Exhaust particulate filter system for an internal combustion engine in the exemplary configuration as a diesel engine

Abstract

Exhaust particulate filter system for an internal combustion engine (2), in particular for a diesel engine (2), comprising two exhaust particulate filters (4, 5) which are permeable to the exhaust gas to be filtered in their respective filter direction (x) and are fluidly connected to each other downstream in such a way that, for the regeneration of one of the exhaust particulate filters (4, 5), it is permeable to the exhaust gas already filtered by the other exhaust particulate filter (4, 5) in the opposite direction to its filter direction (x), wherein the exhaust particulate filters (4, 5) each have an upstream exhaust gas inlet (6, 7) and a downstream exhaust gas outlet (12, 13) opposite the respective exhaust gas inlet (6, 7), of which the respective exhaust gas inlet (6, 7) corresponds simultaneously with the entire filter cross-section of the associated exhaust particulate filter (4, 5) and is fluidly connected to an upstream valve arrangement (8) which is designed toto interrupt the flow of exhaust gas to be filtered to one of the exhaust gas particulate filters (4, 5) and to direct the exhaust gas flowing through this exhaust gas particulate filter (4, 5) during its regeneration against the filter direction (x) back to the combustion engine (2) via a single return line (10), wherein the exhaust gas outlets (12, 13) are fluidly connected to each other via a downstream valve arrangement (14) and can be fluidly connected to an exhaust gas line (15) that conveys the already filtered exhaust gas, and wherein the downstream valve arrangement (14) is configured to at least partially divert filtered exhaust gas flowing out of at least one of the exhaust gas particulate filters (4, 5) in the filter direction (x) through the conveying exhaust gas line (15) and / or to introduce it into one of the exhaust gas particulate filters (4, 5) via its exhaust gas outlet (12, 13) against its filter direction (x) for the purpose of regeneration, characterized in thatthat an exhaust gas catalysis means (11) is arranged between the upstream valve arrangement (8) and at least one of the exhaust gas particulate filters (4, 5), which is fluidly connected to the exhaust gas inlet (6, 7) of the associated exhaust gas particulate filter (4, 5) and to a connection (c, d, l) of the upstream valve arrangement (8), wherein the upstream valve arrangement (8) comprises a four-way valve having two discrete switching positions (E, F) and four connections (a, b, c, d), of which a first connection (a) can be fluidly connected to an exhaust gas line (9) and a second connection (b) to the return line (10) of the internal combustion engine (2), wherein a third connection (c) and a fourth connection (d) are fluidly connected to each of the exhaust gas inlets (6, 7) such that in the first switching position (E) the first connection (a) is connected to the third connection (c) and the second The connection (b) is fluidly connected to the fourth connection (d),while in the second switching position (F) the first port (a) is fluidly connected to the fourth port (d) and the second port (b) to the third port (c), and wherein the downstream valve arrangement (14) comprises a three-way mixing valve with three ports (g, h, i), of which a first port (g) can be fluidly connected to the forwarding exhaust gas line (15), wherein a second port (h) and a third port (i) are fluidly connected to each of the exhaust gas outlets (12, 13) such that the three ports (g, h, i) are at least partially fluidly connected to each other by manipulation of the downstream valve arrangement (14), either in pairs or all together.

Description

The present invention relates to an exhaust gas particulate filter system for an internal combustion engine in the exemplary embodiment as a diesel engine according to the preamble of claim 1. The operation of internal combustion engines in vehicles is subject to increasingly stringent emissions standards. The primary goal is to further reduce emissions of pollutants such as hydrocarbons, carbon monoxide, nitrogen oxides, CO2, and particulate matter. Compliance with the respective limits is the responsibility of the individual vehicle manufacturers. In addition to reduced vehicle weight, optimizations to combustion processes and exhaust gas purification are among the measures available to achieve this. In particular, the particulate matter contained in the exhaust gas of diesel-powered combustion engines requires special aftertreatment systems. Aftertreatment systems employ filters to remove particulate matter, commonly referred to as soot and fine dust, from the exhaust gas stream. Wall-flow filters have become established for this purpose, in which the flowing exhaust gas is forced through a porous filter wall. Particles too large to pass through the individual pores are deposited on the surface of the filter wall. Even smaller particles are separated by agglomeration and adhesion to the filter wall. The deposits that accumulate on the filter wall are commonly known as filter cakes. Such filter walls can be designed in various ways. Preferably, wall-flow filters have a monolithic channel structure formed by the filter walls. The parallel channels within these channels are alternately sealed. In other words, the adjacent channels are alternately sealed at either their first or second end by suitable plugs. This ensures that the exhaust gas initially flows in through the channels that have an open end in the direction of flow. Due to the end closure of these channels, the exhaust gas is then forced through the filter walls that define each individual channel into the surrounding channels. From there, the exhaust gas, filtered in this way, exits through the open ends in the direction of flow. Since the permeability of the filter wall decreases with increasing deposit accumulation, the back pressure of a wall-flow filter continues to rise during its service life. As a result, fuel consumption increases steadily, while the engine's performance decreases until the wall-flow filter becomes completely clogged. Replacing the relevant components as needed would be extremely expensive, especially since, depending on driving conditions, excessive