CN104912679A - Engine tail gas treatment method and device - Google Patents
Engine tail gas treatment method and device Download PDFInfo
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- CN104912679A CN104912679A CN201510233284.3A CN201510233284A CN104912679A CN 104912679 A CN104912679 A CN 104912679A CN 201510233284 A CN201510233284 A CN 201510233284A CN 104912679 A CN104912679 A CN 104912679A
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- operating mode
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Abstract
The embodiment of the invention provides an engine tail gas treatment method and device. The method comprises the steps that when an engine is in a lean burn treatment working condition, whether the engine meets a first switching strategy or not is judged; if yes, the engine is switched to a rich burn treatment working condition; when the engine is in the rich burn treatment working condition, whether the engine meets a second switching strategy or not is judged, and if yes, the engine is switched to a lean burn treatment working condition; under the lean burn treatment working condition, nitrogen element is stored in a nitrate or nitrite mode; under the rich burn treatment working condition, the nitrogen element is released from the nitrate or nitrite and restored to nitrogen.
Description
Technical field
The present invention relates to technical field of engines, particularly a kind of motor exhaust processing method and device.
Background technique
In present stage, the reduction treatment technology of common motor exhaust has SCR (Selective CatalyticReduction, selective catalytic reduction technology), EGR (Exhaust Gas Recycle, EGR Technology) and NSR (NO
xstorage and Reduction, stores reductive NO
xtechnology).
In the middle of this three, SCR is applied in the large-duty engine of more than 4L more.EGR is adopted for small displacement engine then more.But due to the restriction of EGR efficiency, only can meet the requirement of state four standard, for state five, state six standard, EGR technology is then difficult to meet.NSR goes for small displacement engine equally, but NSR is very high for the requirement of catalyzer, so be subject to the restriction of catalyzer, causes NSR to be difficult to be applied fully.
Visible, the defect that prior art exists is, for small displacement engine, cannot carry out effect vent gas treatment up to standard.
Summary of the invention
In view of this, the object of the present invention is to provide a kind of motor exhaust processing method and device, by adjusting the air inflow of motor, motor is switched between fuel-rich process operating mode and lean-burn process operating mode, and complete the reduction treatment scheduled to last.
For achieving the above object, the present invention has following technological scheme:
A kind of motor exhaust processing method, described method comprises:
When motor is in lean-burn process operating mode, then judge whether described motor meets the first switchover policy, if met, then described motor is switched to fuel-rich process operating mode;
When described motor is in fuel-rich process operating mode, then judge whether described motor meets the second switchover policy, if met, then described motor is switched to lean-burn process operating mode;
Under described lean-burn process operating mode, nitrogen element is stored with the form of nitrate or nitrite; Under described fuel-rich process operating mode, liberating nitrogen element from nitrate or nitrite, and be reduced to nitrogen.
Preferably, under described lean-burn process operating mode, the chemical equation that nitrogen element stores with the form of nitrate is specially:
Preferably, under described fuel-rich process operating mode, liberating nitrogen element from nitrate, and the chemical equation being reduced to nitrogen is specially:
Preferably, describedly judge whether described motor meets the first switchover policy and be specially:
According to the concentration of nitrogen oxide before and after described lean-burn process operating mode, calculate lean-burn filling rate; When described lean-burn filling rate is lower than the filling rate threshold value preset, then thinks and meet described first switchover policy.
Preferably, describedly judge whether described motor meets the second switchover policy and be specially:
According to the concentration of nitrogen oxide before and after described fuel-rich process operating mode, calculate fuel-rich filling rate; When described fuel-rich filling rate is higher than the filling rate threshold value preset, then thinks and meet described second switchover policy;
Or, when fuel-rich process operating mode exceedes default time threshold working time, then think and meet described second switchover policy.
Preferably, describedly described motor is switched to fuel-rich process operating mode and is specially:
Reduce the air inflow of described motor, make the fuel-rich air fuel ratio that the middle air fuel ratio of described motor reaches default;
The injection advance angle of motor is set as the fuel-rich injection advance angle demarcated in advance.
