CN1271319C - Method and apparatus for desulfurizing pre-catalyst - Google Patents
Method and apparatus for desulfurizing pre-catalyst Download PDFInfo
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- CN1271319C CN1271319C CN 02119321 CN02119321A CN1271319C CN 1271319 C CN1271319 C CN 1271319C CN 02119321 CN02119321 CN 02119321 CN 02119321 A CN02119321 A CN 02119321A CN 1271319 C CN1271319 C CN 1271319C
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Abstract
The invention relates to a method for desulphurizing at least one pre-catalyst (16) arranged in an exhaust gas duct (14) of an internal combustion engine (10), wherein the pre-catalyst is followed by at least one further catalyst (18), in particular a NOx storage catalyst, and to a device for carrying out the method. At or during the pre-process before the pre-catalyst (16) temperature is reached, said pre-catalyst temperature being at least equal to the minimum sulphur desorption temperature of the pre-catalyst (16), (a) during the first phase (τ)1) The internal combustion engine (10) combusts in a first rich combustion lambda (lambda)F1) Working until the oxygen storage of the downstream catalyst (18) is at least largely free of oxygen, and (b) in a subsequent second phase (τ)2) The internal combustion engine (10) alternately operates at a lean combustion lambda value (lambda)M) Lean interval (τ)M) And at a second rich burn lambda value (lambda)F2) Rich interval (τ) ofF) And (6) working.
Description
Technical field
The present invention relates to a kind of method of the pre-catalyst in the exhaust gas channel that is arranged on internal-combustion engine being carried out desulfurization, wherein this pre-catalyst is equipped with another catalyzer after at least, NOx-storage catalyst particularly, the invention still further relates to a kind of to being arranged on the device that can carry out desulfurization with the pre-catalyst in the exhaust gas channel of the internal-combustion engine of poor mode work, wherein this pre-catalyst is equipped with another catalyzer after at least, particularly a NOx-storage catalyst.
Background technique
The antigravity system that becomes known for tail gas clean-up comprises that mostly at least one pre-catalyst that is arranged near the little volume of motor is arranged on the bigger primary catalyst in downstream far away in the exhaust gas channel with at least one.Wherein the composition of catalyzer can be to be used for oxidation catalyst that unburned hydrocarbon HC and carbon monoxide CO are transformed, be used for reducing catalyst or three-way catalyst that nitrogen oxides NOx is reduced, described three-way catalyst impels simultaneously and carries out described oxidation and reduction transforms.Primary catalyst can add and have NOx-storage catalyst part under can be with the situation of the internal-combustion engine of poor mode work, described NOx-storage catalyst part is with the sky-combustion-mixed gas of the oxygen enrichment of the λ＞1 poor working method stage to the internal-combustion engine air feed, with the nitrate mode irreversible nitrogen oxide NOx is stored and in the richness regeneration interval of intermediate controlled again with its release and reduction.This class catalyzer also is known as the NOx-storage catalyst.
Known problem when tail gas clean-up is the sulphur that contains in fuel, and this sulphur is almost become sulfur dioxide SO by perfect combustion in combustion process
2And be stored in a different manner in the various parts of antigravity system.This problem is particularly related to the NOx-storage area of NOx-storage catalyst system, and this NOx-storage component will be with 100% storage efficiency almost to SO when poor burning λ
2Store in the sulphate mode.Has very high temperature stability based on it, so in the NOx-regenerative process of regularly carrying out, sulphate can not be separated in by storage.Its result will cause the NOx-storage capacity of storage catalyst by progressively deactivation (sulfur poisoning), thereby will need the NOx-storage catalyst is taked various sweetening processes.For realize that desulfurization will load catalyzer with a rich exhaust gas environment when catalyst temperature is at least 600 ℃, so that the sulphate that stores is carried out desorb and mainly is reduced into SO
2With hydrogen sulfide H
2S.In DE 198 27 195A or DE 198 35 808A, disclosed alternative continuous richness loading in addition and alternately carried out desulfurization, so that to the strong H of smell with poor-Fu-interval to the NOx-storage catalyst
2The discharging of S is offset.Adopt suitable interval design, then can almost completely can realize comparing SO
2-generation want slow H
2The generation of S-.
Except the NOx-storage area is vulcanized, also can sulphur be stored in the other parts of antigravity system trace ground certainly.These parts mainly are the inert metal (Pt, Pd, Rh) of the attached layer of catalysis and the part of O SC (oxygen storage area) of storage oxygen.Inhale temperature (OSC is approximately 400 to 450 ℃ and inert metal and is approximately 500 ℃) when catalyst temperature is higher than sector-specific thiolysis, and under the rich exhaust gas environment, will realize the discharge of the sulphur of storage.At this disadvantageously, by pre-catalyst with H
2S and SO
2The sulphur that form discharges is owing to having aerobic thereby will be stored once more by the part of the catalyzer of postposition in the catalyzer of postposition.If what relate at this is the NOx-storage catalyst, then will be stored fully.Its result will cause must be often to the primary catalyst desulfurization and therefore will cause high oil consumption.
In patent application DE 100 59 791.2 formerly, disclosed a kind of method that is used for the pre-catalyst desulfurization, wherein mainly with hydrogen sulfide H
2The sulphur that the S form stores is discharged from, and described hydrogen sulfide especially can not be stored in the primary catalyst of anaerobic in the rearmounted primary catalyst, but the overwhelming majority is passed primary catalyst under prevailing operating conditions.At primary catalyst to a great extent before the anaerobic, internal-combustion engine is at first worked in enriched combustion λ mode for this reason.Then the sulphur that will be stored in the pre-catalyst under the situation of only omiting rich burning λ is discharged.Because the punctum primary catalyst is not contain aerobic at this moment, the sulphur that then is discharged from can't be by primary catalyst oxidation and storage.The shortcoming of this method is that reducing agent HC and CO will follow rich mode of operation passing and H to a certain degree to occur
2The discharging of S.
Summary of the invention
The objective of the invention is to propose a kind of method that pre-catalyst is carried out desulfurization, this method will make rearmounted primary catalyst be subjected to the least possible sulfuration and will reduce H on big as far as possible degree
2Emission of harmful substances such as S, HC and CO.A kind of corresponding exhaust system of implementing this method has also been proposed in addition.
Take a kind of method that the pre-catalyst that is arranged at least in the exhaust gases of internal combustion engines passage is carried out desulfurization of being used for according to the present invention, behind this pre-catalyst, be connected to another catalyzer at least, a NOx-storage catalyst particularly, it is characterized in that, when reaching the pre-catalyst temperature or reaching in the pre-process before the pre-catalyst temperature, described pre-catalyst temperature is greater than or equal to the minimum thiolysis of pre-catalyst temperature and inhales temperature
(a) before the oxygen storage of the catalyzer of postposition does not contain aerobic at least to a great extent, the phase I internal-combustion engine always with first enriched combustion λ work and
(b) alternately work at the second stage internal-combustion engine of following at poor interval with at rich interval with second enriched combustion λ with poor burning λ.
The present invention utilizes following situation, such as the sulfur dioxide SO that is discharged by pre-catalyst under the tail gas environment of few oxygen of richness
2To a large extent only on the NOx-storage of part (OSC) that just can be stored in storage oxygen under the condition of aerobic and/or rearmounted catalyzer, this is because storage at first needs sulphur is oxidized to the oxide of sexavalence Deng the exhaust gas component of sulfur-bearing.So the desulfurization of pre-catalyst divides two stages to carry out, wherein phase I of method by whole antigravity system, particularly to a great extent oxygen is separated by the oxygen storage of the catalyzer of postposition and second stage by pre-catalyst in sulphur, specifically with SO
2The sulphur of form is discharged.
The oxygen storage capacity (oxygen emptying) after the phase I of rearmounted catalyzer should occupiedly at most reach 20%, preferably takies to be less than 10%.The process of the discharge of oxygen can be monitored with the oxysensible measuring device that simple mode utilization is arranged on rearmounted catalyzer downstream.Wherein this measuring device can be λ probe or, particularly can be NOx-sensor under the situation of NOx-storage catalyst with λ measurement function.Needn't reach thiolysis at the phase I pre-catalyst and inhale temperature.
The burning λ that selects should be low as much as possible in the phase I, and promptly oxygen should lack as much as possible.Wherein especially the λ value is 0.7 to 0.95, and preferred 0.8 to 0.9 is proved to be useful.These λ values will cause the discharge by the very quick and creationary oxygen of antigravity system.
