• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to a method of supplying additives to a catalytic exhaust gas purification process for purifying an exhaust gas stream from a single-combustion engine of a vehicle, said vehicle comprising control means for controlling the supply of said additive to said exhaust gas stream. The method comprises certifying an expected temperature ratio for said exhaust gas purification process with the aid of a representation of the vehicle base, and controlling said supply additive based on said estimated temperature ratio. Fig. 5
    公开号:SE1050395A1
    申请号:SE1050395
    申请日:2010-04-21
    公开日:2011-10-22
    发明作者:Mikael Lundstroem
    申请人:Scania Cv Ab；
    IPC主号:
    专利说明:

    nitrous oxide and nitrogen dioxide, respectively), heavy vehicles often comprise a catalyst in which an additive is added to the exhaust gas stream resulting from the combustion engine combustion in order to reduce nitrogen oxides NOX (to mainly nitrogen gas and water vapor).
    A common type of catalyst, especially for heavy vehicles, are SCR (Selective Catalyst Reduction) catalysts. SCR catalysts use ammonia (NH3), or a composition from which ammonia can be generated / formed, as an additive to reduce the amount of nitrogen oxides NOX.
    The additive is injected into the exhaust gas stream resulting from the internal combustion engine upstream of the catalyst.
    The ratio between emissions of nitrogen oxides NOX from an internal combustion engine and the fuel consumption of the internal combustion engine is inversely proportional. This means that if the internal combustion engine is set to work with higher efficiency (efficiency is affected by eg injection angle / time and fuel / air mixture), and thus a lower fuel consumption, which is desirable from an economic point of view, the combustion process results in higher emissions of nitrogen oxides, which in turn places higher demands on subsequent exhaust gas purification.
    The additive fed to the catalyst is adsorbed (stored) in the catalyst, whereby nitrogen oxides in the exhaust gases react with the ammonia stored in the catalyst.
    However, the ability of the catalyst to store additives usually varies greatly with the temperature prevailing in the catalyst. At lower temperatures, larger amounts of ammonia can be stored, while the storage capacity at higher temperatures is lower.
    A sudden rise in temperature in the catalyst, which e.g. may be due to an increased internal combustion engine load, with a consequent increased temperature for the exhaust stream, may therefore mean that stored additives are released and discharged into the vehicle's surroundings via the exhaust pipe. However, such additive / ammonia emissions are not desirable, and in many cases emissions of this type are also regulated by the authorities, i.e. there are also maximum permitted levels for additive emissions.
    In summary, there is a need for an improved method of controlling the supply of additives to a catalyst that overcomes or at least mitigates disadvantages with existing solutions.
    SUMMARY OF THE INVENTION It is an object of the present invention to provide a method which solves the above-mentioned problems. This object is achieved by a method according to the characterizing part of claim 1.
    The present invention relates to a method of supplying additives to a catalytic exhaust gas purification process for purifying an exhaust gas stream from an internal combustion engine of a vehicle, said vehicle comprising means for controlling the supply of said additive to said exhaust gas stream. The method comprises estimating an expected temperature ratio for said exhaust gas purification process by means of a representation of the vehicle base, and controlling said supply of additives based on said estimated temperature ratio.
    This has the advantage that the amount of additive added to the catalytic exhaust gas purification process can be adjusted to the temperature expected. The exhaust gas purification process is usually carried out in a catalyst, such as an SCR catalyst, where additives are stored and then reacted with substances such as e.g. nitrogen oxides in the exhaust stream. Such storage is usually temperature dependent, and by controlling the supply of additives based on the expected temperature, the supply of additives can be controlled to an optimal level.
    This means that at low catalyst temperatures, high storage of additives is possible, whereby the engine can be allowed to run in a more fuel-efficient way (with higher emissions of nitrogen oxides as above) without risking unwanted emissions of additives.
    Normally, if the temperature rises in the catalyst, there is a great risk of unwanted ammonia emissions if the storage in the catalyst is high when the temperature rises. With the aid of the present invention, the storage of additives can be kept substantially as high as the current catalyst temperature allows, while the level can be continuously adapted to expected temperature changes, whereby undesirable additive emissions can be avoided.
    The expected temperature ratio of the catalyst can be determined by determining an expected temperature ratio for said exhaust gas stream.
    Furthermore, the expected temperature ratio of the exhaust stream can be determined by estimating the expected load of the internal combustion engine by means of said representation of the vehicle base, whereby the expected temperature ratio of the exhaust stream can also be determined.
