:

when PQ^NWhen the carbon content is more than 0.99,

when PQ^NWhen the content is less than or equal to 0.99, <math> <mrow> <msubsup> <mi>m</mi> <mi>thr</mi> <mi>N</mi> </msubsup> <mo>=</mo> <msub> <mi>MDL</mi> <mn>11</mn> </msub> <mo>*</mo> <mrow> <mo>(</mo> <msubsup> <mi>&eta;</mi> <mi>thr</mi> <mi>ofs</mi> </msubsup> <mo>*</mo> <msub> <mi>P</mi> <mi>thr</mi> </msub> <mo>-</mo> <msubsup> <mi>&eta;</mi> <mi>thr</mi> <mi>slop</mi> </msubsup> <mo>*</mo> <msubsup> <mi>P</mi> <mi>im</mi> <mi>N</mi> </msubsup> <mo>)</mo> </mrow> <mo>.</mo> </mrow> </math>

2. the method of calculating engine air intake and intake pressures of claim 1 wherein ambient pressure is the pressure measured by the intake pressure sensor before the engine is powered up but not started.

3. The method of calculating the intake air amount and the intake air pressure of the engine according to claim 1, wherein the throttle upstream pressure P_thrEqual to ambient pressure minus the pressure drop that occurs as air passes through the air cleaner.