Preferably, the described lean-burn process operating mode that switched to by described motor is specially:
Increase the air inflow of described motor, make the lean-burn air fuel ratio that the middle air fuel ratio of described motor reaches default;
The injection advance angle of motor is set as the lean-burn injection advance angle demarcated in advance.
Present invention also offers a kind of engine exhaust gas processing unit, described device comprises:
Judge module, during for being in lean-burn process operating mode at motor, judges whether described motor meets the first switchover policy; Or when described motor is in fuel-rich process operating mode, judge whether described motor meets the second switchover policy;
Handover module, for when motor meets described first switchover policy, switches to fuel-rich process operating mode by described motor; Or when motor meets described second switchover policy, described motor is switched to lean-burn process operating mode;
Under described lean-burn process operating mode, nitrogen element is stored with the form of nitrate or nitrite; Under described fuel-rich process operating mode, liberating nitrogen element from nitrate or nitrite, and be reduced to nitrogen.
Preferably, under described lean-burn process operating mode, the chemical equation that nitrogen element stores with the form of nitrate is specially:
Preferably, under described fuel-rich process operating mode, liberating nitrogen element from nitrate, and the chemical equation being reduced to nitrogen is specially:
As seen through the above technical solutions, the beneficial effect that the present invention exists is: by hocketing of lean-burn process operating mode and fuel-rich process operating mode, realize when not needing special catalyst, the dusty gass such as the oxycarbide in motor exhaust, nitrogen oxide, hydro carbons and hydrogen are oxidized or reduction treatment; And can be applied in small displacement engine, reach the requirement of state five, state six standard.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technological scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is method flow diagram described in the embodiment of the present invention;
Fig. 2 is apparatus structure schematic diagram described in the embodiment of the present invention.
Embodiment
For making the object of the embodiment of the present invention, technological scheme and advantage clearly, below in conjunction with the accompanying drawing in the embodiment of the present invention, technological scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
First it should be noted that, in overall plan of the present invention, will relate to lean-burn process operating mode and fuel-rich process operating mode two kinds of engine operation conditions, is also distinctive two kinds of operating modes in the present invention.From the angle of vent gas treatment, described motor by the reciprocal switching under two kinds of operating modes, achieves the process for tail gas just.Below will be specifically described two kinds of operating modes.
So-called lean-burn process operating mode, is equal to the operating conditions of motor routine substantially.Under lean-burn process operating mode, air input of engine by air is large, and air fuel ratio is higher, so oxygen content is high in tail gas.The flammable materials such as oxycarbide, hydro carbons, hydrogen are oxidized easily via burning, generate carbon dioxide and water.But nitrogen oxide can not get effectively reducing.
So under lean-burn process operating mode, by the nitrogen element in nitrogen oxide, can be stored in the middle of catalyzer with the form of nitrate or nitrous acid.Detailed process is, NO is oxidized to NO under catalyst action
2, NO
2react with the compound in catalyzer and form nitrate or nitrite, thus be stored in the catalyst.And research finds, often generate nitrite, and temperature often generates nitrate higher than when 300 DEG C when temperature is lower.The chemical equation that nitrogen element stores with nitrate salts is specific as follows:
Along with the operation of lean-burn process operating mode, nitrogen element is by temporary transient storage.
So-called fuel-rich process operating mode is that nitrogen element is thoroughly reduced to the stage of nitrogen.Under fuel-rich process operating mode, air input of engine by air is little, and air fuel ratio is lower, so oxygen content is low in tail gas.Oxycarbide, hydro carbons, hydrogen etc. have the no longer direct burned oxidation of material of reducibility, but have participated in the chemical reaction of nitrogen element reduction.
But because oil consumption under fuel-rich process operating mode is large, can not maintain for a long time, so in the present invention, nitrogen element will after a certain amount of storage, reduces in the time concentrating on fuel-rich process operating mode.Namely lean-burn process operating mode is switched back after having reduced.