Alternately pre-catalyst is loaded with lean exhaust gas environment and rich exhaust gas environment in the second stage of following.Load with continuous richness and to compare, this hocket poor-/the rich advantage that loads is, the poor interval of inserting by the centre have a certain amount of oxygen to add in the pre-catalyst all the time and therefore richness be released out at interval mainly with SO
2The sulphur that form exists is discharged from.Can realize H to a great extent in this way in contrast
2The inhibition that S generates.Wherein the design to poor interval should make oxygen can not pass pre-catalyst, thereby can avoid oxygen to be stored in again in a plurality of catalyzer of rearmounted catalyzer or postposition.
By can also advantageously promoting SO to the poor interval of second stage and the corresponding design at rich interval
2-discharge.Can adopt the multiple scheme of this method for this reason.Carry out poor interval and rich conversion between at interval according to particularly preferred design in λ adjustment mode.Wherein in case the tail gas λ in the downstream side of pre-catalyst reaches first predetermined threshold value, especially poor threshold value then is transformed at interval rich by poor interval.In contrast, in case reach one second predetermined threshold at the tail gas λ in the downstream side of pre-catalyst, particularly rich threshold value is then carried out by richness at interval to the conversion at poor interval.Preferred adopt oxysensible measuring device, especially rank that are arranged on the pre-catalyst downstream to get over function response-or broadband-λ probe.Adjustment both can accurately be controlled to the adding of pre-catalyst oxygen in the poor interval by λ, can suppress passing of harmful matter (CO and HC) to a great extent again.Wherein the only slightly rich λ value of the predetermined value of the richness second enriched combustion λ at interval is proved to be useful especially.Especially when the λ value be 0.93 to 0.995, be preferably at 0.97 to 0.99 o'clock, will cause passing of harmful matter low especially and cause to H
2The actual complete inhibition of S.
Also can be implemented in to timing controlled poor-and rich at interval the conversion of second stage under the at interval predetermined at a fixed time in addition situation, wherein the second enriched combustion λ of Xuan Zeing can be identical with the conversion of λ adjustment.Wherein verified rich interlude length between 1 to 20 second, especially between 2 to 10 seconds and poor interlude length at 0.5 to 10 second, especially between 2 to 6 seconds.As this method another program by poor interval to richness conversion at interval also can be at the latest in case carry out when measuring lean exhaust gas λ in the catalyzer downstream of postposition.
According to one of the inventive method useful especially design, before desulfurization end and internal-combustion engine insert regular mode of operation again, before pre-catalyst does not contain aerobic at least to a great extent, keep second stage always.For this reason can be to the discharge of the adding of the sulphur of pre-catalyst and/or sulphur modelling continuously, thus obtain total useful load of the sulphur of pre-catalyst.Should work as model and calculate and to illustrate when pre-catalyst predetermined, sulphur was emptied completely to a great extent, realize the conversion of the end of second stage and internal-combustion engine to regular poor working method.Can be with known, the mode that does not repeat them here is by the running parameter of internal-combustion engine reality, especially realizes the modelling of the discharge of the adding of sulphur and sulphur by combustion parameter.
Can utilize one be arranged on the pre-catalyst, be arranged on the temperature of the temperature sensor measurement pre-catalyst before or after the pre-catalyst or under the situation of considering the corresponding work parameter, obtain model and calculate.Also carry out prediction (diagnosis) in addition according to one of the inventive method useful especially design to the pre-catalyst temperature at a specific following period.If because a temperature rising is especially rapidly diagnosed whether reach thiolysis suction temperature in the time period by prediction, thereby before pre-catalyst reaches desorption temperature, can be begun the phase I of pre-catalyst desulfurization.Employing can be at the desorption temperature of or all pre-catalyst part partly or even carry out the separation of oxygen of the phase I of method fully in this mode.Preferably the position of the pedal value generator (PWG) of considering gas pedal, pedal value generator dynamically, the true temperature of the rotating speed of motor, the amount of fuel that sprays into, pre-catalyst, pre-catalyst temperature dynamically, the modeled sulphur of pre-catalyst loads and/or the oxygen of pre-catalyst stores under the active situation pre-catalyst temperature is predicted.
According to useful especially a enforcement, the first and/or second enriched combustion λ, poor burning λ and/or first and/or second threshold value are scheduled to according to above-mentioned parameter to the inventive method.In addition or be attached to consider rearmounted catalyzer situation under to the λ in first and second stages-and the threshold predetermined value be scheduled to.Active in this temperature and/or temperature dynamic, modeled sulphur loading, conversion activity and/or oxygen storage that at first relates to rearmounted catalyzer.
Since at internal-combustion engine with poor service requirement under common working state, need at interval rich for various reasons termly, it is preferred as long as the pre-catalyst temperature surpasses thiolysis suction temperature, then at the desulfurization of the present invention, utilize a kind of like this " nature " rich working stage and design according to described predetermined value to pre-catalyst.Adopt this mode, can carry out desulfurization pre-catalyst with minimum oil consumption.Under situation, particularly can utilize NOx-regeneration to realize that at interval desulfurization or the desulfurization to catalyzer of the present invention is right after after regeneration and carries out as the primary catalyst of NOx-storage catalyst design.But also can associate the rich interval of the pressure amplitude of utilization so-called stoichiometrical working method (λ=1) in TWC system.
The further useful design of the inventive method is, especially on driver requested ideal is travelled the operation point of torque less than the displacement torque of Motor Vehicle, and/or during to the pre-catalyst desulfurization to the conversion of the gearbox gear-shift that interrupts at pulling force the displacement intermittently the time interrupt suppressing.Adopt this mode can be by the inhibition that with the tail gas of unusual oxygen enrichment the loading of exhaust system is realized displacement is interrupted.
According to decision design of the present invention, when reaching the pre-catalyst temperature or reaching in the pre-process before the pre-catalyst temperature, described pre-catalyst temperature is greater than or equal to the minimum thiolysis of pre-catalyst temperature and inhales temperature,
(a) before the oxygen storage of the catalyzer of postposition does not contain aerobic at least to a great extent, the phase I internal-combustion engine always with first enriched combustion λ work and
(b) alternately work at the second stage internal-combustion engine of following, wherein poor interval is determined to timing controlled at interval with rich, make with carbon dioxide (SO at poor interval with at rich interval with second enriched combustion λ with poor burning λ
2) form is stored in the sulphur at least 25% in the pre-catalyst, preferably at least 50% be discharged from.
The inventive method is utilized following situation, such as the sulfur dioxide SO that is discharged by pre-catalyst under the tail gas environment of few oxygen of richness
2Deng the exhaust gas component of sulfur-bearing to a large extent only on the NOx-storage of part (OSC) that just can be stored in storage oxygen under the condition of aerobic and/or rearmounted catalyzer, this be because to the sulphur storage of sulphate form at first need with sulphur be oxidized to the oxide of sexavalence so.So the desulfurization of pre-catalyst divides two stages to carry out, wherein phase I of method by whole antigravity system, particularly to a great extent oxygen is separated by the oxygen storage of the catalyzer of postposition and second stage by pre-catalyst in sulphur, specifically with SO
2The sulphur of form is discharged.
Alternately pre-catalyst is loaded with lean exhaust gas environment and rich exhaust gas environment in second stage.Load with continuous richness and to compare, this hocket poor-/the rich advantage that loads is, the poor interval of inserting by the centre has a certain amount of oxygen to add in the pre-catalyst all the time and therefore is released out mainly with SO at interval in richness
2The sulphur that form exists is discharged from.In contrast, can realize H in this way to a great extent to the smell is awful
2The inhibition of S.Wherein should make in fact that oxygen can not pass pre-catalyst, thereby can avoid oxygen to be stored in again in rearmounted catalyzer or the rearmounted a plurality of catalyzer the design at poor interval.
To poor-and rich at interval timing controlled, can adopt the measuring device that is placed on pre-catalyst based on the present invention, λ probe for example, thereby can realize this method with cheap cost.However the alap again storage rate of the sulphur that just discharges on the catalyzer of postposition and low reducing agent-and H
2The discharging of S, can realize the design of the best at interval, wherein according to the oxygen concentration in the tail gas that measure in the catalyzer downstream of postposition at least with following also with the mode described to poor-and the predetermined value of rich interlude length test and carry out adaptive adjustment in case of necessity.
