CN104405509A - Online combustible gas mixing method of gas engine - Google Patents
Online combustible gas mixing method of gas engine Download PDFInfo
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- CN104405509A CN104405509A CN201410563059.1A CN201410563059A CN104405509A CN 104405509 A CN104405509 A CN 104405509A CN 201410563059 A CN201410563059 A CN 201410563059A CN 104405509 A CN104405509 A CN 104405509A
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- 238000002156 mixing Methods 0.000 title claims abstract description 19
- 238000000034 method Methods 0.000 title claims abstract description 18
- 239000007789 gas Substances 0.000 claims abstract description 71
- 238000002347 injection Methods 0.000 claims abstract description 47
- 239000007924 injection Substances 0.000 claims abstract description 47
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 5
- 239000001301 oxygen Substances 0.000 claims abstract description 5
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 5
- 239000000446 fuel Substances 0.000 claims description 16
- 239000002737 fuel gas Substances 0.000 description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000003502 gasoline Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Abstract
The invention provides an online combustible gas mixing method of a gas engine. If mixed gas consists of m combustible gases, m groups of injection rails are installed at a position close to a gas valve on an engine gas inlet manifold and respectively correspond to gas tanks of m combustible gases. An engine ECU determines gas injection pulse width through a map searching method according to engine working conditions, corrects the gas injection pulse width and controls the injection rails to inject a proper amount of combustible gas. A control unit acquires the gas injection pulse width in the map of the engine ECU under the current working condition, calculates the current gas injection pulse width of the corresponding combustible gas and corrects the gas injection pulse width according to measured temperature and pressure. A linear oxygen sensor is used for measuring excess air coefficient, and a calibration system is used for calibrating the gas injection pulse width in the map under the current working condition to enable the excess air coefficient to be 1, such that the combustible gas in the engine can be fully combusted. The invention provides an online mixing system which is safe and convenient, and the concentration of components can be flexibly changed by modifying the control unit.
Description
Technical Field
The invention belongs to the technical field of engine engineering, and relates to a method for mixing combustible gas on line by a gas engine. The method is suitable for the gas engine modified by the gasoline engine at present, when fuel is formed by mixing a plurality of combustible gases, the combustible gases can be mixed on line according to the proportion, the engine can run under the state of the optimal air-fuel ratio by calibrating the jet pulse width MAP in the ECU through a calibration system, and the various combustible gases can be mixed according to different proportions by modifying the program of a control unit.
Background
With the rapid development of the automobile industry, the huge energy consumption threatens the national energy supply safety, and simultaneously, the discharged large amount of tail gas also directly threatens the ecological environment and human health. The alternative fuel for cleaning vehicles has become an important subject of research in various countries, wherein alcohol fuels and gas fuels are the most widely used alternative fuels, but compared with alcohol fuels, gas fuels have great advantages in many aspects such as resources, economy, emission, safety and the like, and are the first choice alternative fuels for automobiles at present.
Currently, scientists have access to multiple single component fuel gases (e.g., CH)4、H2Etc.) have been studied for use in engines, they have more or less problems in terms of emissions, knocking, dynamics, etc. due to the influence of their respective physicochemical and combustion characteristics, and gaseous fuels in which various combustible gases are mixed have gradually come into the field of vision of people who can burn themThe characteristics are complemented, abnormal combustion is eliminated, and the running and emission requirements of the engine are met. Therefore, a set of mixed gas supply system is required to be designed, so that the mixing of multiple combustible gases in proportion is realized, the stability of components is ensured, and the engine can work in the best state.
Currently, the common gas mixture supply has two modes of constant pressure proportioning and online mixing. The constant-pressure proportioning adopts external mixing, and the mixed mixture is used as a single fuel to be supplied to an engine, but the air distribution needs to be carried out under high pressure, so that the danger is high, the difficulty is high, the component concentration is fixed, and the large waste can be generated. The on-line mixing adopts built-in mixing, which can overcome the disadvantages, but the current commonly used on-line mixing system needs to adopt a high-precision flowmeter, and the system is complex and has overhigh cost.