back pressure can occur even after only short distances. Therefore, wall-flow filters require a regeneration process. This means that the solid particles deposited on the filter wall must be removed. Because this must occur during operation, and wall-flow filters, due to their closed design, do not allow for mechanical removal, the deposits are incinerated using a suitable method.Therefore, the removal of the deposited particles occurs through their subsequent conversion into CO2. This requires temperatures of at least 500°C, which are not available from the exhaust gas temperature alone in all operating conditions of the internal combustion engine. To nevertheless ensure the combustion of the deposits is fundamentally possible, the necessary heat is provided, for example, by post-injection of fuel or by the additional arrangement of heating elements. Various embodiments for this purpose are already known in the prior art. For example, US Patent 5,930,994 A and the German translation DE 697 10 263 T2 of EP 0 816 646 B1 describe exhaust emission control devices for removing particles from the exhaust gases of internal combustion engines. Each device comprises two filters arranged parallel to each other, which are fluid-conducting via a common exhaust pipe downstream. Upstream of each of the two filters, a shut-off valve is installed. By opening or closing one of the shut-off valves, the exhaust gas flow through the corresponding filter can be shut off. Upstream of the two filters, they are fluid-conducting via an additional channel bridge. The channel bridge includes an inlet for combustion air, another shut-off valve, and an additional filter. A nozzle for purge air is arranged between each of the two shut-off valves and the corresponding filters.The purge air serves to regenerate the respective filter by being directed through it in the opposite direction. First, the shut-off valve associated with the filter is closed, whereupon the purge air flows through the nozzle in the opposite direction. This carries away any particles trapped in the filter. Simultaneously, the shut-off valve of the manifold is opened, allowing the particle-laden purge air to flow through the manifold and then through the other filter. Since the purge air flows through the auxiliary filter within the manifold, the particles are filtered out. The shut-off valve of the manifold is then closed, and the auxiliary filter is heated by a heating element. Combustion air is then admitted through the manifold inlet and flows to the previously regenerated filter.In this process, the particles deposited in the heated auxiliary filter are burned in combination with the combustion air. Regeneration of the other filter is achieved by appropriately controlling its associated shut-off valve and purge air nozzle. US Patents 7,269,942 B2 and 2004 / 0226290 A1 disclose wall-flow filters for filtering particles from the exhaust gas of an internal combustion engine. Each wall-flow filter comprises a housing with an inlet and an outlet. A filter element is located within the housing between the inlet and outlet. Downstream of the filter element is a throttle valve, which, when actuated, creates a backpressure in the exhaust gas flow. Upstream of the filter element is a slowly rotating, permanently driven rotor. The rotor has an outer ring and spokes connecting it to a central axis of rotation. One segment of the rotor is designed as a closed collection tray. The collection tray opens into a channel nozzle arranged coaxially with the rotor's axis of rotation. Upstream of the rotor, the housing has an external bypass channel with a valve, which is connected to the housing via an opening in the housing.The bypass channel connects the housing opening to the rotor's channel nozzle. This creates a fluid connection between the housing and the rotor's channel nozzle. During the regular filtration phase, the throttle valve is open, allowing exhaust gas to flow freely through the open structure of the rotor and subsequently through the filter body. If filter body regeneration is required, the throttle valve is closed to increase the exhaust gas back pressure within the housing. Simultaneously, the valve within the bypass channel opens. This causes some of the exhaust gas to flow back over the rotor's collection tray. Due to this reversal of direction, the particles trapped in the area of ​​the filter body currently covered by the collection tray are carried along by the already filtered exhaust gas back pressure.The exhaust gas, laden with particles, was routed through the bypass channel into a chamber where the particles could settle. Inside the chamber, the particles could be ignited and burned. After this regeneration of the wall-flow filter, the throttle valve was reopened. Furthermore, US Patents 7,273,514 B2 and 2006 / 0059899 A1 also describe various designs of filter systems for removing particles from the exhaust stream of an internal combustion engine. One variant features a single crossflow filter with a multitude of parallel channels. These channels define the direction of exhaust flow. For filtration, the channels have porous walls that define their circumference. The channels are spaced apart from one another with clearance, allowing exhaust gas flowing laterally through the walls to exit between the channels perpendicular to the flow direction. This crossflow filter is positioned with its ends, opposite each other in the direction of flow, between two synchronously rotating flow templates. The upstream flow template has a ring structure with a radially extending rib.By rotating the flow template, different channels are temporarily covered by the bridge, preventing exhaust gas from flowing into them. In contrast, the opposite flow template has an almost completely closed disc design, comprising only a radially oriented slot. In this way, most of the channels are covered at their ends, while only a few are opened sequentially during the rotation of the flow disc. This allows the exhaust gas entering a multitude of channels to flow through their walls, as most of these channels are closed at their ends by the other flow disc. The exhaust gas, filtered in this way by the cross-flow filter, enters a housing surrounding the filter, from where it can flow out through a