    The representation of the vehicle's surface can e.g. constitute data regarding a slope of the vehicle's surface, the slope of the road in front of the vehicle, and / or data regarding the topography of the road in front of the vehicle. For example. For example, the current position 10 15 of the vehicle together with the said topography data in front of the vehicle in front of the vehicle can be used to determine an expected temperature ratio for a first period of time, such as e.g. the next x seconds, where x can be any number of seconds in the range 5s-600s. The interval can advantageously be 30s or more, as such a long advance allows good opportunities for conversion from a first level to a second lower or third higher level when the catalyst temperature is expected to increase or decrease.
    The amount of additive for supply to the exhaust gas stream as above may also depend on e.g. vehicle mass. If the vehicle, e.g. pga. of it is unladen, has a lower weight, a lower temperature increase can be expected with increased internal combustion engine load compared to if the vehicle is loaded.
    Conversion from a lower level of stored additives to a higher level can take place by increasing the supply of additives.
    Conversion from a higher level of stored additives to a lower level can take place by reducing the supply of additives, and / or by taking one or more additional measures as below.
    When it is determined that a temperature increase is approaching, the amount of added additive can be gradually reduced, e.g. as a function of time, so that the storage of additives is reduced.
    Conversion of the catalyst from a higher support to a lower support may also need to take place quickly, whereby e.g. supply of additives can be switched off completely, whereby flowing exhaust gases will consume stored ammonia. If necessary, the conversion process can be further accelerated by adjusting the injection time, injection angle and / or injection length and / or number of injections for the internal combustion engine so that a larger amount of l0 l5 nitrogen oxides is generated and thus the exhaust gas is supplied, whereby stored ammonia will be consumed at a faster rate. due to the higher concentration of nitrogen oxides in äVgâSGInä.
    Furthermore, the rate of temperature increase, e.g. when the vehicle reaches a blockage, is reduced by temporarily switching off one or more of the commonly occurring engine-mounted units which in operation load the internal combustion engine and thereby raise the temperature of the exhaust gas stream.
    Additional features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments and the accompanying drawings.
    Brief Description of the Drawings Fig. 1a shows a driveline in a vehicle in which the present invention can be used to advantage.
    Fig. 1b shows an example control unit in a vehicle control system.
    Fig. 2 shows an example of a finishing system in a vehicle in which the present invention can be used to advantage.
    Fig. 3 shows the reaction rate of chemical reactions in a vehicle catalyst as a function of the temperature of the catalyst.
    Fig. 4 schematically shows the ability of a catalyst to store additives as a function of temperature.
    Fig. 5 schematically shows a flow chart according to an exemplary process according to the present invention.
    Fig. 6 shows a flow chart according to another exemplary process according to the present invention.
    Detailed Description of Preferred Embodiments Fig. 1a schematically shows a heavy vehicle 100, such as a truck, bus or the like, according to an exemplary embodiment of the present invention. The vehicle 100 schematically shown in Fig. 1a comprises a front pair of wheels 111, 112 and a rear pair of wheels with drive wheels 113, 114 (the invention is also applicable to vehicles where more than one axle is provided with drive wheels, as well as to vehicles with more than one rear axle ). The vehicle further comprises a driveline with an internal combustion engine 101, which in a conventional manner, via a shaft 102 emanating on the internal combustion engine 101, is connected to a gearbox 103, e.g. via a coupling 106.
    A shaft 107 emanating from the gearbox 103 drives the drive wheels 113, 114 via an end gear 108, such as e.g. a conventional differential, and drive shafts 104, 105 connected to said final gear 108.
    The vehicle 100 further includes a post-treatment system for treating exhaust emissions from the internal combustion engine 101.
    The after-treatment system can be of different types as long as the addition of additives takes place in a catalytic exhaust gas purification process. In the exemplary embodiment shown, the aftertreatment system includes a SCR (Selective Catalytic Reduction) catalyst 201. Furthermore, the aftertreatment system may include additional components not shown, such as e.g. additional catalysts and / or particulate filters, which may be arranged upstream and / or downstream of the SCR catalyst 201.
    As mentioned above, an SCR catalyst is a post-treatment system that requires additives to reduce the concentration of nitrogen oxides in the exhaust gases from the internal combustion engine. This additive is often urea-based, and can e.g. consist of AdBlue, which in principle constitutes urea mixed with water. Urea forms ammonia when heated.
    The after-treatment system is shown in more detail in Fig. 2, and comprises in addition to said catalyst 201 a urea tank 202, which is connected to a urea dosing system (UDS) 203.