Disclosure of Invention
The invention aims to provide a method for mixing combustible gas on line for a gas engine. If the mixed gas consists of m kinds of combustible gas, m groups of injection rails are arranged at the position, close to the air valve, of an engine intake manifold and respectively correspond to the gas tanks of the m kinds of combustible gas. Wherein one group of injection rails is controlled by an engine ECU, and the other m-1 groups of injection rails are controlled by m-1 control units. And the engine ECU determines the jet pulse width by a method of searching an MAP according to the working condition of the engine, corrects the jet pulse width according to the temperature and the pressure measured at the corresponding pressure reducing valve and controls the injection rail to inject a proper amount of fuel gas. The control unit collects the jet pulse width in the MAP of the engine ECU under the current working condition, calculates the jet pulse width of the current corresponding fuel gas according to the volume fraction of the fuel gas corresponding to the jet pulse width and corrects the jet pulse width according to the temperature and the pressure measured at the corresponding pressure reducing valve. And measuring an excess air coefficient by using a linear oxygen sensor (UEGO), and calibrating the air injection pulse width in the MAP under the current working condition by using a calibration system to ensure that the excess air coefficient is 1, so that the fuel gas in the engine can be fully combusted.
The specific technical scheme of the invention is as follows:
the first step is as follows: m groups of injection rails are arranged at the position, close to an air valve, of an engine intake manifold and respectively correspond to m gas components of the mixed gas, and the volume fraction of the gas 1 is vf1Volume fraction of gas 2 is vf2… …, volume fraction of gas m is vfmThen vf1+vf2+...+vfmThe injection rail 1 is controlled by an engine ECU, and the rest m-1 groups of injection rails are respectively controlled by m-1 control units. In addition, pressure reducing valves with temperature and pressure sensors, pressure reducing valve 1, pressure reducing valves 2, … …, and pressure reducing valve m, respectively, are installed between the injection rail and the engine ECU or the control unit.
The second step is that: according to throttle opening of engineThe engine speed n, the initial jet pulse width T of the engine is determined by searching the MAP, and the temperature T measured by the pressure reducing valve 1 is used as the basis1Pressure p1Correcting the jet pulse width t, wherein the corrected jet pulse width is t1Thereby controlling the air injection of the injection rail 1.
The third step: the control unit 1 acquires an initial jet pulse width t of an engine ECU (electronic control Unit), and calculates the initial jet pulse width t 'of the injection rail 2 according to the volume fractions of gas 1 and gas 2'2：
At the same time, according to the temperature T measured by the pressure reducing valve 22Pressure p2Initial jet pulsewidth t 'to jet rail 2'2Make a correctionCorrected jet pulse width t2。
Respectively calculating and correcting to obtain the jet pulse width t from the jet rail 3 to the jet rail m by using the same method3、t4、...、tm。
The fourth step: the excess air factor λ is measured using a linear oxygen sensor and the theoretical ECU initial jet pulsewidth t ″ is calculated when λ is 1:
t″＝t×λ
and correcting the initial jet pulse width by using the incremental PID controller according to the difference value between the initial jet pulse width t and the calculated theoretical jet pulse width t' under the condition of meeting a certain condition, so that the engine operates in the state of the optimal air-fuel ratio.
The invention has the beneficial effects that:
(1) the invention belongs to an on-line mixing system, is safe and convenient, can flexibly change the component concentration by modifying the program of a control unit, and meets the requirements of scientific research and use.
(2) The invention does not need to use high-precision instruments and equipment, and has high economical efficiency.
(3) The invention utilizes a calibration system and adopts an incremental PID controller to correct the jet pulse width in the MAP, thereby ensuring that the engine always runs under the state of the optimal air-fuel ratio.
Drawings
Fig. 1 is a gas supply control block diagram of a gas engine according to the present invention.
FIG. 2 is a flow chart for calibrating an ECU jet pulsewidth MAP MAP for a method for on-line blending of combustible gases in a gas engine.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Fig. 1 is a gas supply control block diagram of a gas engine according to the present invention. The gas engine is modified on the basis of a gasoline engine, m groups of gas injection rails are added at the position, close to a valve, of an air inlet manifold and respectively correspond to m gas components of mixed gas, one group of gas injection rails is controlled by an engine ECU, the other gas injection rails are controlled by a control unit, and the control unit calculates the gas injection pulse width of the corresponding gas according to the volume fraction of each gas component on the basis of the gas injection pulse width obtained by searching MAP by the engine ECU, so that the mixing of various gases according to a certain proportion is realized. In addition, the accuracy of the mixing proportion is ensured by correcting the air injection pulse width through parameters such as temperature and pressure at the pressure reducing valve. The engine can be operated in the state of the optimal air-fuel ratio all the time by an incremental PID controller and by utilizing a calibration system to calibrate an air injection pulse width MAP in the ECU.