According to one of this method useful especially design, at least to the first poor interval of the second stage of desulfurization and/or the first rich interlude length pre-control value of predetermined variable at first, this variable pre-control value is preferably determined according to the oxygen storage capacity of pre-catalyst and is stored in the characteristic curve group relevant with the operation point.Wherein obtain the oxygen storage capacity of pre-catalyst, i.e. its maximum storable oxygen amount in the ratio of the oxygen storage capacity of at least one rearmounted catalyzer according to the oxygen storage capacity of whole storage system with according to known pre-catalyst.To whole-oxygen storage capacity can be benchmark with the given value of a fresh antigravity system, and described fresh antigravity system is not contain aerobic and sulphur and int antigravity system.Because validity is had relatively high expectations, so preferably determine during the second stage of method begins preceding and/or second stage in method whole antigravity system because the oxygen storage capacity of the reality that aging process often reduces, so that by the oxygen storage capacity of reality known and obtain pre-catalyst as the Capacity Ratio of constant.
Definite should the making in poor interval of the poor interlude length of preferred second stage is stored in oxygen as much as possible on the pre-catalyst when the least possible oxygen passes pre-catalyst.This point is necessary, and sulphur is stored in the rearmounted catalyzer again so that avoid the rearmounted catalyzer of oxygen adding and follow then.Preferably in the poor blanking time of the oxygen storage of pre-catalyst, be full of 30% and be full of 99% at most at least, especially minimumly be full of 50% and be full of 95% oxygen at most.Wherein particularly preferably be, the end at poor interval conforms to a time point basically at the latest, and lean exhaust gas passes pre-catalyst on this time point.
On the other hand, the rich interlude length of Que Dinging should make to be mainly sulfur dioxide SO
2The sulphur that form is stored in the pre-catalyst is discharged from the richness interval.Rich for this reason end at interval should conform to a time point substantially, and the oxygen storage of pre-catalyst is drained to a great extent on this time point, does not promptly contain aerobic.
For obtaining the oxygen storage capacity of whole antigravity system, i.e. the summation of the maximum oxygen storage capacity of each of each catalyzer, can take different, even the measure of combining mutually that is suitable for.According to the mode of execution of the inventive method, the antigravity system that actual maximum oxygen loads is determined that wherein internal-combustion engine becomes rich mode of operation by poor working mode change.To changing the back and the time period before the downstream side of the catalyzer of postposition detects rich exhaust gas is first determined at least.Obtain the oxygen storage capacity of whole antigravity system then according to this time period.To the real work parameter that wherein can also add the substitution internal-combustion engine, for example engine loading or rotating speed for definite whole oxygen storage capacity.Particularly preferably be when the phase I finishes and before second stage tail gas alternately loads, carry out this and determine.Preferred for this reason before the downstream side of the catalyzer of postposition detects lean exhaust gas first, at least at first use slightly poor tail gas, especially load with λ=1.005 to 1.05 pairs of antigravity systems.Then internal-combustion engine is transformed into slightly rich tail gas λ, especially is transformed into the λ value between 0.95 to 0.995, detect rich exhaust gas first until downstream side at the catalyzer of postposition.By obtaining whole oxygen storage capacity from poor conversion until the time delay that rich exhaust gas passes rearmounted catalyzer to richness at internal-combustion engine.The advantage of this mode is in addition, and rearmounted catalyzer then contains aerobic at least hardly, thereby can not be stored in again in the catalyzer of postposition when discharging sulphur in then by pre-catalyst.So useful especially is, before the minimum thiolysis that reaches pre-catalyst is inhaled temperature, especially when being lower than the about 20K of this temperature, carry out the determining of oxygen storage capacity of total system.Adopt this to reality whole oxygen storage capacity regularly can also before carrying out poor-Fu-loading alternately, the pre-control value of the storage relevant with the operation point be verified and revise in case of necessity really.Adopt this mode to realize H
2S discharging and to especially effectively suppressing that the oxygen of the catalyzer of postposition loads.
According to the design of the inventive method second stage in desulfurization, promptly hocket poor and rich additional or in addition whole antigravity system is carried out determining of oxygen storage capacity when changing at interval.Wherein behind a rich interval, promptly contain the poor interval that prolongs under the situation of aerobic hardly at antigravity system, and to being transformed into poor working method at internal-combustion engine and detecting lean exhaust gas at least in the downstream side of the catalyzer of a postposition or surpass that time period between the predetermined poor threshold value is analyzed and its design should make the time point that surpasses poor threshold value relevant with the oxygen storage of the catalyzer that at least almost entirely is full of postposition.
According to another design of the inventive method, in second stage, carrying out of promptly replacing be poor-and detect with adaptive richness pre-control value at interval is additional during rich the loading.On rich λ value direction, measure for this reason and analyze internal-combustion engine by richness at interval to the conversion at poor interval and at least the tail gas λ in the downstream side of the catalyzer of postposition be lower than period between the predetermined rich threshold value.Wherein the design of rich threshold value should make the time point that is lower than rich threshold value at least almost be emptied completely relevant with the oxygen storage of pre-catalyst.
The burning λ that selects in the phase I should be low as far as possible, this means that oxygen should be the least possible.Wherein in particular for 0.7 to 0.95 λ value, preferred 0.8 to 0.9 λ value is verified to be useful.This λ value will cause the rapid especially and creationary discharge by antigravity system oxygen.Predetermined and above-mentioned opposite slightly rich λ value to the richness second enriched combustion λ at interval is useful especially.Particularly when the λ value be 0.93 to 0.995, preferably when the λ value is 0.97 to 0.99, will cause few especially harmful matter pass and to H
2The actual complete inhibition of S.The poor interval of second stage is preferably between 1.0 to 1.2, particularly between 1.02 to 1.04.
After the phase I of oxygen emptying, the oxygen storage capacity of rearmounted catalyzer is the highest occupied 20%, preferred occupiedly is less than 10%.The process that can utilize an oxysensible measuring device that is arranged on rearmounted catalyzer downstream side that oxygen is discharged monitors.Wherein this measuring device relate to a kind of λ probe or, particularly under the situation of NOx-storage catalyst, relate to a kind of NOx-sensor of the λ of having measurement function.In this phase I, pre-catalyst needn't reach thiolysis and inhale temperature.
According to this method one particularly preferred design, before desulfurization end and internal-combustion engine are inserted regular mode of operation again, keep second stage before the oxygen-free at least to a great extent at pre-catalyst always.For this reason can be to the discharge of the adding of the sulphur of pre-catalyst and/or sulphur modelling constantly, thus can obtain the sulphur of pre-catalyst-total loading.Preferably to indicate pre-catalyst one predetermined when model calculates, and for example sulphur is emptied completely to a great extent.Can be with the running parameter of the known mode that does not repeat them here according to the reality of internal-combustion engine, especially according to combustion parameter to the adding of sulphur and the discharge modelling of sulphur.
Utilization is arranged on the pre-catalyst, be arranged on pre-catalyst front or back the temperature sensor measurement pre-catalyst temperature or under the situation of considering the corresponding work parameter, calculate the temperature of obtaining pre-catalyst according to model.Can predict (diagnosis) to the pre-catalyst temperature of period in specific future according to one of this method useful especially design in addition.Inhale temperature when going out because the special rising of temperature rapidly will reach thiolysis in the period, then before pre-catalyst reaches desorption temperature, promptly can begin the phase I of pre-catalyst desulfurization by predictive diagnosis.Adopt this mode under the situation of the desorption temperature that is lower than or all pre-catalyst part, promptly can partly or even carry out the oxygen of this method phase I fully and separate.Preferably the position of the pedal value generator (PWG) of considering gas pedal, pedal value generator dynamically, the true temperature of the rotating speed of motor, the amount of fuel that sprays into, pre-catalyst, pre-catalyst temperature dynamically, the modeled sulphur of pre-catalyst loads and/or the oxygen of pre-catalyst stores the prediction of carrying out the pre-catalyst temperature under the active situation.
Owing to need rich operation range during in common working method termly at internal-combustion engine for various reasons with poor service requirement, so preferably inhale temperature, then utilize " nature " rich working stage to design to pre-catalyst desulfurization of the present invention and according to described predetermined value as long as the pre-catalyst temperature surpasses thiolysis.Adopt this mode to realize desulfurization with minimum oil consumption to pre-catalyst.Under situation, particularly can utilize NOx-regeneration to be used for the desulfurization of the present invention at interval, or be right after after regeneration and carry out desulfurization pre-catalyst as the primary catalyst of NOx-storage catalyst design.In TWC system, utilize the at interval rich of the described pressure amplitude of stoichiometry working method (λ=1) but also can associate.