housing valve. The exhaust gas can pass through the channels, which are briefly open on both sides due to the position of the flow discs, unfiltered and into a collection chamber. Other designs of the flow templates are also being considered, such as perforated orifices. To regenerate the cross-flow filter, the housing valve is closed, causing the exhaust gas pressure inside the housing to rise. This forces the filtered exhaust gas, which had accumulated in the housing, back through the walls and into the individual channels. During the rotation of the downstream flow disc, only some of the channels are opened at their ends in succession, allowing the excess exhaust gas pressure to be released through these channels into the collection chamber. In this way, the particles that had previously accumulated on the inner surface of the walls are carried along and flushed into the collection chamber. This effect is further enhanced by the incoming exhaust gas flowing through the channels that are occasionally open at both ends. A heating medium located in the collection chamber then combusts the particles flushed out of the cross-flow filter and collected there. Unburned residue can be removed from the collection chamber via a maintenance hatch, if necessary.Furthermore, an embodiment with two parallel wall-flow filters is shown. These are arranged in a common housing, which is divided into three separate chambers with respect to the longitudinal direction of the wall-flow filters. The wall-flow filters are cylindrical, each having a filter body and a tubular extension. The respective extension is longitudinally displaceable within a surrounding tube. Both the extension and the tube have openings in their outer surfaces, which can be aligned with each other. The individual openings are grouped into two opening fields, each located in one of two adjacent chambers of the housing. Exhaust gas can flow into the housing via the central chamber and then passes through one of the opening fields into the wall-flow filter.After filtration, the exhaust gas, now free of particles, then enters a final chamber from which it can escape via a valve. For regeneration, one of the wall-flow filters is axially shifted so that the previously open opening is closed and the other opening is now open. Simultaneously, the valve of the end chamber is closed, creating overpressure and allowing exhaust gas to continue flowing into the end chamber via the second wall-flow filter. This reverses the exhaust gas flow for the wall-flow filter being regenerated, so that the exhaust gas filtered by the other wall-flow filter now flows in the opposite direction. The accumulated particles are carried along in this process. The exhaust gas, now enriched with particles, then passes through the now-open opening into a front chamber and out through a pipe. The particles are then separated from the purified exhaust gas via a circulation separator and can be combusted by a heating medium within it.The regeneration of the other wall flow filter is achieved by reversing the axial displacement of the two wall flow filters. EP 1 807 611 B1 discloses an exhaust gas purification device for an internal combustion engine. This device comprises two separate filters through which exhaust gas to be filtered flows in one direction. Exhaust gas catalysis devices can also be integrated into the filters themselves or installed upstream of them. Each filter is equipped with an additional fuel valve upstream to raise the temperature within the respective filter to at least 500°C. This allows the filters to be regenerated, during which the collected particles within the filters are burned off. Furthermore, by routing the exhaust gas lines in a crisscross pattern, it is possible to return exhaust gas already filtered by one of the filters to the inlet of the other. In this way, the particulate load emitted by the internal combustion engine, particularly during cold starts, can be distributed between the two filters to achieve a uniform load. The known designs enable high mileage for such systems through regeneration. However, the subsequent combustion of the deposited particles in the form of "hot" regeneration requires additional energy. In particular, the mobile combustion process using a heating element ultimately leads to increased fuel consumption. Furthermore, the necessary additional equipment, the sometimes complex design, and the additional calibration effort also result in higher costs for the manufacturer. Regarding the operational reliability of such systems, the high temperatures required for burning the deposits can lead to the undesirable deactivation of the catalyst, which is typically present. Ultimately, this also jeopardizes the structural integrity of the filter, especially since it introduces further robustness risks to the system. German patent DE 10 2010 007 162 A1 describes a system for a vehicle comprising an engine with an inlet and an outlet, as well as a particulate matter retention system. This system has two exhaust gas particulate filters (EGR filters), through which exhaust gas from the engine can flow in its respective filter direction. For regeneration, one of the two EGR filters can be recirculated with exhaust gas already filtered by the other EGR filter, flowing in the opposite direction. The exhaust gas, now loaded with particles, is then returned to the engine inlet to be combusted during the combustion process. For this purpose, the engine outlet is connected via two control valves located upstream of the EGR filters. Each control valve is connected to a return line, with the two return lines joining before an EGR cooler.Downstream of the exhaust particulate filters, they are continuously connected to each other by a fluid-conducting connecting pipe. This connecting pipe is linked via a control valve to a further exhaust line, which leads to a pollutant limitation device. Based on the respective switching positions of the two control valves and the control valve, which only partially opens or closes the exhaust line, the direction of the exhaust gas flow through the two exhaust particulate filters can be determined. German patent DE 37 22 970 A1 discloses a further device for cleaning a particulate filter located in the exhaust pipe of an internal combustion