    The UDS system 203 includes or is controlled by a UDS control unit 204, which generates control signals for controlling the supply of additives so that the desired amount is injected into the exhaust stream 119 from the tank 202 resulting from the combustion in the cylinders of the internal combustion engine 101 by means of an injection nozzle 205 upstream. the catalyst 201.
    In general, UDS systems are well described in the prior art, and exactly how injection of additives takes place is therefore not described in more detail here, but the present invention focuses on a method of calculating the applicable amount of additives for supply to the exhaust stream. the invention can be carried out in an applicable manner.
    Furthermore, control systems in modern vehicles usually consist of a communication bus system consisting of one or more communication buses for interconnecting a number of electronic control units (ECUs), or controllers, and various components located on the vehicle. Such a control system can comprise a large number of control units, and the responsibility for a specific function can be divided into more than one control unit.
    For the sake of simplicity, in Fig. 1a, in addition to the control unit 204, only three further electronic control units 115, 116, 117 are shown.
    The control unit 116 controls, in this embodiment, the motor 101, while the control unit 115 controls the clutch 106 and gearbox 103, respectively (two or more of the motor, gearbox and clutch may alternatively be arranged to be controlled by one and the same control unit, or other, not shown control units) . The control unit 117 is responsible for a so-called forward vision function, which will be described in more detail below.
    Control units of the type shown are normally arranged to receive sensor signals from different parts of the vehicle, e.g. from gearbox, engine, clutch and / or other control units or components on the vehicle, such as e.g. the exhaust gas temperature sensor 206 shown in Fig. 2. The control unit generated control signals are normally dependent on both signals from other control units and signals from components. For example. the control of the control unit 204 of the supply of additives to the exhaust gas stream 119 will e.g. depend on information such as received from one or more additional control units, e.g. the control can be at least partly based on information from the control unit 117 which is responsible for the forward vision function and / or the control unit 115 which is responsible for the function of the gearbox 103, and from the control unit (s) which controls clutch and / or motor functions, such as . the control unit 116.
    The control units are further arranged to emit control signals to various parts and components of the vehicle, such as e.g. means for controlling the injection nozzle 205, for controlling them.
    The present invention can be implemented in any of the above control units, or in any other applicable control unit in the vehicle control system.
    The control is often controlled by programmed instructions. These programmed instructions typically consist of a computer program, which when executed in a computer or controller causes the computer / controller to perform the desired control, such as method steps of the present invention.
    The computer program is usually a computer program product 109 stored on a digital storage medium 121 (see Fig. 1b) such as, for example: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash Memory, EEPROM (Electrically Erasable PROM), a hard disk drive, etc., in or connected to the control unit and executed by the control unit. By changing the instructions of the computer program, the behavior of the vehicle in a specific situation can thus be corrected.
    An exemplary control unit (control unit 204) is shown schematically in Fig. 1b, wherein the control unit 204 may in turn comprise a computing unit 120, which may be constituted by substantially any suitable type of processor or microcomputer, e.g. a Digital Signal Processor (DSP), or an Application Specific Integrated Circuit (ASIC).
    The computing unit 120 is connected to a memory unit 121, which provides the computing unit 120 e.g. the stored program code 109 and / or the stored data calculation unit 120 need to be able to perform calculations.
    The calculation unit 120 is also arranged to store partial or final results of calculations in the memory unit 121.
    Furthermore, the control unit 124 is provided with devices 122, 123, 124, 125 for receiving and transmitting input and output signals, respectively. These input and output signals may contain waveforms, pulses, or other attributes, which of the input signals devices 122, 125 may be detected as information and may be converted into signals which may be processed by the computing unit 120. These signals are then provided to the computing unit 120. The devices 123, 124 for transmitting output signals are arranged to convert signals obtained from the computing unit 120 for creating output signals by e.g. modulate the signals, which can be transmitted to other parts of the vehicle's control system and / or the component (s) for which the signals are intended. Each of the connections to the devices for receiving and transmitting input and output signals, respectively, may be constituted by one or more of a cable; a data bus, such as a CAN bus (Controller Area Network bus), a MOST bus (Media Orientated Systems Transport), or any other bus configuration; or by a wireless connection.
    As mentioned above, the injection nozzle 205 is arranged upstream of the catalyst 201, and the additive is thus supplied to the exhaust gas stream before passing through the catalyst 201.