The further useful design according to the present invention, conversion when to the pre-catalyst desulfurization time, special on an operation point and/or gearbox pulling force being interrupted shifting gears intermittently the time displacement interrupt suppressing the wherein desired displacement torque of desired torque of travelling of driver on described operation point less than Motor Vehicle.Adopting this mode to load exhaust system with the tail gas of unusual oxygen enrichment avoids displacement to interrupt.
The present invention also comprises a kind of device of implementing this method in addition, and this device has an oxysensible measuring device and mechanism in the downstream side of at least one rearmounted catalyzer (primary catalyst), utilizes described mechanism can implement described method step.This mechanism comprises a control unit, stores the algorithm that is used for implementing with digital form this method in this unit.This control unit can strike up partnership with the control section of motor especially.
The present invention comprises a kind of device of implementing this method in addition, and this device has an oxysensible measuring device and mechanism in the downstream side of at least one rearmounted catalyzer (primary catalyst), utilizes described mechanism can implement described method step.This mechanism comprises a control unit, stores the algorithm that is used for implementing with digital form this method in this unit.This control unit can strike up partnership with the control section of motor especially.
Install a particularly preferred design according to this, pre-catalyst has storage area, and this storage area can be realized the reversible storage to the sulphur in the lean exhaust gas.This by adopting " sulphur trap " adopts method of the present invention to carry out desulfurization to this trap termly, realized the catalyzer to postposition first, especially the protection of avoiding disadvantageous especially sulfur poisoning targetedly of NOx-storage catalyst.
Description of drawings
The present invention is described further will to contrast the embodiment shown in the accompanying drawing below.Shown in the figure:
Fig. 1 is the block diagram with internal-combustion engine of exhaust system;
Fig. 2 for burning λ and when the method according to this invention desulfurization at the time curve of measuring according to the downstream side of the pre-catalyst of Fig. 1;
Fig. 3 be according to the schematic block diagram of the internal-combustion engine of another embodiment exhaust system and
The characteristic curve that the oxygen of the time curve of the λ value of Fig. 4 motor, the tail gas λ that measures according to the downstream side of the downstream side of the pre-catalyst of Fig. 3 and primary catalyst and catalyzer according to the pre-catalyst desulfurization of the inventive method time the and primary catalyst loads.
Embodiment
The exhaust system that internal-combustion engine shown in Figure 1 10 is attached troops to a unit and had a usefulness 12 to indicate.Useful especially is that internal-combustion engine 10 is equipped with a not shown direct injection part, utilizes this direct injection partly by the high pressure fuel injector valve, and the fuel oil that flows to cylinder is by in the firing chamber of DCI direct cylinder injection.Preferably can carry out the vaporific oiling of layer to internal-combustion engine 10 in addition, wherein the fuel oil that sprays into when the vaporific work of layer is the time of ignition point concentrates on the scope of spark plug of cylinder substantially in layer mist mode in.When the vaporific work of layer, particularly form poor air fuel ratio, thereby can realize low especially oil consumption.Exhaust system 12 comprises an exhaust gas channel 14, wherein be provided with the pre-catalyst 16 of a little volume in position near motor, for example three-way catalyst, and the primary catalyst that is provided with a big volume in the position, chassis of automobile, especially a NOx-storage catalyst 18.Pre-catalyst 16 is equipped with the unshowned sulphur storage area 17 of its details in addition, and described sulphur storage area can store the exhaust gas component that contains sulphur at the poor working stage of internal-combustion engine 10.The known storage area 17 that is suitable for for example comprises barium salt.Wherein storage area 17 is blended in equally distributed mode in the catalysis constituent element of attached layer or as the catalyzer constituent element of separated by spaces.
When the poor work of internal-combustion engine 10, during the vaporific work of especially poor layer, the sulphur composition that contains at fuel oil is almost converted to sulfur dioxide SO fully
2SO
2Continue oxidized in the tail gas at oxygen enrichment on the catalytically inactive metalwork of pre-catalyst 16 and be stored in the component part of the storage area 17 of pre-catalyst 16 or other storage sulphur with 100% efficient almost with the form of sulphate.Inhale with the thiolysis of storage area 17 when assert that a pre-catalyst 16 temperature are approximate that temperature conforms to or when being about to reach thiolysis suction temperature, control unit 26 begins the desulfurization to pre-catalyst 16.
In Fig. 2 according to the process that the inventive method is shown with λ probe 20 burning λ that measure (curve 30) and the time curve that is positioned at the λ probe 22 tail gas λ that measure (curve 32) in pre-catalyst 16 downstream sides.At first internal-combustion engine 10 when the vaporific work of layer with poor burning λ work (or in case of necessity with the even working method of stoichiometry).The phase I τ that begins desulfurization with specific pre-process before inhaling temperature at the thiolysis that reaches pre-catalyst 16
1And internal-combustion engine 10 is with the first enriched combustion λ λ
F1Work, described λ
F1Preferably between 0.8 to 0.9, the tail gas λ in pre-catalyst 16 downstream sides after internal-combustion engine 10 conversions will sharply reduce and remain on λ=1 in the regular hour.Before the oxygen storage of pre-catalyst 16 is drained, the reducing agent (HC, CO) that exists in rich exhaust gas in this stage will be fallen by full consumption.Just begin to pass pre-catalyst at rich exhaust gas after this, be reduced to numerical value＜1 thereby make λ probe 22 detect more and more richer tail gas and tail gas λ 32.When the gas transducer 24 that is positioned at NOx-storage catalyst 18 downstream sides is measured the tail gas of same richness, phase I τ
1Finish (pre-process is not shown).Therefore guaranteed that the whole antigravity system of punctum does not contain or do not contain fully aerobic at least to a great extent at this moment.
The second stage τ that is following
2, wherein pre-catalyst 16 has at least reached minimum thiolysis and has inhaled temperature, thereby realizes the discharge of intrinsic sulphur, and internal-combustion engine 10 is alternately with poor burning λ
MWith the second enriched combustion λ
F2Work.At the first poor interval τ
MIn, to poor burning λ
MAdjust described poor burning λ
MShould be between 1.01 to 1.2, preferably between 1.04 to 1.08, so that realize the storage of certain oxygen on pre-catalyst 16.Therefore the tail gas λ 32 that measures in pre-catalyst 16 downstream sides begins to increase and approach predetermined threshold value S
M, described threshold value is at λ=1.0 and λ
MBetween.22 tail gas λ that measures and the threshold value S in case λ pops one's head in
MConform to, then to be switched to its second enriched combustion λ be λ to internal-combustion engine 10
F2Rich S at interval
M, described rich S at interval
MShould be between 0.93 to 0.995, preferably between 0.97 to 0.99.Therefore the tail gas λ 32 in pre-catalyst 16 downstream sides reduces again and remains on λ=1 again in the regular hour.Utilize the reducing agent that exists in tail gas to be stored in sulphur on the sulphur storage area 17 in this is reduced and discharges in stage.Wherein pass through poor interval τ formerly
MIn the oxygen that stores guaranteed reduction remain on the oxidation valency of sulfur dioxide (+IV) go up and not exclusively be transformed into hydrogen sulfide H
2S (valency II).At first pass through poor interval τ
MThreshold value S during this time
MThe predetermined suitable for this reason degree that the oxygen of pre-catalyst 16 is loaded adjust.From richness interval τ
MThe reducing agent that begins in the tail gas of a specified point no longer fully be used to change sulphate, thereby tail gas λ 32 progressively is reduced to rich λ value＜1.In case tail gas λ 32 reaches the second threshold value SF, described second threshold value is at λ=1.0 and λ
F2Between, internal-combustion engine 10 is again with poor burning λ λ
MWork.Then under similarly controlling, carry out other poor and rich τ at interval
M, τ
F
Though at second stage τ
2By the SO that discharges in the pre-catalyst 16
2Arrive rearmounted NOx-storage catalyst, but the SO that discharges
2Can not store and pass rearmounted NOx-storage catalyst.Sulphur at first needs SO with the storage of form on the NOx-storage catalyst of sulphate
2Be oxidized to SO
3And thereby need the existence of oxygen.Because at phase I τ
1The oxygen storage of NOx-storage catalyst 18 is drained and even the rich τ at interval that following
MAlmost do not have oxygen to arrive on the storage catalyst 18, thereby do not have oxygen.