Under fuel-rich process operating mode, liberating nitrogen element from nitrate, and the chemical equation being reduced to nitrogen is specially:
Thus, along with hocketing of lean-burn process operating mode and fuel-rich process operating mode, the dusty gass such as oxycarbide to be processed, nitrogen oxide, hydro carbons and hydrogen in motor exhaust, are needed all to obtain oxidation or reduction treatment.And in above-mentioned principle, do not need special catalyzer; Also can confirm by experiment, aforesaid way can be applied in small displacement engine smoothly, and vent gas treatment efficiency can reach the requirement of state five, state six standard.
Based on the principle of above lean-burn process operating mode and fuel-rich process operating mode, a kind of motor exhaust processing method in the embodiment of the present invention, will be provided; Described method achieves and above-mentioned operating mode principle is applied in the middle of the vent gas treatment of small displacement engine.With reference to shown in Fig. 1, described method specifically comprises:
Step 101, when motor is in lean-burn process operating mode, then judge whether described motor meets the first switchover policy, if met, then described motor is switched to fuel-rich process operating mode.
In this step, motor normally runs, and namely thinks to be in lean-burn process operating mode, period nitrogen element be constantly stored in catalyzer with the form of nitrate.When nitrogen element is stored into a certain degree, namely think to meet the first switchover policy.Putting before this, described motor is being switched to fuel-rich process operating mode, starting the reduction carrying out nitrogen element.
Described first switchover policy is for standard with the filling rate of nitrogen element.That is, judge whether described motor meets the first switchover policy and be specially: according to the concentration of nitrogen oxide before and after described lean-burn process operating mode, calculate lean-burn filling rate; When described lean-burn filling rate is lower than the filling rate threshold value preset, then thinks and meet described first switchover policy.In fact, when the storage of nitrogen element is reduced to default filling rate threshold value once, then illustrate that the storage of nitrogen element is close to saturated, must be switched to fuel-rich process operating mode, the nitrogen element started storing reduces, to ensure that the process of tail gas can be up to standard.
So-called lean-burn process operating mode and fuel-rich process operating mode, namely essential distinction is air fuel ratio.So lean-burn process operating mode is switched to fuel-rich process operating mode, be in fact exactly the air inflow reducing described motor, make the fuel-rich air fuel ratio that the middle air fuel ratio of described motor reaches default.In the present embodiment, set described fuel-rich air fuel ratio and be less than 14.3.
And it is preferred, in order to raise the delivery temperature of motor, optimize the burning of motor, then can also demarcate a fuel-rich injection advance angle in advance for fuel-rich process operating mode in the present embodiment, and after being switched to fuel-rich process operating mode, the injection advance angle of motor is set as described fuel-rich injection advance angle.
Step 102, when described motor is in fuel-rich process operating mode, then judge whether described motor meets the second switchover policy, if met, then described motor is switched to lean-burn process operating mode.
Aforementionedly illustrate, under fuel-rich process operating mode, oil consumption is comparatively large, if the long-time Economy continuing destruction motor that will inevitably be serious.So only store close to saturated at nitrogen element, run a period of time under just needing motor to be switched to fuel-rich process operating mode, the nitrogen element stored before is effectively reduced.
So under fuel-rich process operating mode, also need to judge whether described motor meets the second switchover policy, if met, then described motor is switched back lean-burn process operating mode.Specifically, when meeting one of two conditions, can think to meet the second switchover policy:
One is the concentration according to nitrogen oxide before and after described fuel-rich process operating mode, calculates fuel-rich filling rate; When described fuel-rich filling rate is higher than the filling rate threshold value preset, then thinks and meet described second switchover policy.Principle is with described first switchover policy, that is when the filling rate of nitrogen element improves significantly, then the reduction reaction by certain hour is described, has made nitrogen unit have enough storage spaces, then can switch back lean-burn process operating mode, re-start the storage of nitrogen element.