    As also mentioned, urea is usually supplied in the form of an aqueous solution, which, when supplied to the hot exhaust gas stream, evaporates, decomposes and forms ammonia. It is then this ammonia which constitutes active substance in the chemical reaction in the catalyst 201 which constitutes the purification process itself.
    The ammonia formed follows the exhaust gas flow into the catalyst 201, where the ammonia molecules are adsorbed (adhered) to surfaces in the catalyst 201. The catalyst 201 often comprises a large number of lamellae in order to obtain a large total surface on which the ammonia molecules can adhere. Then, when nitrogen oxides NOX (nitrogen oxides NOX in this specification and the appended claims include both nitric oxide NO and nitrogen dioxide NO2) pass through the catalyst, nitric oxide molecules react with the ammonia molecules adsorbed in the catalyst.
    The catalyst must maintain at least a minimum temperature for the catalytic purification process to occur at all. In the case of an SCR catalyst, urea only evaporates at 200 ° C, which means that the reaction in the catalyst becomes very limited for lower temperatures.
    This is exemplified in Fig. 3, which shows a diagram of how the reaction rate of the reactions of the desired catalytic purification process varies with the temperature T in the catalyst. The origin of the diagram represents T = 200 ° C, and 12 as can be seen in the figure, essentially no reaction takes place at temperatures below 200 ° C, while the reactions for higher temperatures are strongly temperature dependent. From a reaction rate point of view, it is thus desirable but a high catalyst temperature.
    In addition to the fact that the concentration of nitrogen oxides NOX in the exhaust gases varies over time, as depending on the current operating conditions, the ability of the catalyst to store ammonia also varies with temperature.
    This is illustrated in Fig. 4, which shows a diagram of the catalyst's ability, 9, to store ammonia depending on the catalyst temperature T. At lower catalyst temperature, the catalyst's ability to store ammonia is greater compared to at higher temperatures. The catalyst's storage capacity, 9, can e.g. represent the amount of additives, in e.g. grams, which can be adsorbed by the catalyst. As can be seen in the figure, the storage capacity is high for low temperatures (even in this case the origin T = 200 ° C), while it decreases exponentially with increasing catalyst temperature T. This means that if the temperature of the catalyst, for a fully stored catalyst, increases from a temperature T1 to a temperature T2, the catalyst at temperature T2 will be superimposed, which in turn means that the difference in storage capacity, ie. 6nf9T¿ cannot be retained by the catalytic converter, but will be released from the catalytic converter and flow out through the vehicle's exhaust pipe.
    With a rise in temperature in the catalyst, there is thus a great risk of unwanted ammonia emissions if the storage in the catalyst is high. Like nitrogen oxides, NOX is, as mentioned, in many cases also ammonia emissions regulated by the authorities, which is why such emissions are undesirable from both environmental and governmental aspects. l0 l5 l3 A common way to avoid unwanted ammonia emissions is therefore to store lower levels of ammonia than is possible, thereby reducing the risk of unwanted amounts of ammonia being released in the event of sudden temperature rises in the catalyst.
    Ie. at e.g. a temperature T1 does not store the amount of GTM but instead stores a lower amount of 0'Tb The need for ammonia in the catalyst is directly proportional to the amount of nitric oxide in the exhaust gases. With large amounts of nitric oxide, a large amount of ammonia is required in order for the reduction of nitrogen oxides to take place in the most optimal way possible.
    An ammonia molecule is required for each nitric oxide NOX molecule in order to achieve the desired reduction in the catalyst.
    For the catalyst process to be efficient, therefore, the concentration of ammonia, and thus also the amount of dosed urea, must be sufficient to correspond to the concentration of nitrogen oxides NOX in the exhaust gases.
    This means that a reduction in the amount of ammonia added for storage at a certain temperature has the consequence that the reduction of nitrogen oxides NOX in the exhaust gas flow is also reduced. For example. the storage of ammonia can be controlled to a level 0 'such as e.g. entails a degree of reduction of 90%, ie. that 90% of the nitrogen oxides NOX present in the exhaust gas stream are converted to nitrogen gas and water vapor instead of a degree of reduction of e.g. 98% regarding the nitrogen oxides NOX which would be possible if the risk of sudden temperature rises as above was not taken into account.