The method according to this invention has realized nearly all with SO
2Form is stored in the release of the sulphur on the pre-catalyst 16, and can not cause then sulphur being stored in again to this on responsive especially NOx-storage catalyst 18.Therefore must carry out desulfurization to NOx-storage catalyst 18 with the bigger time lag, and this desulfurization will cause the increase of oil consumption, this is because this desulfurization needs very high catalyst temperature, this catalyst temperature must be a cost with continuous reduction engine efficiency again, therefore certainly will cause obviously high oil consumption.In addition because at second stage τ
2Intermittence poor-/rich the loading almost can be fully to having overpowering odor and harmful H
2The generation of S and discharging suppress and simultaneously passing of reducing agent HC and CO are remained on faint degree.So feature overall of the present invention is to have realized faint especially emission of harmful substances.This method of the present invention has been realized the design targetedly to pre-catalyst of conduct " sulphur trap ".Thereby NOx-storage catalyst 18 almost completely can be avoided sulfur poisoning and in fact can save storage catalyst 18 otherwise with the desulfurization of needs.
Internal-combustion engine shown in Figure 3 10 attached troops to a unit whole exhaust systems with 12 signs.What internal-combustion engine 10 was useful especially is to be equipped with the direct injection device, adopts this direct injection device will remain to be joined in the fuel oil DCI direct cylinder injection firing chamber in the cylinder by a high pressure fuel injector valve.In addition preferably can the vaporific loading of layer to internal-combustion engine 10, wherein the fuel oil that sprays into when the vaporific oiling of layer work concentrates in the spark plug scope of cylinder with layer oiling mist form substantially in a moment point.When the vaporific oiling of layer worked, constitute poor especially sky combustion mixed gas, thereby can realize low oil consumption.
When the poor work of internal-combustion engine 10, when the vaporific oiling of especially poor layer worked, the sulphur composition that contains at fuel oil was almost converted to sulfur dioxide SO fully
2SO
2Continue oxidized in the tail gas at oxygen enrichment on the catalytically inactive metalwork of pre-catalyst 16 and be stored in the component part of the storage area 17 of pre-catalyst 16 or other storage sulphur with 100% efficient almost with the form of sulphate.Inhale with the thiolysis of storage area 17 when assert that a pre-catalyst 16 temperature are approximate that temperature conforms to or when being about to reach thiolysis suction temperature, control unit 26 begins pre-catalyst 16 desulfurization.
In Fig. 4 according to the λ probe 22 burning λ that measure
Mot(motor λ) and (with still unmeasured) the tail gas λ that is arranged in pre-catalyst 16 downstream sides in enforcement this method process
NHKTime curve the control of the inventive method is shown.The intermediate portion of Fig. 4 illustrates the oxygen loading O of the reality of pre-catalyst 19 in addition
VKThe oxygen that NOx-storage catalyst 18 is shown with lower part loads O
VkProcess.
At first internal-combustion engine 10 when the vaporific oiling of layer work with poor burning λ work (or in case of necessity with the even working method of stoichiometry).The phase I T that begins desulfurization with specific pre-process before inhaling temperature at the thiolysis that reaches pre-catalyst 16
1And internal-combustion engine 10 with the first enriched combustion λ λ
F1The motor λ λ that conforms to
MotWork, described λ
F1Preferred (time point t between 0.8 to 0.9
0).
Be transformed into λ at internal-combustion engine 10
F1After begin that and then pre-catalyst 16 is carried out oxygen and load, from the oxygen storage capacity OSC that conforms to the maximum load position of pre-catalyst 16
VKBeginning.At the oxygen of this storage in stage for the reducing agent HC in the tail gas, CO oxidation are used up fully.In case the oxygen storage of pre-catalyst 16 is drained O
VK=0, then rich exhaust gas passes pre-catalyst 16 first, thereby makes the tail gas λ λ in pre-catalyst 16 downstream sides
NVKReduce, be lower than λ=1.Therefore the oxygen storage of NOx-storage catalyst 18 also begins emptying and its actual O
2-loading O
HKBe reduced to 0 equally.Just detect λ in NOx-storage catalyst 18 downstream sides then
NHKIn case be positioned at the tail gas λ that the gas transducer 24 in NOx-storage catalyst 18 downstream sides is measured
NHK(time point t when being lower than the first rich threshold value
1), phase I T
1Finish.Therefore guaranteed that the whole antigravity system of punctum does not contain aerobic at least to a great extent or fully at this moment, especially the oxygen of NOx-storage catalyst 18 loads O
HKBe up to 20%, especially be lower than its maximum oxygen storage capacity OSC
HK10%.Wherein at the transit time of considering the tail gas between internal-combustion engine 10 and NOx-storage catalyst 18, S
F1Design should make at time point t
1The lean exhaust gas that last conversion back exists arrives the NOx-storage catalyst 18 that does not contain aerobic fully.
The second stage T that is following
2, wherein pre-catalyst 16 has at least reached minimum thiolysis and has inhaled temperature, thereby realizes the discharge of intrinsic sulphur, and internal-combustion engine 10 is alternately with richness interval τ
FWith poor interval τ
MWork.At the first poor interval τ
MIn, with engine combustion λ
MotAdjust to poor burning λ
M, described poor burning λ
MShould be between 1.0 to 1.2, preferably between 1.02 to 1.04, so that realize the storage of certain oxygen on pre-catalyst 16.Therefore the oxygen on pre-catalyst 16 loads O
VKIncrease beginning and at the tail gas λ of pre-catalyst 16 back
NVKHaving certain hysteresis also begins to increase.Pass pre-catalyst 16 back (λ at oxygen
NVK＞1) just begin to the oxygen storage of NOx-storage catalyst 18 pack into lentamente oxygen and thereby O
HKRealize weak increase.The tail gas λ that behind NOx-storage catalyst 18, measures simultaneously
NVKAlso behind a fixed response time, increase.
At λ
NVKBefore beginning to increase, internal-combustion engine 10 is at time point t
2Being switched to its second enriched combustion λ is λ
F2Rich τ at interval
M, described rich S at interval
MShould be between 0.93 to 0.995, preferably between 0.97 to 0.99.Therefore the oxygen of pre-catalyst 16 loads O
VKTo reduce.Utilize the reducing agent that exists in tail gas to be stored in sulphur on the sulphur storage area 17 in this is reduced and discharges in stage.Wherein pass through poor interval τ formerly
MIn the oxygen that stores guaranteed reduction, make reduction remain on sulfur dioxide the oxidation valency (+IV) go up and not exclusively convert to hydrogen sulfide H
2S (valency II).From richness interval τ
FThe reducing agent that begins in the tail gas of a specified point no longer fully be used to change sulphate, thereby at the tail gas λ of pre-catalyst 16 λ
NVKProgressively be reduced to rich λ value＜1, thereby impel NOx-storage catalyst 18 (O
HKThe emptying of oxygen storage reduction).
Though at second stage T
2, exactly at richness interval τ
FBy the SO that discharges in the pre-catalyst 16
2Arrive rearmounted NOx-storage catalyst, but the SO that discharges
2Can not store and pass rearmounted NOx-storage catalyst.Sulphur at first needs SO with the storage of form on the NOx-storage catalyst of sulphate
2Be oxidized to SO
3And thereby need the existence of oxygen.Because at phase I T
1The oxygen storage of NOx-storage catalyst 18 is drained and even is following at second stage T
2Poor interval τ
MAlmost there is not oxygen to arrive storage catalyst 18, so do not have oxygen for using.
At least at second stage T
2Beginning is preceding to poor interval τ
MWith richness interval τ
FTime span control at first in advance, wherein according to the real work parameter of internal-combustion engine 10, for example the load of motor or rotating speed are scheduled to the pre-control value of storage.The pre-control value especially depends on the oxygen storage capacity OSC of pre-catalyst 16
VKAnd for example can conform to the actual storage capacity that the fresh situation or of catalyzer 16 is determined in desulfurization formerly.Wherein poor interval τ
MTime span determine should make poor interval τ
MEnd overlap with poor passing as far as possible accurately pre-catalyst 16.Adopt this mode only to have a spot of oxygen can arrive NOx-storage catalyst 18, thereby have only the oxygen of trace to be stored on the NOx-storage catalyst 18.Rich τ at interval
FThe pre-control value determine should make the reality emptying completely that realizes the oxygen storage of NOx-storage catalyst 18 in the transit time of considering tail gas.