Another for exceeding default time threshold working time when fuel-rich process operating mode, is then thought and meets described second switchover policy.The working time being fuel-rich process operating mode specifies a time threshold, once reach time threshold, thinks that the reduction reaction of nitrogen element completes substantially, namely stops fuel-rich process operating mode, switch back lean-burn process operating mode.
Fuel-rich process operating mode, to the process of lean-burn process operating mode, is the inverse process that lean-burn process operating mode switches to fuel-rich process operating mode, recovers reduction completely, be not repeated herein by air inflow, air fuel ratio and injection advance angle three factors.
In the present embodiment, by switching and the alternate run of two kinds of operating modes, effectively motor exhaust is processed.As seen through the above technical solutions, the beneficial effect that the present embodiment exists is: by hocketing of lean-burn process operating mode and fuel-rich process operating mode, realize when not needing special catalyst, the dusty gass such as the oxycarbide in motor exhaust, nitrogen oxide, hydro carbons and hydrogen are oxidized or reduction treatment; And can be applied in small displacement engine, reach the requirement of state five, state six standard.
Shown in Figure 2, for the specific embodiment of device of the present invention, in the present embodiment device be used for realizing embodiment illustrated in fig. 1 described in method, its technological scheme is consistent with embodiment illustrated in fig. 1 in essence, and in previous embodiment, corresponding description is equally applicable in the present embodiment.Described device specifically comprises:
Judge module, during for being in lean-burn process operating mode at motor, judges whether described motor meets the first switchover policy; Or when described motor is in fuel-rich process operating mode, judge whether described motor meets the second switchover policy.
Handover module, for when motor meets described first switchover policy, switches to fuel-rich process operating mode by described motor; Or when motor meets described second switchover policy, described motor is switched to lean-burn process operating mode.
Under described lean-burn process operating mode, nitrogen element is stored with the form of nitrate or nitrite; Under described fuel-rich process operating mode, liberating nitrogen element from nitrate or nitrite, and be reduced to nitrogen.
Under described lean-burn process operating mode, the chemical equation that nitrogen element stores with the form of nitrate is specially:
Under described fuel-rich process operating mode, liberating nitrogen element from nitrate, and the chemical equation being reduced to nitrogen is specially:
In the present embodiment, by switching and the alternate run of two kinds of operating modes, effectively motor exhaust is processed.As seen through the above technical solutions, the beneficial effect that the present embodiment exists is: by hocketing of lean-burn process operating mode and fuel-rich process operating mode, realize when not needing special catalyst, the dusty gass such as the oxycarbide in motor exhaust, nitrogen oxide, hydro carbons and hydrogen are oxidized or reduction treatment; And can be applied in small displacement engine, reach the requirement of state five, state six standard.
The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (10)
1. a motor exhaust processing method, is characterized in that, described method comprises:
When motor is in lean-burn process operating mode, then judge whether described motor meets the first switchover policy, if met, then described motor is switched to fuel-rich process operating mode;
When described motor is in fuel-rich process operating mode, then judge whether described motor meets the second switchover policy, if met, then described motor is switched to lean-burn process operating mode;
Under described lean-burn process operating mode, nitrogen element is stored with the form of nitrate or nitrite; Under described fuel-rich process operating mode, liberating nitrogen element from nitrate or nitrite, and be reduced to nitrogen.
2. method according to claim 1, is characterized in that, under described lean-burn process operating mode, be specially by the chemical equation that nitrogen element stores with the form of nitrate:
3. method according to claim 1, is characterized in that, under described fuel-rich process operating mode, and liberating nitrogen element from nitrate, and the chemical equation being reduced to nitrogen is specially:
4. method according to claims 1 to 3 any one, is characterized in that, describedly judges whether described motor meets the first switchover policy and be specially:
According to the concentration of nitrogen oxide before and after described lean-burn process operating mode, calculate lean-burn filling rate; When described lean-burn filling rate is lower than the filling rate threshold value preset, then thinks and meet described first switchover policy.