    According to the present invention, however, a method and a system are provided which enable a higher storage of ammonia to be allowed in the catalyst while at the same time reducing the risk of unwanted ammonia emissions. According to the present invention, this is achieved by, based on a representation of the substrate (the road) along which the vehicle travels, estimating how the temperature of the catalytic exhaust purification will change over time. The temperature of the catalytic exhaust gas purification can e.g. is estimated by estimating how the temperature of the exhaust stream emitted by the combustion engine, whereby also the catalyst temperature is changed by the exhaust stream during its passage through the catalyst, will change for the e.g. 10, 20, 30 or 60 the next few seconds using the representation of the vehicle's surface.
    In this way, injection of additives can be adapted to expected catalyst temperature conditions, whereby also the risk of undesired ammonia emissions can be reduced because the storage can be reduced when a higher temperature is expected.
    At the same time, the invention means that a higher storage of ammonia in the catalyst can be allowed in situations when the temperature is expected to be substantially constant without major temperature increases, which thus increases the efficiency of the use of the SCR catalyst.
    In accordance with a first exemplary embodiment, data on the road in front of the vehicle is used to determine a representation of the vehicle's surface. For example, data from a forward-looking (LA) function can be used to determine a representation of the vehicle's surface.
    The LA function can e.g. include a database of road inclination arranged in the vehicle, either for all roads within an area, such as a region, a country, a continent, etc., or for the road sections along which the vehicle normally travels. By then combining this data with the position of the vehicle, which e.g. can be obtained with the help of a GPS receiver, the vehicle's control system can become aware of what the road looks like in front of the vehicle, and then use this data in different ways, e.g. for cruise control functions.
    With the help of the LA function, it is possible e.g. to determine if the vehicle is approaching inclines, and the internal combustion engine will thus be loaded higher with higher exhaust temperature as a result.
    Road slope data may alternatively, instead of being stored in a database in the vehicle, be arranged to be continuously or at certain intervals sent to the vehicle via some suitable wireless link, where transmitted data e.g. can be controlled by the current position of the vehicle.
    In addition to topographic information, road data may also include information on speed limits, curves, etc. This data may also be used in accordance with the present invention, so that e.g. increased engine load as a result of an acceleration when the permissible speed increases can be taken into account when determining the amount of additive for supply to the exhaust stream.
    The LA function in the present example is implemented via the control unit 117, and data from the LA function can be sent to the control unit 204 (or other applicable control unit) for use in estimating the temperature of the exhaust stream and the amount of additives for supply to the exhaust stream.
    According to an exemplary embodiment of the present invention, road data in front of the vehicle, with or without other vehicle data, is used to estimate how hard the internal combustion engine will operate, e.g. the next 30-60 seconds (or a shorter or longer period of time, such as an arbitrary number of seconds in the range from any number of seconds in the range 1-5s to any number of seconds in the range of 5-1000s), the exhaust gas generated by the internal combustion engine 16 also temperature change in said range can be estimated.
    Thus, by means of the LA function, the control unit 204, e.g. in good time before a future digestion with an associated increase in propulsion demand determine that an increased propellant demand will soon occur, and also relatively accurately calculate what temperature the exhaust gas flow will reach, whereby the heating of the catalyst can also be estimated, and whereby injection of additives can be controlled based on estimated temperature conditions.
    Similarly, even before a hilltop in an uphill slope, at a point where there is a relatively high need for propulsion, based on data from said LA function, it can determine that a reduced need for propulsion will soon occur, but an associated reduction in the exhaust gas temperature, thereby increasing injection. of additives can be started at an optimal time to make the best use of the catalyst purification.
    The information obtained with the aid of look-ahead can be used partly to predict that the vehicle will be driven during relatively static driving without sharp temperature increases, and also to predict when sharp temperature increases are expected.
    Fig. 5 shows a control method according to an exemplary embodiment of the present invention. In step 501, a theoretical value is determined representing the maximum amount of additives that can be injected into the exhaust gas stream and at the same time can also be substantially stored in the catalyst.
    This determination can be performed by means of a model for the catalyst, where the input data of the model consists of: - prevailing temperature T in the catalyst and / or in the exhaust gas stream upstream of the catalyst, e.g. the temperature sensor 206 shown in Fig. 2 is measured, - the flow of the exhaust gas stream (can be measured, for example, by means of an air mass meter 207), and - a reference value Xn fi which represents the desired degree of reduction, e.g. maximum possible degree of reduction, which e.g. can be 98%, but also higher or lower depending on e.g. the design of the catalyst. The catalyst model can e.g. consist of a mathematical description, or of one or more tables with additive amounts for different values of an appropriate number of combinations of input signal values such as a number of different temperatures and a number of different flows. The table may also include such combinations for a number of different reference values.