By with internal-combustion engine 10 from poor interval τ
MConvert rich τ at interval to
F(for example at time point t
2On) realize poor interval τ
MWith richness interval τ
FThe check of pre-control value of storage of time span and adaptive adjustment in case of necessity.Then to changing the back until tail gas λ in NOx-storage catalyst 18 back
NHKBe lower than predetermined first rich threshold value SF
1The time delay of (on lower λ value direction) is measured.Wherein under the situation of considering the tail gas transit time to S
F1Design should guarantee that the oxygen storage of pre-catalyst 16 is emptied completely by actual.The time delay of measuring in this hypothesis is greater than richness τ at interval
FThe pre-control value so far of time span is then implemented adaptive adjustment, wherein with the rich τ at interval in future
FShorten a fixing or variable difference.Otherwise, when the time delay of measuring is shorter than rich τ at interval
FTime span so far (must not be lower than S when this situation
F1), then follow-up interval S
F1Prolong a difference.
For the minimizing to the aging of catalyzer and oxygen storage capacity thereupon takes in, at second stage T
2In the process and/or at phase I T
1During end to the oxygen storage capacity OSC of whole antigravity system 16,18
∑Determined.For this reason at second stage T
2In carry out a poor interval τ who prolongs
M, its length is until the tail gas λ in storage catalyst 18 back
NHKReach predetermined poor threshold value S
MWherein poor threshold value S
MDesign should make conforming to surpassing of its with 100% oxygen loading of NOx-storage catalyst 18 and whole antigravity system thereupon.In fact work as λ
NHKSurpass the second rich threshold value S
F2The time will finish the poor interval τ that prolongs
MAnd carry out internal-combustion engine to λ
F2Conversion.Therefore can use the tail gas transit time to poor threshold value S
MRevise, so that avoid too much oxygen to join in the storage catalyst 18.By measuring the poor interval τ that motor begins to prolong
MCan obtain as storage capacity summation (OSC the time delay between poor the passing of NOx-storage catalyst 18 to measuring with gas transducer
VK+ OSC
HK) oxygen storage capacity OSC
∑According to known OSC
ΣAnd the ratio of the oxygen storage capacity between one in the fresh catalyzer 16,18 can be determined the maximum oxygen storage capacity OSC of pre-catalyst 16
VKOSC according to the pre-catalyst of obtaining 16
VKCan be to poor interval τ
MWith richness interval τ
FRevised.Can realize λ threshold value S equally
M, S
F1And S
F2Adaptive adjustment.
Particularly preferably be at phase I T
1The tail gas that carries out that replaces during end loads preceding oxygen storage capacity OSC to whole antigravity system 16,18
∑Determine (not shown).Preferably for this reason at first inhale the slightly poor tail gas loading that is used under the temperature 20K situation between 1.005 and 1.05, until behind storage catalyst 18, detecting λ at the minimum thiolysis of the pre-catalyst 16 of catalysis system
NHKDetection step to " poor " direction.If this kind situation then exists the oxygen of the maximum of catalysis system 16,18 to load.Then between 0.95 to 0.995, omit rich tail gas to system loads, until the detection step that detects in storage catalyst 18 downstream sides to the gas transducer 24 of " richness " direction with the λ value.Adopt this mode to detect the time delay that the richness in NOx-storage catalyst 18 downstream sides passes to being transformed into of richness and analyze from poor, so that obtain whole oxygen storage capacity OSC by motor λ
∑The advantage of this mode is, along with second stage T
2Beginning can be with richness τ at interval
FWith poor interval τ
MTime span adaptive with the actual catalyst situation of actual catalyst behavior, especially pre-catalyst 16.
Though the pre-catalyst of realizing with useful especially employing sulphur storage area 17 16 this method is illustrated the present invention is not limited to this for example.Method of the present invention equally also is applicable to the common pre-catalyst system with sulphur collecting function.
Realized nearly all with SO
2The sulphur that form is stored on the pre-catalyst 16 is released, and can not cause then sulphur being stored in again to this on responsive especially NOx-storage catalyst 18.Therefore the desulfurization to NOx-storage catalyst 18 with the special oil consumption of carrying out than large-spacing is necessary, and this desulfurization promptly needs to reduce the measure of engine efficiency all the time and therefore will cause obviously high oil consumption owing to need very high catalyst temperature for this reason.In addition because at second stage τ
2Intermittence poor-/rich the loading almost can be fully to having overpowering odor and harmful H
2The generation of S and discharging suppress and simultaneously passing of reducing agent HC and CO are remained on faint degree.So feature overall of the present invention is to have realized faint especially emission of harmful substances.This method of the present invention has been realized the design targetedly to pre-catalyst of conduct " sulphur trap ".Thereby NOx-storage catalyst 18 almost completely can be avoided sulfur poisoning and in fact can save storage catalyst 18 otherwise with the desulfurization of needs.
The Reference numeral table of comparisons
10 internal combustion engines
12 exhaust systems
14 exhaust gas channels
16 pre-catalysts
17 sulphur-storage compartment
The catalyzer of 18 postposition/NOx-storage catalyst
20,22 oxysensible measuring devices/λ probe
24 oxysensible measuring devices/NOx-sensor device
26 control units
28 control unit of engine
30 burning λ values
The tail gas λ value in 32 pre-catalyst downstream sides
λ air fuel ratio λ
λ
F1The first enriched combustion λ
λ
F2The second enriched combustion λ
λ
MPoor burning λ
τ
FAt interval rich
τ
MPoor interval
τ
M 'The poor interval that prolongs
λ
MotBurning λ value/motor λ value
λ
NHKThe tail gas λ value in NOx-storage catalyst downstream side
λ
NVKThe tail gas λ value in prestor catalyzer downstream side
O
HKThe oxygen of NOx-storage catalyst absorbs
OSC
∑The oxygen storage capacity of whole antigravity system
OSC
HKThe oxygen storage capacity of NOx-storage catalyst
OSC
VKThe oxygen storage capacity of pre-catalyst
O
VKThe oxygen of pre-catalyst absorbs
S
FSecond threshold value
S
F1The first rich threshold value
S
F2The second rich threshold value
S
MFirst threshold
S
MPoor threshold value
The t time
T
1, τ
1Phase I (deoxidation)
T
2, τ
2Second stage (desulfurization)
Claims (69)
1. one kind is used for being arranged on the method for pre-catalyst (16) desulfurization in internal-combustion engine (10) exhaust gas channel (14) at least, behind this pre-catalyst, be connected to another catalyzer (18) at least, it is characterized in that, when reaching pre-catalyst (16) temperature or reaching in the pre-process before pre-catalyst (16) temperature, described pre-catalyst temperature equals the minimum thiolysis of pre-catalyst temperature (16) at least and inhales temperature
(a) at phase I (τ
1) internal-combustion engine (10) is with the first enriched combustion λ (λ
F1) work, until the oxygen storage of the catalyzer (18) of postposition realize at least to a great extent not having oxygen degree and
(b) second stage (τ that is following
2) internal-combustion engine (10) alternately has poor burning λ (λ
M) poor interval (τ
M) and have the second enriched combustion λ (λ
F2) rich (τ at interval
F) work.
2. in accordance with the method for claim 1, it is characterized in that second stage (τ
2) poor interval (τ
M) and rich (τ at interval
F) determine should be able to discharge mainly with sulfur dioxide (SO
2) form be stored in sulphur in the pre-catalyst (16).
4. in accordance with the method for claim 3, it is characterized in that, adopt an oxysensible measuring device (22) that the tail gas λ in pre-catalyst (16) downstream side is measured.
5. according to the method for claim 4, it is characterized in that employing λ probe is measured the tail gas λ in pre-catalyst (16) downstream side.
6. in accordance with the method for claim 3, it is characterized in that first threshold (S
M) be 1.0 and poor burning λ (λ
M) between the λ value and second threshold value be at the 1.0 and second enriched combustion λ (λ
F2) between the λ value.
7. in accordance with the method for claim 1, it is characterized in that, at second stage (τ
2) interior to richness interval (τ
F) and poor interval (τ
M) between timing controlled ground change.
8. in accordance with the method for claim 7, it is characterized in that rich (τ at interval
F) time span be 1 to 20 second and poor interval (τ
M) time span be 0.5 to 10 second.
9. in accordance with the method for claim 8, it is characterized in that rich (τ at interval
F) time span be 2 to 10 seconds and poor interval (τ
M) time span be 2 to 6 seconds.
10. in accordance with the method for claim 7, it is characterized in that, in a single day measure lean exhaust gas λ at the latest, then at second stage (τ in catalyzer (18) downstream of postposition
2) in carry out by poor interval (τ
M) to richness interval (τ
F) conversion.