engine. According to one embodiment, this device comprises two particulate filters arranged side by side, through which exhaust gas flows in one direction. Each particulate filter has a throttle valve upstream, which is connected to a return line. The return lines are fluidly connected to the inlet of the internal combustion engine. Downstream, both particulate filters are connected to each other via a Y-shaped manifold, which terminates in a single exhaust pipe. A further throttle valve is arranged between the manifold and the exhaust pipe to regulate the amount of exhaust gas entering the exhaust pipe. By controlling the three throttle valves in total, it is possible to reverse the direction of the exhaust gas flow in one of the two particulate filters.This allows particles accumulated in the respective particulate filter to be dissolved and burned in the combustion chambers of the internal combustion engine via the associated return line. The designs described in DE 10 2010 007 162 A1 and DE 37 22 970 A1 significantly reduce the thermal stress on particulate filters that is otherwise prevalent during regeneration. However, given the known designs, such filter arrangements still offer considerable scope for improvement. Against this background, the present invention aims to improve an exhaust gas particulate filter system in such a way that the thermal stress on the exhaust gas particulate filter due to its regeneration is reduced, the regeneration process to be carried out during operation can be performed more economically overall, and more precise control of the exhaust gas flow paths as well as independent exhaust gas catalysis are also enabled. A further objective is to ensure that particles cannot escape into the environment at any time during operation. According to the invention, this problem is solved by an exhaust gas particulate filter system with the features of claim 1. It should be noted that the features and measures listed individually in the following description can be combined in any technically sensible way and thus demonstrate further embodiments of the invention. The exhaust particulate filter system described below is preferably used in conjunction with a diesel-powered internal combustion engine. According to the invention, the exhaust particulate filter system comprises two or more exhaust particulate filters. The exhaust particulate filters are designed to filter out particles contained in the exhaust gas, such as soot. For this purpose, the exhaust particulate filters are permeable to exhaust gas to be filtered in their respective filter directions. The exhaust particulate filters are connected to each other downstream of their filter direction in such a way that, for the regeneration of one of the exhaust particulate filters, it is permeable to exhaust gas already filtered by the other exhaust particulate filter in the opposite direction to its filter direction. In other words, the exhaust particulate filter to be regenerated is permeated by exhaust gas previously filtered by the other exhaust particulate filter. Each exhaust gas particulate filter has an exhaust gas inlet located upstream of the filter in the direction of flow. The exhaust gas particulate filters and their corresponding exhaust gas inlets are connected in such a way that each inlet corresponds to the entire cross-sectional area of ​​its respective filter. This ensures that exhaust gas flowing in through each inlet is distributed almost uniformly across the entire filter cross-section. This is advantageous because it minimizes the inherent back pressure created by the filter elements within the exhaust gas particulate filters. The exhaust gas particulate filters, which are thus fully exposed to the flow of exhaust gas via their respective exhaust gas inlets, are also fluidly connected to an upstream valve assembly. This valve assembly is preferably separate from the exhaust gas particulate filters and fluidly connected to their exhaust gas inlets only via corresponding exhaust gas lines. This valve assembly is designed to control the exhaust gas flow through the exhaust gas particulate filters. Specifically, the valve assembly is designed to interrupt the flow of exhaust gas to be filtered to one of the exhaust gas particulate filters. Furthermore, the valve assembly is designed to enable the regeneration of one of the exhaust gas particulate filters by allowing the exhaust gas flowing through this filter during regeneration, which now flows against the filter direction, to be directed back to the combustion engine. The exhaust particulate filters have downstream exhaust outlets, which are thus located opposite the exhaust inlets. These exhaust outlets can be interconnected via a downstream valve arrangement and simultaneously connected to an exhaust line that carries the already filtered exhaust gas. In other words, the downstream valve arrangement allows the path taken, either partially or completely, of the now filtered exhaust gas. For this purpose, the downstream valve arrangement is preferably designed to introduce at least part of the filtered exhaust gas flowing out of at least one of the exhaust particulate filters in the direction of flow into the onward exhaust pipe and thus discharge it. Alternatively or in combination with this, the downstream valve arrangement is preferably designed to introduce at least part of the already filtered exhaust gas into one of the exhaust particulate filters via its exhaust outlet against its filter direction (x) in order to regenerate it in the manner described above. According to the invention, the exhaust gas particulate filter system includes an additional exhaust gas catalysis means, which is present in the form of an additional component. This exhaust gas catalysis means is arranged between the upstream valve assembly and at least one of the exhaust gas particulate filters. The exhaust gas catalysis means is fluidly connected to the exhaust gas inlet of the associated exhaust gas particulate filter and to a connection of the upstream valve assembly. In this way, the exhaust gas to be filtered first flows through the exhaust gas catalysis means before entering the respective exhaust gas particulate filter. According to the invention, the upstream valve arrangement is a four-way