    This amount value thus constitutes the theoretically most optimal value for the supply of additives, but also constitutes the ratio that risks emission of the largest amount of ammonia with temperature increases. In step 502, therefore, a limit value is determined, such as e.g. 90 or 92% of the urea dosage theoretically possible according to the catalyst model. Exactly as described above in connection with Fig. 4. According to the prior art, the values determined according to step 501 and step 502, respectively, are then compared in a step 503, and the smaller of the two values constitutes the value which is then dosed out by injection. / the dosing nozzle 205. The limitation introduced in step 502 thus means that the dosing will in practice always be reduced to the level specified in step 502.
    According to the present invention, however, a step 504 is used to ease the constraint set in step 502 in applicable situations. In step 504, an expected temperature ratio is estimated by means of a representation of the vehicle's substrate, in this example by means of LA / GPS information, whereby it can be determined whether the vehicle the next 18 following e.g. The 25-30 seconds will be carried out statically (ie on a substantially flat surface) or in a shut-off position, thus no exhaust gas temperature increase is expected, and thus a higher storage of ammonia in the catalyst can be allowed without risk of sudden emissions due. temperature increases.
    Based on the determination made in step 504, a value is generated, which e.g. can vary between 1 and an applicable large or very large value, where a large value is set if no temperature increase is expected, this determined value being multiplied by the value determined in step 502 in step 505, whereby then the result obtained in step 505 is added to the selector 503. By means of the parameter determined in step 504, when no temperature increase is expected, the value obtained in step 502, which is normally lower than the value generated in step 501, can be converted to a value which is guaranteed to exceed that obtained in step 501. the value, whereby optimal dosing of urea according to step 501 can be performed in case no temperature increase is probable.
    The determination in step 504 can be performed continuously, and also generate a parameter that changes as a function of time f (t). Thus, the parameter generated in step 504 can be used not only to choose between the values calculated in step 501 and step 502, respectively, but also to any value therebetween.
    When it is determined that a temperature increase is approaching, the parameter generated in step 504 can be lowered, e.g. successively as a function of time, so that a limitation of the maximum possible storage reappears, whereby the injection of urea, and thus the storage of ammonia, is reduced. A catalyst of the type shown normally has a certain built-in inertia, which means that it can take e.g. 15-30 seconds to reduce ammonia storage to the desired level. If the prevailing temperature is low, and the current storage is thus high, it can also take longer periods such as e.g. one minute to adjust storage to the new higher expected temperature.
    The time at which conversion of the catalyst begins can therefore depend on the current temperature prevailing, as well as on the temperature the catalyst is expected to reach within a certain time. By using an LA function, however, an estimate can be performed for a relatively long time, which is why adaptation to a new temperature level can take place in good time and in the most efficient way.
    The temperature the catalyst is expected to reach can be determined by estimating how much the engine will operate. This determination can be performed using e.g. length / rise for an upcoming ascent. An LA-based solution thus has the advantage that a condition of the vehicle's substrate can be determined for a relatively long distance, whereby a very good control of the urea dosage can be achieved.
    Using the parameter generated in step 504, the storage can be gradually lowered to the desired level by gradually reducing the value of the parameter.
    Conversion of the catalyst from a higher support to a lower support can take place in several ways. For example. the urea dosing can be switched off completely, whereby flowing exhaust gases will consume stored ammonia. If necessary, the conversion process can be accelerated by adjusting the injection angles of the internal combustion engine so that a larger amount of nitrogen oxides is generated and thus the exhaust gas is supplied, whereby stored ammonia will be consumed at a faster rate due to the higher concentration of nitrogen oxides in äVgäSGlfnâ.
    Fig. 6 shows an alternative embodiment of the present invention. In step 601, exhaust gas / catalyst temperature is calculated as a function of time based on LA data. This representation of the temperature is then added to a step 602, which corresponds to step 501 above, the estimated temperature being used together with the catalyst model to constantly calculate the optimal amount of additive for supply based on expected temperature, whereby certain value can be taken into account and adapted to future temperature increases. / reductions.
    It can also be advantageous to take into account the weight and driving resistance of the vehicle crew in the above calculations, as these parameters can affect how much the internal combustion engine must work, and thus the exhaust gas temperature that will be achieved. This data is normally already available in the vehicle's control system, e.g. for using the gearbox control unit 115 when shifting, and this data can thus be supplied to the control unit 204 from the control unit 115.
    Furthermore, so far the invention has been described in connection with a look-ahead LA solution, where the position of the vehicle together with altitude information about the road in front of the vehicle has been described.
