| Device and method for purification of exhaust gas in an internal combustion engine -> Monitor Keywords |
|
|
 
Device and method for purification of exhaust gas in an internal combustion engineRelated Patent Categories: Power Plants, Internal Combustion Engine With Treatment Or Handling Of Exhaust Gas, Methods, Anti-pollutionDevice and method for purification of exhaust gas in an internal combustion engine description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20050241295, Device and method for purification of exhaust gas in an internal combustion engine. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The present invention relates to an apparatus for cleaning exhaust gas from an internal combustion engine and to a method for operating such an apparatus. The apparatus has an exhaust gas line, leading away from the engine, and an ozone source for enriching the exhaust gas stream with ozone. The invention also relates to a method for regenerating a particle filter in an apparatus for cleaning exhaust gas. The invention pertains preferably to Diesel engines that are disposed in particular in motor vehicles. PRIOR ART [0002] From European Patent Disclosure EP 1 026 373 A2, an apparatus for cleaning the exhaust gas stream of an internal combustion engine is known, having an ozone source which serves to enrich the exhaust gas stream with ozone. According to this reference, an oxidizing catalytic converter and downstream of the oxidizing catalytic converter a particle filter are disposed in the exhaust gas line. The delivery of ozone serves to clean the particle filter of particles that have deposited there during engine operation. The enrichment of the exhaust gas stream with ozone is effected between the oxidizing catalytic converter and the particle filter. The ozone then reaches the particle filter along with the exhaust gas. The particles react with the delivered ozone, since ozone has very low reactivity, and self-ignition of the particles takes place even at relatively low temperatures of the exhaust gas stream. The particles oxidize and are thus eliminated, as a result of which the particle filter is cleaned. [0003] From German Patent Disclosure DE 38 34 920 A1, a method and an apparatus for eliminating soot deposited in an exhaust gas filter of an internal combustion engine is also known; discharge currents are generated that on the one hand heat up the soot particles and on the other generate ozone, which oxidizes the soot particles and thus reinforces the burnoff of soot from the filter. [0004] The invention is intended to improve the operation of an exhaust gas cleaning system in terms of energy consumption. According to the invention, this can be accomplished on the one hand by providing that the energy required for regenerating a particle filter is reduced, and on the other by reducing the consumption of the engine itself. Pollutant emissions from an internal combustion engine are also to be improved. ADVANTAGES OF THE INVENTION [0005] The apparatus of the invention for cleaning exhaust gases from an internal combustion engine has an exhaust gas line, leading away from the engine, and an ozone source for enriching the exhaust gas with ozone; the ozone source is embodied such that it generates a continuous ozone-containing gas stream, so that particles flowing in the exhaust gas line are virtually completely oxidized (combusted). This makes it possible to dispense with a particle filter entirely. [0006] Because the particles that occur in engine operation are continuously oxidized with ozone, it becomes possible to dispense with a particle filter in the exhaust gas line, without losses of quality in cleaning the exhaust gas. This reduces the flow resistance in the exhaust gas line and thus the exhaust gas counterpressure and as a result the energy consumption of the engine. The high surface area of the particles, which are very predominantly soot with a primary particle size of less than 100 nm, facilitates oxidation during the dwell time in the exhaust gas train, that is, the time-of-flight of the gases. [0007] The ozone is a strong oxidant for the particles in the exhaust gas stream. Because of the presence of the ozone, the oxidation of the particles begins at low temperatures in the exhaust gas line, which may even be below 150.degree. C. The oxidation of the particles is an exothermic reaction, which takes place when the atmosphere has suitable reaction conditions--that is, the presence of oxygen in sufficient concentration--and a high enough temperature. The ozone is a metastable oxygen compound, which breaks down after a short time, giving up energy. In the process, unbonded, highly reactive oxygen atoms (radicals) are released, which increase the reactivity of the atmosphere, and as a result the ignition temperature for combusting the particles drops considerably. [0008] Because of the metastability of the ozone, it cannot be stored; it must be made as needed and at least in the vicinity of the exhaust gas stream to be cleaned. An ozone source must therefore be provided, in which ozone is generated. Ozone can be recovered from an oxygen-containing atmosphere by supplying energy suitable for splitting oxygen molecules. This can be done for instance by means of electromagnetic alternating fields or uv light. Electrochemical ozone generation is possible, with water as an educt. Enriching the exhaust gas stream with ozone can, in advantageous features of the invention, be done on the one hand by ozone generation in the exhaust gas stream itself, or by ozone generation in an ozone source disposed outside the exhaust gas line. In ozone generation in the exhaust gas stream itself, however, a sufficient quantity of oxygen must be present in the exhaust gas stream itself. This is attainable in the event of lean combustion of the fuel in the engine, or by admixing air into the exhaust gas stream. In the case of external generation of the ozone, this can be done in a reaction chamber through which aspirated ambient air flows. [0009] In a method of the invention for cleaning an exhaust gas stream, which can be employed in particular in an apparatus of the invention for cleaning exhaust gas, a continuous enrichment of the exhaust gas stream with ozone is effected, such that oxidation with complete combustion of the particles in the exhaust gas stream already takes place during the flow through the exhaust gas line, making a particle filter unnecessary. [0010] The metering of the ozone is preferably effected such that the temperature of the exhaust gas stream in the enrichment with ozone generated by the ozone source is above the self-ignition temperature of the (soot) particles. The metering of the ozone can be done such that a particle sensor, which measures the remaining particle content in the exhaust gas