11., it is characterized in that rich (τ at interval according to claim 1 or 2 described methods
F) the second enriched combustion λ (λ
F2) be 0.93 to 0.995.
12. in accordance with the method for claim 11, it is characterized in that rich (τ at interval
F) the second enriched combustion λ (λ
F2) be 0.97 to 0.99.
13., it is characterized in that second stage (τ according to claim 1 or 2 described methods
2) poor burning λ (λ
M) be 1.01 to 1.2.
14. in accordance with the method for claim 13, it is characterized in that second stage (τ
2) poor burning λ (λ
M) be 1.04 to 1.08.
15. according to claim 1 or 2 described methods, it is characterized in that, the oxygen storage capacity of the catalyzer (18) of postposition the most nearly 20% occupied before, will keep the phase I (τ
1).
16. in accordance with the method for claim 15, it is characterized in that, the catalyzer (18) of postposition be not more than 10% oxygen storage capacity occupied before, will keep the phase I (τ
1).
17. in accordance with the method for claim 15, it is characterized in that, utilize the oxysensible measuring device (24) be placed on rearmounted catalyzer (18) that the emptying at least to a great extent of the oxygen storage of the catalyzer (18) of postposition is monitored.
18., it is characterized in that phase I (τ according to claim 1 or 2 described methods
1) the first enriched combustion λ (λ
F1) be 0.7 to 0.95.
19. in accordance with the method for claim 18, it is characterized in that phase I (τ
1) the first enriched combustion λ (λ
F1) be 0.8 to 0.9.
20. according to claim 1 or 2 described methods, it is characterized in that, before pre-catalyst (16) is desulfurized at least to a great extent, keep second stage (τ always
2).
21. according to claim 1 or 2 described methods, it is characterized in that, determine second stage (τ according to the modeled sulphur loading of pre-catalyst (16)
2) end.
22. in accordance with the method for claim 21, it is characterized in that, obtain sulphur according to the adding of the sulphur of the modeled pre-catalyst of a contrast internal-combustion engine (10) actual work temperature (16) and/or discharge and load.
23. according to claim 1 or 2 described methods, it is characterized in that, to the temperature that the temperature of pre-catalyst (16) is measured or pre-catalyst (16) are obtained in calculating according to model.
24. according to claim 1 or 2 described methods, it is characterized in that, to the temperature of predetermined periods prediction pre-catalyst, and when in the period, will reach thiolysis suction temperature through prediction identification, before pre-catalyst (16) does not reach thiolysis suction temperature as yet, beginning phase I (τ
1).
25. in accordance with the method for claim 24, it is characterized in that, consider the pedal value generator of gas pedal position, pedal value generator dynamically, the true temperature of the rotating speed of motor, the amount of fuel that sprays into, pre-catalyst, pre-catalyst temperature dynamically, the modeled sulphur of pre-catalyst (16) adds and the oxygen of pre-catalyst (16) stores activity the temperature of pre-catalyst is predicted.
26. according to claim 1 or 2 described methods, it is characterized in that, according to the position of the pedal value generator of gas pedal, pedal value generator dynamically, the true temperature of the rotating speed of motor, the amount of fuel that sprays into, pre-catalyst, pre-catalyst temperature dynamically, the modeled sulphur of pre-catalyst (16) adds and the oxygen of pre-catalyst (16) stores the activity of conversion of the temperature of active, rearmounted catalyzer (18) and/or temperature dynamic, rearmounted catalyzer (18) and/or the oxygen of rearmounted catalyzer (18) stores activity to the first enriched combustion λ (λ
F1), the second enriched combustion λ (λ
F2), poor burning λ (λ
M), first threshold (S
M) and/or the second threshold value (S
F) be scheduled to.
27., it is characterized in that the desulfurization of pre-catalyst (16) is overlapping or and then carry out with the NOx-regeneration of the NOx-storage catalyst of postposition at least in part according to claim 1 or 2 described methods.
28., it is characterized in that the displacement during to pre-catalyst (16) desulfurization is interrupted suppressing according to claim 1 or 2 described methods.
29. in accordance with the method for claim 1, it is characterized in that, as follows to poor interval (τ
M) and/or rich (τ at interval
F) carry out timing mensuration, promptly have 25% at least with sulfur dioxide (SO
2) sulphur that is stored in the pre-catalyst (16) of mode is discharged from.
30. in accordance with the method for claim 29, it is characterized in that, at second stage (T
2) at least the first interior poor interval (τ
M) and/or at least the first rich (τ at interval
F) time, predetermined variable pre-control value.
31. in accordance with the method for claim 30, it is characterized in that, according to the oxygen storage capacity (OSC of the oxygen storage of pre-catalyst (16)
VK) determine the pre-control value.
32. according to the described method of claim 31, it is characterized in that, according to the oxygen storage capacity (OSC of whole antigravity system (16,18)
∑) and according to the oxygen storage capacity (OSC of pre-catalyst (16)
VK) with the oxygen storage capacity (OSC of rearmounted at least catalyzer (18)
HK) ratio obtain the oxygen storage capacity (OSC of pre-catalyst (16)
VK).
33. in accordance with the method for claim 30, it is characterized in that the pre-control value is stored in the characteristic curve relevant with the operation point.
34. according to the described method of claim 31, it is characterized in that, at second stage (T
2) poor interval (τ
M) time span determine should make at poor interval (τ
M) interior oxygen storage volume (OSC to one of them pre-catalyst (16)
VK) at least 30% and maximum 99% be filled.
35. according to the described method of claim 34, it is characterized in that, at second stage (T
2) poor interval (τ
M) time span determine should make at poor interval (τ
M) interior oxygen storage volume (OSC to one of them pre-catalyst (16)
VK) at least 50% and maximum 95% be filled.
36. according to the described method of claim 34, it is characterized in that, to poor interval (τ
M) time span determine should make poor interval (τ
M) end conform to a time point at the latest, lean exhaust gas passes pre-catalyst (16) on this time point.
37. in accordance with the method for claim 29, it is characterized in that, in second stage to richness (τ at interval
F) time span determine should make at richness (τ at interval
F) in mainly with sulfur dioxide (SO
2) the mode sulphur that is stored in pre-catalyst (16) is discharged from.
38. according to the described method of claim 37, it is characterized in that, to richness interval (τ
F) time span determine should make rich (τ at interval
F) end conform to the oxygen storage (OSC of pre-catalyst on this time point basically at the latest with a time point
VK) do not contain aerobic to a great extent.
39. according to the described method of claim 32, it is characterized in that, according to one at internal-combustion engine (10) by a poor mode of operation to the oxygen storage volume (OSC that determines whole antigravity system (16,18) after the rich working mode change first in the detected downstream of the catalyzer (18) of postposition to the institute's elapsed time section in the antigravity system that actual maximum oxygen stores before the rich exhaust gas
∑).
40. according to the described method of claim 39, it is characterized in that, before second stage (T2) beginning, carry out oxygen storage volume (OSC to antigravity system (16,18)
∑) determine.
41. according to the described method of claim 40, it is characterized in that, at phase I (T
1) carry out oxygen storage volume (OSC when finishing to antigravity system (16,18)
∑) determine.
42. according to the described method of claim 39, it is characterized in that, before the minimum thiolysis that reaches pre-catalyst (16) is inhaled temperature to the oxygen storage volume (OSC of pre-catalyst system (16,18)
∑) determined.
43. according to the described method of claim 42, it is characterized in that, when the minimum thiolysis that is lower than pre-catalyst (16) is inhaled temperature 20K to the oxygen storage volume (OSC of pre-catalyst system (16,18)
∑) determined.
44. according to the described method of claim 32, it is characterized in that, determine the oxygen storage volume (OSC of antigravity system (16,18) according to the time period
∑), the described time period is to detect lean exhaust gas at least in the downstream side of the catalyzer (18) of postposition first or surpass predetermined poor threshold value (S after internal-combustion engine (10) becomes poor working mode change by rich working mode change
M) preceding at least in the time of antigravity system (16,18) near anaerobic.
45. according to the described method of claim 44, it is characterized in that, to predetermined poor threshold value (S
M) design should make by the oxygen storage (OSC that at least almost completely is full of catalyzer (18) at least one postposition
HK) the tail gas λ (λ in catalyzer (18) downstream
NHK) and surpass poor threshold value (S
M) time point relevant.
46. according to the described method of claim 44, it is characterized in that, at second stage (T
2) carry out oxygen storage volume (OSC
∑) determine.