valve. The four-way valve according to the invention has four ports and two discrete switching positions. Of the four ports, a first port is fluid-conductingly connected to an exhaust line of the internal combustion engine. The exhaust pipe of an internal combustion engine is understood to be one that is suitable for directing exhaust gas to be filtered away from the internal combustion engine to at least one of the exhaust particulate filters. A second connection is fluid-conductingly linked to a return line of the combustion engine. The term "recirculation line" for the combustion engine refers to a line suitable for returning previously filtered exhaust gas, loaded with particles due to its flow through one of the exhaust particulate filters against the filter direction, to the combustion engine. The exhaust gas, thus recirculated and laden with particles, can, for example, be fed directly into the combustion process taking place in the combustion engine. Furthermore, a third and a fourth connection are fluid-conducting and connected to one of the exhaust gas inlets of the exhaust particulate filter. In this way, it is possible for the first switching position to have a fluid connection between the first and third ports, and simultaneously between the second and fourth ports. In other words, in the first switching position, the exhaust gas generated in the combustion engine can be routed through the valve assembly to one of the exhaust particulate filters. At the same time, the exhaust gas flowing back against the filter direction for the regeneration of the other exhaust particulate filter, laden with particles released from the filter being regenerated, can be introduced through the valve assembly into the return line. The second switching position of the upstream valve assembly, in contrast, is designed to essentially reverse the scenario described above. In this position, the first port is connected to the fourth port, and the second port to the third port. In other words, the regeneration of the other exhaust particulate filter can be achieved by introducing the filtered exhaust gas, now flowing against the filter direction, through the valve assembly into the return line, while the already regenerated exhaust particulate filter is supplied with the exhaust gas generated in the combustion engine that still needs to be filtered, also through the valve assembly. The advantageous arrangement of the upstream valve assembly, separate from the exhaust particulate filters, now makes it possible to regenerate either one or the other exhaust particulate filter using two discrete switching positions. In this way, the filtration of the exhaust gas emitted by the combustion engine by at least one of the exhaust particulate filters is permanently ensured at all times during operation. Furthermore, the downstream valve arrangement according to the invention comprises a three-way mixing valve. The three-way mixing valve has three ports. A first port is fluid-conducting to the outgoing exhaust gas line. A second and a third port of the three-way mixing valve are each fluid-conducting to one of the exhaust gas outlets. In this way, all three ports can be fluid-conducting, as required, either in pairs or all together, at least partially, by manipulating the downstream valve arrangement. By using a three-way mixing valve, the flow path for the filtered exhaust gas can be determined simply and cost-effectively. The three-way mixing valve can either have at least two discrete switching positions or function as a mixing valve. In the first case, the exhaust gas would be routed either back from one of the particulate filters into the other or into the exhaust pipe leading to the next (e.g., the tailpipe). In the second case, it would be advantageous to direct certain volumes of the filtered exhaust gas flowing from one of the two particulate filters to the other particulate filter and simultaneously to the exhaust pipe leading to the next.Naturally, the downstream valve arrangement in the form of the three-way mixing valve can also have a switching position that allows the exhaust gas flows exiting both exhaust particulate filters simultaneously to be completely introduced into the onward exhaust pipe. The advantage of this arrangement as a whole lies in the fact that the particles released from the exhaust particulate filter during regeneration are no longer burned within the filter itself or elsewhere by an additional heating element. Instead, according to the invention, the thermal energy already present in the running combustion engine is used to burn the particles. For this purpose, the exhaust gas laden with particles can, for example, be fed directly into the combustion process within the engine via a recirculation line. In this way, additional energy can be obtained beyond that of the fuel to be burned (e.g., diesel). This thermal energy is lost in conventional regeneration processes through combustion within the exhaust particulate filter or a suitable collection vessel, as it is released unused into the environment. The use of the downstream valve arrangement results in an extremely precisely controllable flow path of the exhaust gas with regard to its conveyance. The exhaust particulate filter system according to the invention is independent of any exhaust gas pressures, since the downstream valve arrangement essentially provides a forced flow path for the exhaust gas. In this way, very precise metering of even the smallest quantities and flows of exhaust gas is achievable. The newly possible method of regenerating the exhaust particulate filter system according to the invention significantly reduces the stress on the exhaust particulate filter with regard to the otherwise typical high thermal processes during its regeneration. Since the accumulated particles no longer need to be burned within the exhaust particulate filter, there is a complete departure from the previously prevailing methods for its regeneration. Furthermore, no additional costly devices, such as a cyclone separator, are required to filter the particles from the exhaust stream, which also require extra space and weight. Thanks to the elimination of combustion within the exhaust particulate filter or a suitable collection vessel using additional energy sources, its