The method comprises the following specific steps:
the first step is as follows: m groups of injection rails are arranged at the position, close to an air valve, of an engine intake manifold and respectively correspond to m fuel gas components (the volume fraction of fuel gas 1 is vf)1Volume fraction of gas 2 is vf2… …, volume fraction of gas m is vfm，vf1+vf2+...+vfm1), namely the injection rail 1 corresponds to the fuel gas 1, the injection rail 2 corresponds to the fuel gas 2 and … …, and the injection rail m corresponds to the fuel gas m, wherein the injection rail 1 is controlled by an engine ECU, and the other m-1 groups of injection rails are respectively controlled by m-1 control units. In addition, pressure reducing valves with temperature and pressure sensors, pressure reducing valve 1, pressure reducing valves 2, … …, and pressure reducing valve m, respectively, need to be installed between the injection rail and the engine ECU or the control unit.
The second step is that: according to throttle opening of engineThe initial jet pulse width T of the engine is determined by searching the MAP method according to the working condition parameters such as the engine speed n and the like, and the temperature T measured by the pressure reducing valve 1 is used1Pressure p1Correcting the jet pulse width t, wherein the corrected jet pulse width is t1Thereby controlling the air injection of the injection rail 1.
The third step: the control unit 1 acquires an initial jet pulse width t of an engine ECU (electronic control Unit), and calculates the initial jet pulse width t 'of the injection rail 2 according to the volume fractions of gas 1 and gas 2'2：
At the same time, according to the temperature T measured by the pressure reducing valve 22Pressure p2Initial jet pulsewidth t 'to jet rail 2'2Corrected to have a jet pulse width t2。
Respectively calculating and correcting to obtain the jet pulse width t from the jet rail 3 to the jet rail m by using the same method3、t4、...、tm。
The fourth step: the excess air ratio λ is measured using a linear oxygen sensor (UEGO), and the theoretical ECU initial jet pulsewidth t' is calculated when λ is 1:
t″＝t×λ
and correcting the initial jet pulse width by using the incremental PID controller according to the difference value between the initial jet pulse width t and the calculated theoretical jet pulse width t' under the condition of meeting a certain condition, so that the engine operates in an optimal air-fuel ratio state (lambda is 1).
FIG. 2 is a flow chart for calibrating an ECU jet pulsewidth MAP MAP for a method for on-line blending of combustible gases in a gas engine.
The method comprises the following specific steps:
the first step is as follows: and calculating the theoretically required air injection pulse width t' (n) when the excess air coefficient lambda is to be equal to 1 according to the air injection pulse width t (n) of the current working condition read from the MAP and the excess air coefficient lambda (n) read from the UEGO.
t″(n)＝t(n)×λ(n)
The second step is that: the difference t between the current theoretical jet pulse width t' (n) and the actual jet pulse width t (n)D(n)。
tD(n)＝t″(n)-t(n)
The third step: will tDAnd (n) as an input parameter, calculating the air injection pulse width correction value delta t (n) by an incremental PID controller. The incremental PID control can ensure the control precision and improve the robustness of the system, and the algorithm is shown as follows.
Δt(n)＝a0tD(n)-a1tD(n-1)+a2tD(n-2)
Wherein,
Kprepresents a scaling factor; t isIRepresents integration time in seconds; t isDRepresents differential time in seconds; t denotes the sampling period in seconds.
The fourth step: the corrected jet pulsewidth t (n +1) is calculated and stored in the MAP.