stream, is provided in the exhaust gas line, spaced apart downstream from the point of enrichment with ozone. This measurement can also be done indirectly, for instance by way of detecting the exhaust gas temperature in this region of the exhaust gas line. The enrichment with ozone is effected such that the particle content at the particle sensor is below a predetermined limit value. For instance, the predetermined limit value is determined such that it either meets or is below legally specified exhaust gas limit values for particles--that is, soot. In addition or alternatively, it may be provided that the temperature of the exhaust gas stream be detected upstream of the point of enrichment with ozone. The temperature increase between the temperature sensor upstream of the enrichment with ozone and a temperature sensor downstream of the enrichment with ozone is a measure for the energy that is liberated in the combustion of the particles. If this temperature difference is maximized, at the least possible enrichment with ozone (ozone content), then this can be assessed as showing that a maximum degree of combustion of the particles has been reached. [0011] In another aspect of the invention, in an exhaust gas cleaning system that has a particle filter disposed in the exhaust gas line, ozone can be introduced upstream of this particle filter, after the engine is shut off. [0012] Introducing the ozone brings about regeneration of the particle filter. Introducing the ozone, possibly in conjunction with a carrier gas, can be done for instance by means of a blower. The advantage of performing a regeneration of a particle filter with the engine switched off is that the ozone concentration can be kept very high inside the particle filter with little expenditure of energy, since no dilution with the exhaust gas from the engine occurs. Moreover, without an additional exhaust gas stream, the exothermic oxidation of the particles causes a marked increase in the filter temperature, since the convective heat dissipation is reduced substantially because of the lesser flow rate. Both effects lead to a markedly reduced regeneration time and a lesser expenditure of energy. If only such a regeneration of the particle filter is contemplated, or in other words if periodic regeneration is not done during driving, then the ozone generator can be made smaller and hence can be realized less expensively. [0013] The introduction of the ozone is preferably done at a residual temperature of the particle filter that enables a self-ignition of the particles at an attainable ozone concentration. Preferably, the burnoff of the particles in the particle filter can be monitored by means of a temperature sensor. Then it is possible in particular to control the delivery of ozone such that the temperature of the particle filter is above a minimum temperature by a certain amount; the minimum temperature may for instance be approximately 150.degree. C. If there is a decrease in trend to the temperature of the particle filter, then the ozone delivery is increased, to promote the combustion that occurs; if the temperature has risen too far, the ozone delivery is reduced, to prevent damage to the particle filter. In this way, uniform burnoff of the particles can be achieved. [0014] A further aspect of the invention provides that immediately before the start of the engine, the exhaust gas line is rinsed with a gas stream enriched with ozone. [0015] It is known that a certain quantity of hydrocarbon can deposit on the inner surfaces of the exhaust gas line in the exhaust gas train after the engine is switched off. These hydrocarbons can escape when the engine is started, because the oxidizing catalytic converter is still cold and hence is ineffective. These starting emissions can be avoided if the exhaust gas train is rinsed with an ozone-containing gas stream before the starting process, for instance during the preglow phase of a Diesel engine. Because of the presence of the ozone, a combustion of the hydrocarbons that not only eliminates the hydrocarbons but also rapidly increases the temperature in the exhaust gas line occurs. [0016] In particular, it can be provided that the gas stream enriched with ozone be introduced upstream of an oxidizing catalytic converter. This promotes the reaching of the operating temperature of the oxidizing catalytic converter after cold starting. Moreover, with simultaneous rich combustion in the engine, the exhaust gas stream can initially carry along further uncombusted hydrocarbons, which are combusted exothermically because of the presence of the ozone. This provision as well promotes a rapid attainment of the operating temperature of the oxidizing catalytic converter. Adjusting the fuel injection into the combustion chambers of the engine to "late" is equally advantageous for this purpose. With an increasing temperature in the exhaust gas train, the delivery of a gas stream enriched with ozone, or in other words the ozone concentration, can be reduced. DRAWING [0017] Exemplary embodiments of the invention are shown in the drawing and will be described in further detail below; shown are: [0018] FIG. 1: in a schematic illustration, an apparatus of the invention for cleaning exhaust gas, with an ozone source disposed outside the exhaust gas line; [0019] FIG. 2: in a schematic illustration, an apparatus of the invention for cleaning exhaust gas, with an ozone source disposed inside the exhaust gas line; [0020] FIG. 3: in a schematic illustration, an exhaust gas cleaning system with a particle filter; [0021] FIG. 4: the flow chart of a method for controlling the ozone concentration, with continuous enrichment with ozone; Continue reading about Device and method for purification of exhaust gas in an internal combustion engine... Full patent description for Device and method for purification of exhaust gas in an internal combustion engine Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Device and method for purification of exhaust gas in an internal combustion engine patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Device and method for purification of exhaust gas in an internal combustion engine or other areas of interest. ### Previous Patent Application: Injector system for rocket motors Next Patent Application: Exhaust after-treatment system for a lean burn internal combustion engine Industry Class: Power plants ### FreshPatents.com Support Thank you for viewing the Device and method for purification of exhaust gas in an internal combustion engine patent info. IP-related news and info Results in 0.52604 seconds Other interesting Feshpatents.com categories: Canon USA , Celera Genomics , Cephalon, Inc. , Cingular Wireless , Clorox , Colgate-Palmolive , Corning , Cymer , pbckp |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