necessary regeneration can now be carried out more economically overall.Furthermore, the exhaust gas particulate filter system according to the invention enables a simple design with only a few components, thus making overall production more economical. As a possible alternative to the configuration of the upstream valve arrangement as a single four-way valve, which is not covered by the scope of protection of the main claim, it would be conceivable that it could comprise or be formed by two three-way valves. Each of the three-way valves could have three ports and preferably each have two discrete switching positions. Of the three ports of each of the three-way valves, a first port could then be fluid-conductingly connected to the exhaust line of the internal combustion engine. For this purpose, the first ports of the two three-way valves could, for example, be fluid-conductingly connected to each other, with this connection including a connection to the exhaust line of the internal combustion engine, for example in the form of a T-piece. A second port could then be fluid-conductingly connected to the return line of the internal combustion engine.Preferably, two return lines would be provided, so that every second connection of the three-way valves could be fluid-conducted to the combustion engine via its own return line. The third connections of each of the two three-way valves could then preferably be fluid-conducted to one exhaust gas inlet of the exhaust particulate filter. In this way, it would be possible for the first port of each three-way valve to be fluidly connected to the third port in the first switching position. In other words, the exhaust gas flowing into one of the three-way valves from the combustion engine could then pass through it and be routed to the corresponding exhaust particulate filter. In the second switching position of each three-way valve, its second port could then be fluidly connected to the third port. In other words, the recirculation line and the corresponding exhaust particulate filter would be fluidly connected, so that the exhaust gas flowing through the filter for regeneration, now loaded with dissolved particles, would be routed back to the combustion engine through the three-way valve and into the recirculation line. Thanks to the independent control of the separate three-way valves in the upstream valve assembly, it would be possible to supply the exhaust gas particulate filters with exhaust gas to be filtered independently or to regenerate them in the manner described previously. An advantage here would be that both three-way valves could then be adjusted so that the exhaust gas to be filtered could flow through both particulate filters simultaneously. This could result in a significantly reduced back pressure, which would be particularly beneficial under high engine load. As a possible alternative to the configuration of the downstream valve arrangement as a single three-way mixing valve, which is not covered by the scope of protection of the main claim, it would be conceivable that it could comprise or be formed from two proportional valves. Preferably, each of the two proportional valves would then have two connections. A first connection could be fluid-conducting to one of the exhaust gas outlets of the exhaust particulate filters. The respective second connections of the two proportional valves could be fluid-conducting to each other as well as to the downstream exhaust gas line. In this way, the exhaust gas flow through the exhaust particulate filters could be controlled by manipulating just one of the proportional valves. The proportional valves would thus allow stepless adjustment of the exhaust gas flow through them.For example, by slightly opening one of the proportional valves, a small amount of exhaust gas could be directed against the flow direction through one of the particulate filters for regeneration purposes. This would reduce its flow velocity, resulting in a lower particle load. Consequently, a highly advantageous setting could be achieved during regeneration, ensuring that the combustion engine is not suddenly subjected to a high particle load when the particles are returned to the combustion process. This could particularly reduce wear on the combustion engine, as the amount of particles to be burned would not be introduced all at once, but rather in small doses over a suitable period. The invention provides that the exhaust particulate filter system, in addition to its soot filtration capability (i.e., particulate filtration), can also possess catalytic properties. This can be achieved, for example, by providing the filter walls of the filter body in at least one of the exhaust particulate filters with a suitable coating. The exhaust particulate filter system according to the invention, as presented above, offers the highly advantageous possibility of regenerating exhaust particulate filters. Because the thermal combustion of the deposited particles inside the exhaust particulate filters is no longer necessary, their thermal load is significantly reduced. As a result, the exhaust pressure already present during the operation of the combustion engine can be used to remove the particles deposited in the exhaust particulate filters. The flowing exhaust gas carries the particles along and can advantageously transport them to the combustion engine. The thermal energy from the combustion can then be used to burn the particles. Since no additional energy source for thermal combustion within the exhaust particulate filter is required, its necessary regeneration can be carried out much more economically.Ultimately, the design according to the invention allows for the extremely economical and cost-effective production of such an exhaust particulate filter system. In particular, the upstream and downstream valve arrangement allows the use of readily available standard components, so that no additional development and manufacturing are necessary. The invention can be used for a vehicle drive which comprises an internal combustion engine in the exemplary embodiment as a diesel engine and an exhaust particulate filter system with two exhaust filters as described above. The exhaust gas catalysis means described in the invention can, in principle, be any type of catalyst. For example, the