t(n+1)＝t(n)+Δt(n)。
Claims (1)
1. A method for on-line mixing of combustible gas in a gas engine, characterized in that the method comprises the steps of:
the first step is as follows: m groups of injection rails are arranged at the position, close to an air valve, of an engine intake manifold and respectively correspond to m gas components of the mixed gas, and the volume fraction of the gas 1 is vf1Volume fraction of gas 2 is vf2… …, volume fraction of gas m is vfmThen vf1+vf2+...+vfm1, wherein the injection rail 1 is controlled by an engine ECU, and the other m-1 groups of injection rails are respectively controlled by m-1 control units;in addition, a pressure reducing valve with temperature and pressure sensors is arranged between the injection rail and the engine ECU or the control unit, namely a pressure reducing valve 1, a pressure reducing valve 2, a pressure reducing valve … … and a pressure reducing valve m;
the second step is that: according to throttle opening of engineThe engine speed n, the initial jet pulse width T of the engine is determined by searching the MAP, and the temperature T measured by the pressure reducing valve 1 is used as the basis1Pressure p1Correcting the jet pulse width t, wherein the corrected jet pulse width is t1Thereby controlling the air injection of the injection rail 1;
the third step: the control unit 1 acquires an initial jet pulse width t of an engine ECU (electronic control Unit), and calculates the initial jet pulse width t 'of the injection rail 2 according to the volume fractions of gas 1 and gas 2'2：
At the same time, according to the temperature T measured by the pressure reducing valve 22Pressure p2Initial jet pulsewidth t 'to jet rail 2'2Corrected to have a jet pulse width t2；
Respectively calculating and correcting to obtain the jet pulse width t from the jet rail 3 to the jet rail m by using the same method3、t4、...、tm；
The fourth step: the excess air factor λ is measured using a linear oxygen sensor and the theoretical ECU initial jet pulsewidth t ″ is calculated when λ is 1:
t″＝t×λ
and correcting the initial jet pulse width by using the incremental PID controller according to the difference value between the initial jet pulse width t and the calculated theoretical jet pulse width t' under the condition of meeting a certain condition, so that the engine operates in the state of the optimal air-fuel ratio.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410563059.1A CN104405509B (en) | 2014-10-21 | A kind of method of gas engine on-line mixing fuel gas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410563059.1A CN104405509B (en) | 2014-10-21 | A kind of method of gas engine on-line mixing fuel gas |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104405509A true CN104405509A (en) | 2015-03-11 |
| CN104405509B CN104405509B (en) | 2017-01-04 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105927406A (en) * | 2016-05-04 | 2016-09-07 | 山东大学 | Multi-point gas electric control spraying system and method based on pressure-time control |
| CN107023413A (en) * | 2017-04-13 | 2017-08-08 | 东风商用车有限公司 | Gas quality self-learning device of natural gas engine and using method thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006250141A (en) * | 2005-02-14 | 2006-09-21 | Mazda Motor Corp | Open failure detection system for gas-fuel injection valve |
| CN101370681A (en) * | 2006-05-12 | 2009-02-18 | 欧陆汽车有限责任公司 | Process and device for determining the composition of the gas mixture of the fuel tank of a motor vehicle filled with a CNG gas |
| US20110077847A1 (en) * | 2009-09-25 | 2011-03-31 | Soren Andrew Barr | System, method, and apparatus for gas engine enhanced starting |
| CN103047035A (en) * | 2012-12-13 | 2013-04-17 | 浙江大学 | Coke-oven gas engine self-adaption air-fuel ratio control method based on UEGO (Universal Exhaust Gas Oxygen) |
| CN104033310A (en) * | 2014-06-12 | 2014-09-10 | 浙江大学 | Method for adjusting ignition advance angle of coke-oven gas engine by means of component detection |
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006250141A (en) * | 2005-02-14 | 2006-09-21 | Mazda Motor Corp | Open failure detection system for gas-fuel injection valve |
| CN101370681A (en) * | 2006-05-12 | 2009-02-18 | 欧陆汽车有限责任公司 | Process and device for determining the composition of the gas mixture of the fuel tank of a motor vehicle filled with a CNG gas |
| US20110077847A1 (en) * | 2009-09-25 | 2011-03-31 | Soren Andrew Barr | System, method, and apparatus for gas engine enhanced starting |
| CN103047035A (en) * | 2012-12-13 | 2013-04-17 | 浙江大学 | Coke-oven gas engine self-adaption air-fuel ratio control method based on UEGO (Universal Exhaust Gas Oxygen) |
| CN104033310A (en) * | 2014-06-12 | 2014-09-10 | 浙江大学 | Method for adjusting ignition advance angle of coke-oven gas engine by means of component detection |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105927406A (en) * | 2016-05-04 | 2016-09-07 | 山东大学 | Multi-point gas electric control spraying system and method based on pressure-time control |
| CN105927406B (en) * | 2016-05-04 | 2018-09-28 | 山东大学 | Multi-point gas electric-controlling injection system and method based on pressure versus time control |
| CN107023413A (en) * | 2017-04-13 | 2017-08-08 | 东风商用车有限公司 | Gas quality self-learning device of natural gas engine and using method thereof |
| CN107023413B (en) * | 2017-04-13 | 2023-02-28 | 东风商用车有限公司 | Gas quality self-learning device of natural gas engine and using method thereof |
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