    However, the present invention is also applicable to vehicles in the absence of such look-ahead information. An alternative way of determining a representation of the vehicle's surface is to determine a slope. Road slope can e.g. obtained by means of a inclination sensor. This road slope is then used, preferably together with information on the weight and driving resistance of the vehicle crew, to estimate catalyst temperature changes. This data is normally available, 21 at least for an automatic transmission vehicle, already present in the vehicle's control system as this data is used by the gearbox control unit to be able to perform shifts without jerks and unwanted wear in the driveline.
    The driving resistance is a total representation of the resultant of the forces that affect the vehicle during operation and can be calculated with knowledge of the vehicle's speed, the engine's driving torque, the vehicle's configuration and other environmental data.
    The driving resistance can also be used as a representation of the road slope.
    Alternatively, the slope of the vehicle's surface can be determined e.g. with the help of someone from the group: inclinometer, accelerometer, gyro.
    By means of the representation of the substrate in the form of the substrate slope of these data, an engine power output can be estimated, whereby also the temperature in the catalyst can be estimated. In this solution, a slower control can be used, where the limitation introduced in step 502 e.g. can be relieved in situations such as when e.g. the engine load has been even for a certain time, such as e.g. 30 or 60 seconds, whereby the vehicle can be assumed to be in a relatively unchanged section of road, before the parameter in step 504 is set to a value which results in the injection of a larger amount of additive.
    This solution means that a shorter adjustment time for reducing the amount of stored additive is available when the driving resistance increases, whereby during the adjustment it may be required that the urea dosing is switched off completely at the same time as injection angles are adjusted so that high amounts of nitrogen oxides are generated and the exhaust stream is fed for faster use. of ammonia, and thus reduced risk of unwanted ammonia emissions during the temperature rise.
    Vehicles of the above type may further comprise one or more units driven by the internal combustion engine such as e.g. AC compressor, air compressor, fans, etc. In addition, the vehicle can also include external units that are supplied with power by the internal combustion engine via to power take-offs, such as e.g. refrigeration units in refrigerated trucks. When a temperature rise is approaching, such units can, if possible, be switched off in order to reduce the load of the internal combustion engine, and thereby reduce the magnitude of the temperature rise, whereby the risk of undesired emissions when adjusting the storage in the catalyst can be reduced.
    Thus, the present invention enables a higher storage of additives, where also the engine can be allowed to generate a corresponding increase of nitrogen oxides with lower fuel consumption as a result.
    Furthermore, a NOX sensor 208 may be provided at the exhaust stream leaving the catalyst, i.e. downstream of the catalyst, to enable measurements of the exhaust gas content after purification.
    For example. For example, the NOX sensor 208 can be used to enable the vehicle control system to detect faults / malfunctions in the finishing system. The NOX sensor 208 can also be used to verify that added additive has the desired effect.
    One factor that may affect the determination of the amount of additive for supply to the exhaust gas stream as above is the mass of the vehicle. If the vehicle, e.g. pga. of it is unladen, has a relatively low weight, the restriction introduced in step 502 can be eased due to. that the relatively low weight results in lower exhaust temperatures as the internal combustion engine does not need to be loaded as hard as in e.g. a heavily loaded vehicle.
    权利要求:
    Claims (22)
    [1]
    A method of supplying additives to a catalytic exhaust gas purification process for purifying an exhaust gas stream from an internal combustion engine of a vehicle, said vehicle comprising control means for controlling the supply of said additive to said exhaust gas stream, characterized in that said method comprises: - estimating a expected temperature ratio for said exhaust gas purification process by means of a representation of the vehicle's substrate, and - controlling said supply of additives based on said estimated temperature ratio.
    [2]
    The method of claim 1, wherein, said expected temperature ratio for said exhaust gas purification process is an expected temperature ratio for said exhaust stream.
    [3]
    The method of claim 1 or 2, further comprising estimating the expected load of the internal combustion engine by means of said representation of the vehicle substrate, said expected temperature ratio for said exhaust gas purification process being estimated by means of said internal combustion engine load.
    [4]
    A method according to any one of the preceding claims, further comprising, when the amount of additive for supply to said exhaust gas purification level is set to a first level, reducing the amount of additive added to a second, compared to said first level lower level, when an increased temperature for said exhaust gas purification process expected.
    [5]
    A method according to any one of the preceding claims, further comprising, when the amount of additive for supply to said exhaust gas purification level is set to a first level, increasing the amount of added additive to a third compared to said first level higher level when a reduced temperature for said exhaust gas purification process is expected.