exhaust gas catalysis means can be, or include, a diesel oxidation catalyst (DEC), a NOx storage catalyst (LNT lite, LNT, PNA), or a NOx selective catalytic reduction (SCR) catalyst. Furthermore, the filters can be uncoated or coated. The coating can be, for example, any type of precious metal or SCR coating, or another type of coating. Depending on the specific configuration, any type of injection upstream of the optional SCR or filters with an SCR coating is also conceivable. Depending on the design, it is also conceivable that a chamber structurally separate from the combustion chamber of the internal combustion engine may be provided. This chamber can preferably be located within the internal combustion engine or in its vicinity. Its operation involves a fluid-conducting connection between the chamber and the recirculation line, allowing the chamber to be used to combust the particles present in the recirculated exhaust gas using the thermal energy of the internal combustion engine. For this purpose, the chamber can be in conductive contact with the combustion chamber of the internal combustion engine or with other sufficiently hot areas of the engine. In this way, the thermal energy resulting from the regular combustion process of the internal combustion engine (fuel combustion) can be used to burn the particles. Alternatively, the chamber can be used to accumulate the collected particles.This would require the chamber to be emptied regularly. The invention can also be used for a suitably equipped vehicle. For this purpose, the vehicle can include an internal combustion engine which has an exhaust particulate filter system with two exhaust particulate filters as described above. Further advantageous details and effects of the invention are explained in more detail below with reference to the exemplary embodiments schematically illustrated in the figures. The figures show: Fig. 1 the construction of a vehicle drive with an exhaust particulate filter system according to the invention in a first switching position E, Fig. 2 the vehicle drive from Fig. 1 in a modified second switching position of its exhaust particulate filter system F, Fig. 3 a variant of the vehicle drive with an alternatively configured exhaust particulate filter system in a first switching position N / M, Fig. 4 the vehicle drive from Fig. 3 in a modified second switching position M / N of its alternatively configured exhaust particulate filter system, Fig. 5 the vehicle drive from Figs. 3 and 4 in a modified third switching position M / M of its alternatively configured exhaust particulate filter system, and Fig. 6 the vehicle drive from Figs. 1, 2, 3, 4 to 5.5 in another possible alternative design of its exhaust particulate filter system. The illustrations for Figs. 3, 4, 5 to 6 show embodiments which are not covered by the scope of protection of the skin claim. Fig. 1 shows the schematic structure of a vehicle drive 1 according to the invention. The vehicle drive 1 comprises an internal combustion engine in the present form of a diesel engine 2 and an exhaust gas particulate filter system 3. The exhaust gas particulate filter system 3 has two exhaust gas particulate filters 4, 5 arranged parallel to each other, which are permeable in their respective filter direction x with exhaust gas to be filtered from the operating internal combustion engine 2. The two exhaust particulate filters 4, 5 each have an upstream exhaust gas inlet 6, 7, which corresponds simultaneously to the entire filter cross-section of the respective exhaust particulate filter 4, 5 in a manner not shown in detail. The exhaust gas inlets 6, 7 are fluid-conductingly connected to an upstream valve assembly 8. As can be seen, the upstream valve assembly 8 is designed as a four-way valve with a total of four ports a, b, c, d. In this configuration, it has two discrete switching positions E, F, of which the four-way valve is shown here in a first switching position E. A first port a of the four-way valve is fluidly connected to an exhaust line 9 of the combustion engine 2, while a second port b is fluidly connected to a return line 10 of the combustion engine 2. Furthermore, a third port c is fluidly connected to the exhaust inlet 6 of the exhaust particulate filter 4 located at the top in Fig. 1, via an exhaust catalytic converter 11. This also applies to a fourth and final port d of the valve assembly 8, which is likewise fluidly connected to the exhaust inlet 7 of the exhaust particulate filter 5 located at the bottom in Fig. 1, via an exhaust catalytic converter 11. The exhaust line 9 is interrupted insofar as it also contains an exhaust catalytic converter 11. Downstream of the two exhaust particulate filters 4, 5, they are visibly connected to each other by a fluid-conducting connection. For this purpose, the exhaust particulate filters 4, 5 have exhaust outlets 12, 13 opposite their exhaust inlets 6, 7. These outlets are connected to each other and simultaneously to a conveying exhaust line 15, which serves to convey the exhaust gas flowing through the two exhaust particulate filters 4, 5, by means of a downstream valve arrangement 14. The downstream valve arrangement 14 is thus designed to at least partially divert the filtered exhaust gas flowing out of at least one of the exhaust particulate filters 4, 5 in the direction of flow x through the conveying exhaust line 15 and / or to introduce it into one of the two exhaust particulate filters 4, 5 via its respective exhaust outlet 12, 13 in the opposite direction of its filtering direction x for the purpose of regeneration.Finally, the forwarding exhaust gas line 15 is also fluidly connected to a downstream exhaust gas catalysis device 11. The exhaust gas catalysis means 11 shown in Figures 1 and 2, as well as in the embodiments not covered by the scope of protection of the main claim according to Figures 3, 4, 5 to 6, are to be understood as optional. The invention provides that these means can indeed be arranged at the locations shown. However, these locations preferably only mark the places where only one or – with respect to the upstream position upstream of the exhaust particulate filters 4, 5 – two exhaust gas catalysis means 11 can be arranged simultaneously. Therefore, the invention is not limited to the arrangement of