5. method according to claims 1 to 3 any one, is characterized in that, describedly judges whether described motor meets the second switchover policy and be specially:
According to the concentration of nitrogen oxide before and after described fuel-rich process operating mode, calculate fuel-rich filling rate; When described fuel-rich filling rate is higher than the filling rate threshold value preset, then thinks and meet described second switchover policy;
Or, when fuel-rich process operating mode exceedes default time threshold working time, then think and meet described second switchover policy.
6. method according to claims 1 to 3 any one, is characterized in that, describedly described motor is switched to fuel-rich process operating mode and is specially:
Reduce the air inflow of described motor, make the fuel-rich air fuel ratio that the middle air fuel ratio of described motor reaches default;
The injection advance angle of motor is set as the fuel-rich injection advance angle demarcated in advance.
7. method according to claims 1 to 3 any one, is characterized in that, the described lean-burn process operating mode that switched to by described motor is specially:
Increase the air inflow of described motor, make the lean-burn air fuel ratio that the middle air fuel ratio of described motor reaches default;
The injection advance angle of motor is set as the lean-burn injection advance angle demarcated in advance.
8. an engine exhaust gas processing unit, is characterized in that, described device comprises:
Judge module, during for being in lean-burn process operating mode at motor, judges whether described motor meets the first switchover policy; Or when described motor is in fuel-rich process operating mode, judge whether described motor meets the second switchover policy;
Handover module, for when motor meets described first switchover policy, switches to fuel-rich process operating mode by described motor; Or when motor meets described second switchover policy, described motor is switched to lean-burn process operating mode;
Under described lean-burn process operating mode, nitrogen element is stored with the form of nitrate or nitrite; Under described fuel-rich process operating mode, liberating nitrogen element from nitrate or nitrite, and be reduced to nitrogen.
9. device according to claim 8, is characterized in that, under described lean-burn process operating mode, be specially by the chemical equation that nitrogen element stores with the form of nitrate:
10. device according to claim 8, is characterized in that, under described fuel-rich process operating mode, and liberating nitrogen element from nitrate, and the chemical equation being reduced to nitrogen is specially:
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5426934A (en) * | 1993-02-10 | 1995-06-27 | Hitachi America, Ltd. | Engine and emission monitoring and control system utilizing gas sensors |
| US6109024A (en) * | 1997-05-12 | 2000-08-29 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification device for an internal combustion engine |
| CN1580528A (en) * | 2003-07-31 | 2005-02-16 | 日产自动车株式会社 | Engine fuel injection control apparatus |
| CN101091039A (en) * | 2004-12-23 | 2007-12-19 | 乌米科雷股份两合公司 | Method for monitoring the nitrogen oxide storage capacity of a nitrogen oxide storage catalyst used in the form of a primary catalytic converter |
| CN101137830A (en) * | 2005-03-18 | 2008-03-05 | 丰田自动车株式会社 | Exhaust gas purification system for an internal combustion engine |
-
2015
- 2015-05-08 CN CN201510233284.3A patent/CN104912679A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5426934A (en) * | 1993-02-10 | 1995-06-27 | Hitachi America, Ltd. | Engine and emission monitoring and control system utilizing gas sensors |
| US6109024A (en) * | 1997-05-12 | 2000-08-29 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification device for an internal combustion engine |
| CN1580528A (en) * | 2003-07-31 | 2005-02-16 | 日产自动车株式会社 | Engine fuel injection control apparatus |
| CN101091039A (en) * | 2004-12-23 | 2007-12-19 | 乌米科雷股份两合公司 | Method for monitoring the nitrogen oxide storage capacity of a nitrogen oxide storage catalyst used in the form of a primary catalytic converter |
| CN101137830A (en) * | 2005-03-18 | 2008-03-05 | 丰田自动车株式会社 | Exhaust gas purification system for an internal combustion engine |
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Application publication date: 20150916 |