    [6]
    A method according to claim 4 or 5, wherein said first level represents a desired degree of reduction of at least one substance in said exhaust gas stream.
    [7]
    The method of claim 6, wherein said substance is nitrogen oxides NOX.
    [8]
    A method according to any one of claims 4-7, wherein a reduction in the amount of added additive is started when an increased temperature for said exhaust gas purification process is expected within a first time.
    [9]
    A method according to any one of claims 4-7, wherein a reduction in the amount of additive added is started when said estimated temperature exceeds a first value.
    [10]
    A method according to any one of the preceding claims, wherein said vehicle further comprises a catalyst, wherein said catalytic purification process is performed by means of said catalyst, and wherein the method comprises determining an expected temperature ratio for said catalyst.
    [11]
    11. ll. A method according to claim 10, wherein said expected temperature ratio for said catalyst is determined by means of a determination of an expected temperature ratio for said exhaust gas stream.
    [12]
    A method according to claim 10 or 11, wherein said amount of additive for supply to said exhaust gas purification process is determined at least in part by means of a model of said catalyst.
    [13]
    A method according to any one of the preceding claims, wherein said representation of the vehicle's substrate constitutes data regarding a slope of the vehicle's substrate, the slope of the road in front of the vehicle, and / or data regarding the topography of the road in front of the vehicle. 10 15 20 25 30 25
    [14]
    Method according to claim 13, wherein a slope of the vehicle's surface is determined by means of control signals to and / or from the engine, and / or by means of the driving resistance of the vehicle.
    [15]
    A method according to any one of the preceding claims, further comprising performing said determination while driving with said vehicle.
    [16]
    The method of claim 10, wherein said catalyst is an SCR catalyst.
    [17]
    A method according to any one of claims 1-16, wherein said additive consists at least in part of urea and / or ammonia.
    [18]
    A method according to claim 4, wherein the conversion of the catalyst from a higher support to a lower support is carried out by means of one or more of the group: - reducing or shutting off the supply of additives, - changing the injection time, injection angle and / or injection length and / or number of injections for said internal combustion engine.
    [19]
    A computer program comprising program code, which when said program code is executed in a computer causes said computer to perform the method according to any one of claims 1-18.
    [20]
    A computer program product comprising a computer readable medium and a computer program according to claim 19, wherein said computer program is included in said computer readable medium.
    [21]
    A system for supplying additives to a catalytic exhaust gas purification process for purifying an exhaust gas stream from an internal combustion engine of a vehicle, said vehicle comprising control means for controlling the supply of said additive to said exhaust gas stream, characterized in that the system comprises: 26 - means for estimating of an expected temperature ratio for said exhaust gas purification process by means of a representation of the vehicle's substrate, and means for controlling said supply of additives based on said estimated temperature ratio.
    [22]
    Vehicle, characterized in that it comprises a system according to claim 21.
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    同族专利:
    公开号 | 公开日
    WO2011133092A1|2011-10-27|
    SE537927C2|2015-11-24|
    EP2561194A1|2013-02-27|
    EP2561194A4|2015-09-02|
    EP2561194B1|2019-07-24|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
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    SE539131C2|2015-08-27|2017-04-11|Scania Cv Ab|Process and exhaust treatment system for treating an exhaust stream|
    SE539134C2|2015-08-27|2017-04-11|Scania Cv Ab|Exhaust gas treatment system and method for treating an exhaust gas stream|
    WO2017034470A1|2015-08-27|2017-03-02|Scania Cv Ab|Method and exhaust treatment system for treatment of an exhaust gas stream|
    SE539133C2|2015-08-27|2017-04-11|Scania Cv Ab|Exhaust gas treatment system and method for treating an exhaust gas stream|
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    SE540738C2|2016-12-08|2018-10-23|Scania Cv Ab|Method and system for controlling a sectional ammonia coverage degree profile for a scr catalyst|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1050395A|SE537927C2|2010-04-21|2010-04-21|Method and system for supplying additives to an exhaust stream|SE1050395A| SE537927C2|2010-04-21|2010-04-21|Method and system for supplying additives to an exhaust stream|
    PCT/SE2011/050470| WO2011133092A1|2010-04-21|2011-04-18|Method and system pertaining to control of additive supply in a vehicle exhaust discharge system|
    EP11772322.1A| EP2561194B1|2010-04-21|2011-04-18|Method and system pertaining to control of additive supply in a vehicle exhaust discharge system|
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