47. in accordance with the method for claim 29, it is characterized in that, at second stage (T
2) according to the internal-combustion engine (10) measured from richness (τ at interval
F) to poor interval (τ
M) conversion until being lower than the first predetermined rich threshold value (S
F1) the tail gas λ (λ that successively decreases by the downstream of at least one rearmounted catalyzer of time period
NHK) to richness value direction to richness (τ at interval
F) the pre-control value of time span carries out adaptive.
48. the first rich threshold value (S that is scheduled in accordance with the method for claim 29,
F1) design should make the oxygen storage (OSC of primary catalyst (18) at least one postposition
HK) the tail gas λ (λ in downstream of catalyzer (18) of at least almost emptying
NHK) relevant with the time point that is lower than this threshold value.
49. in accordance with the method for claim 29, it is characterized in that, adopt an oxysensible measuring device (22), especially adopt a NOx-sensor or λ probe that the tail gas λ in catalyzer (18) downstream of at least one postposition is measured.
50. in accordance with the method for claim 29, it is characterized in that second stage (T
2) rich (τ at interval
F) the second enriched combustion λ (λ
F) be 0.93 to 0.995.
51., it is characterized in that second stage (T according to the described method of claim 50
2) rich (τ at interval
F) the second enriched combustion λ (λ
F) be 0.97 to 0.99.
52. in accordance with the method for claim 29, it is characterized in that second stage (T
2) poor interval (τ
M) the second poor burning λ (λ
M) be 1.0 to 1.2.
53., it is characterized in that second stage (T according to the described method of claim 52
2) poor interval (τ
M) the second poor burning λ (λ
M) be 1.02 to 1.04.
54. in accordance with the method for claim 29, it is characterized in that phase I 41 (T
1) the first enriched combustion λ (λ
F1) be 0.7 to 0.95.
55., it is characterized in that phase I 41 (T according to the described method of claim 54
1) the first enriched combustion λ (λ
F1) be 0.8 to 0.9.
56. in accordance with the method for claim 29, it is characterized in that, at the oxygen storage volume (OSC of the catalyzer (18) of at least one postposition
HK) be up to 20% and keep phase I (T before occupied
1).
57. according to the described method of claim 56, it is characterized in that, at 10% the oxygen storage volume (OSC of being less than of the catalyzer (18) of at least one postposition
HK) the occupied preceding phase I (T that keeps
1).
58. in accordance with the method for claim 29, it is characterized in that, remain on the second (T before the desulfurization at least to a great extent at pre-catalyst (16)
2) stage.
59. according to the described method of claim 58, it is characterized in that, determine second stage (T according to the adding of the modeled sulphur of pre-catalyst (16)
2) end.
60. according to the described method of claim 59, it is characterized in that, according to the loading of obtaining sulphur according to the discharge of the adding of the sulphur of the real work parameter modelization of the pre-catalyst (16) of internal-combustion engine (10) and/or sulphur.
61. in accordance with the method for claim 29, it is characterized in that, to the temperature that the temperature of pre-catalyst (16) is measured or pre-catalyst (16) are obtained in calculating according to model.
62. in accordance with the method for claim 29, it is characterized in that, to preset time section prediction pre-catalyst (16) if temperature and in the time period, will reach thiolysis by prediction identification and inhale temperature, then reach before thiolysis inhales temperature beginning phase I (T at pre-catalyst (16)
1).
63. according to the described method of claim 62, it is characterized in that, consider the pedal value generator of gas pedal position, pedal value generator dynamically, the true temperature of the rotating speed of motor, the amount of fuel that sprays into, pre-catalyst, pre-catalyst temperature dynamically, the modeled sulphur of pre-catalyst (16) loads and/or the oxygen of pre-catalyst (16) stores the active prediction of carrying out pre-catalyst.
64. in accordance with the method for claim 29, it is characterized in that the desulfurization of pre-catalyst (16) is overlapping or and then carry out with the NOx-regeneration of the NOx-storage catalyst (18) of postposition at least in part.
65. in accordance with the method for claim 29, it is characterized in that, the displacement in during the desulfurization of pre-catalyst (16) is interrupted suppressing.
66. be used at least one is arranged on the device that the pre-catalyst (16) that is provided with in the exhaust gas channel (14) of the internal-combustion engine (10) that can move in poor mode carries out desulfurization, at least be provided with another catalyzer (18) in this pre-catalyst back, employing one is arranged on the oxysensible gas transducer (22) and the mechanism in the downstream side of pre-catalyst (16), utilize this gas transducer and mechanism when reaching pre-catalyst (16) temperature or reaching in the pre-process before pre-catalyst (16) temperature, described pre-catalyst temperature is greater than or equal to the minimum thiolysis of pre-catalyst temperature (16) and inhales temperature, carries out following method step:
(a) at phase I (τ
1) internal-combustion engine (10) is with the first enriched combustion λ (λ
F1) work, until the oxygen storage of the catalyzer (18) of postposition realize at least to a great extent not having oxygen degree and
(b) second stage (τ that is following
2) internal-combustion engine (10) alternately has poor burning λ (λ
M) poor interval (τ
M) and have the second enriched combustion λ value (λ
F2) rich (τ at interval
F) work.
67. be used at least one is arranged on the device that the pre-catalyst (16) in the exhaust gas channel (14) of the internal-combustion engine (10) that can move in poor mode carries out desulfurization, at least be provided with another catalyzer (18) in this pre-catalyst back, employing one is arranged on the oxysensible gas transducer (22) and the mechanism in the downstream side of pre-catalyst (16), utilize this gas transducer and device when reaching pre-catalyst (16) temperature or reaching in the pre-process before pre-catalyst (16) temperature, described pre-catalyst temperature is greater than or equal to the minimum thiolysis of pre-catalyst temperature (16) and inhales temperature, carries out following method step:
(a) at phase I (T
1) internal-combustion engine (10) is with the first enriched combustion λ (λ
F1) work, until the oxygen storage of the catalyzer (18) of postposition realize at least to a great extent not containing aerobic degree and
(b) second stage (T that is following
2) internal-combustion engine (10) alternately has poor burning λ (λ
M) poor interval (τ
M) and have the second enriched combustion λ (λ
F2) rich (τ at interval
F) work, wherein to poor interval (τ
M) and/or rich (τ at interval
F) time-controlledly determine should to make at least 25% with sulfur dioxide (SO
2) sulphur that is stored in the pre-catalyst (16) of form is discharged from.
68., it is characterized in that pre-catalyst (16) is equipped with sulphur storage area (17) according to claim 66 or 67 described devices, described sulphur storage area is used for the sulphur of lean exhaust gas is carried out reversible storage.
69., it is characterized in that described device comprises a control unit (26) according to claim 66 or 67 described devices, in this control unit, be useful on the algorithm of implementation methods with digital store.
70., it is characterized in that control unit (26) strikes up partnership with control unit of engine (28) according to the described device of claim 69.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2001123148 DE10123148B4 (en) | 2001-05-03 | 2001-05-03 | Method and device for desulfurization of a precatalyst |
| DE10123148.2 | 2001-05-03 | ||
| DE10202935A DE10202935A1 (en) | 2002-01-14 | 2002-01-14 | Operating process for removal of sulfur deposits from the pre-catalyst in an IC engine exhaust system by periodic inducing of high temperature with alternating lean and rich lambda conditions |
| DE10202935.0 | 2002-01-14 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1384277A CN1384277A (en) | 2002-12-11 |
| CN1271319C true CN1271319C (en) | 2006-08-23 |
Family
ID=26009278
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 02119321 Expired - Fee Related CN1271319C (en) | 2001-05-03 | 2002-05-08 | Method and apparatus for desulfurizing pre-catalyst |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1271319C (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008138522A (en) * | 2006-11-30 | 2008-06-19 | Hitachi Ltd | Method of early warming up catalyst during engine starting, and fuel control device provided with the method |
| JP4802116B2 (en) * | 2007-02-21 | 2011-10-26 | 日本特殊陶業株式会社 | Gas sensor abnormality diagnosis method, gas sensor abnormality diagnosis device |
| JP6597683B2 (en) * | 2017-03-16 | 2019-10-30 | トヨタ自動車株式会社 | Control device for internal combustion engine |
| CN110700955B (en) * | 2018-12-28 | 2020-12-08 | 长城汽车股份有限公司 | Method and device for controlling excess air coefficient of gasoline engine catalyst |
-
2002
- 2002-05-08 CN CN 02119321 patent/CN1271319C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1384277A (en) | 2002-12-11 |
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