the exhaust gas catalysis means 11 at all locations simultaneously as shown. The downstream valve assembly 14 is a three-way mixing valve with a total of three ports g, h, i. Of these ports g, h, i, the first port g is fluid-conducting to the exhaust gas line 15, while the second port h and the third port i are fluid-conducting to each of the two exhaust gas outlets 12, 13. Therefore, the three ports g, h, i, and consequently the exhaust gas outlets 12, 13 of the exhaust particulate filters 4, 5 and the exhaust gas line 15, can be fluid-conductingly connected to each other, either in pairs or all together, by manipulating the downstream valve assembly 14, either in pairs or at least partially.In this way, the exhaust gas flowing through and thus filtered by one of the two exhaust particulate filters 4, 5 can be redirected by the downstream valve arrangement 14 in such a way that it can flow into the other exhaust particulate filter 4, 5 against the filter direction x for regeneration and be directed back through it to the combustion engine 2. Looking back at the upstream valve arrangement 8, it is designed to interrupt the flow of exhaust gas to be filtered to one of the two exhaust particulate filters 4, 5 in the filter direction x. In the current switching position E, this applies to the lower exhaust particulate filter 5. Thus, initially only the upper exhaust particulate filter 4 is permeated with exhaust gas in the filter direction x, while the filtered exhaust gas exiting it is routed back into the lower exhaust particulate filter 5 via the downstream valve arrangement 14. This ensures that the lower exhaust particulate filter 5 is permeated with already filtered exhaust gas during its regeneration, against the filter direction x, which is then routed back to the combustion engine 2 via the first position E of the upstream valve arrangement 8. Fig. 2 shows the second switching position F of the upstream valve arrangement 8 from Fig. 1. In this second switching position F, the first port a is connected to the fourth port d and the second port b to the third port c. It is clear, without further explanation, that this second switching position F serves to regenerate the other exhaust gas particulate filter 4 (shown above) by allowing already filtered exhaust gas to flow through it against the direction of flow x. Fig. 3 shows an alternative embodiment to the upstream valve arrangement 8, which is not covered by the scope of protection of the main claim. As can be seen, this embodiment is formed from two three-way valves, each comprising three connections j, k, l. Each of the two three-way valves has two discrete switching positions M, N. In contrast to the representation in Fig. 1, there are now a total of two return lines 10. A first connection j in each case is connected to the exhaust line 9 of the internal combustion engine 2, while a second connection k in each case is fluid-conducting to one of the two return lines 10 of the internal combustion engine 2. A third connection l of each of the two three-way valves is fluid-conducting to one of the two exhaust inlets 6, 7, which in this case is achieved via the interposition of the means for exhaust gas catalysis 11. In the first switching position M shown here for the upper three-way valve of the upstream valve assembly 8, the first port j is fluid-conductingly connected to the third port l. In the second switching position N shown with respect to the lower three-way valve of the upstream valve assembly 8, the second port k is fluid-conductingly connected to the third port l. In this way, the exhaust gas of the internal combustion engine 2, in this exemplary embodiment a diesel engine 2, is introduced into the upper exhaust particulate filter 4 via the upper three-way valve. Upon exiting the upper exhaust particulate filter 4, this exhaust gas is at least partially redirected by the downstream valve assembly 14 such that it now flows against the filter direction x through the lower exhaust particulate filter and back to the internal combustion engine 2 via the lower return line 10 through the lower three-way valve. Fig. 4, the embodiment of which is not covered by the scope of protection of the main claim, serves to illustrate the situation already shown in Fig. 2, in which the upper exhaust particulate filter 4 is now being regenerated. To avoid repetition, it should be mentioned here that the switching positions M, N of the two upper three-way valves of the upstream valve arrangement 8 have changed, so that the lower three-way valve is in the first switching position M and the upper three-way valve is in the second switching position N. Fig. 5, the illustration of which is also not covered by the scope of protection of the main claim, shows the case in which both three-way valves of the upstream valve arrangement 8 are in the first switching position M. It is clear here that no regeneration of either of the two exhaust particulate filters 4, 5 takes place, but rather that both exhaust particulate filters 4, 5 serve to filter the exhaust gas simultaneously. Thus, the exhaust gas flows through both exhaust particulate filters 4, 5 at the same time and can flow downstream into the exhaust pipe 15. Fig. 6, the embodiment of which is also not covered by the scope of protection of the main claim, is limited to the illustration of the downstream part of the exhaust particulate filter system 3. As can be seen, the downstream valve arrangement 14 is formed here from two proportional valves 16, 17. The two proportional valves 16, 17 each have two ports o, p, of which a first port o is fluid-conducting to one of the two exhaust outlets 12, 13. In contrast, the respective second ports p are fluid-conducting to each other and simultaneously to the downstream exhaust line 15. Depending on the setting of the two proportional valves 16, 17, the exhaust flow through the two exhaust particulate filters 4, 5 can therefore be regulated by manipulating at least one of the two proportional valves 16, 17. Reference symbol list: 1 Vehicle drive 2 Combustion / diesel engine of 1 3 Exhaust particulate filter system of 1 4 Exhaust particulate filter of 3 5 Exhaust particulate filter of 3 6 Exhaust inlet of 4 7 Exhaust inlet of 5 8 Upstream valve assembly 9 Exhaust pipe of 2 10 Recirculation pipe of 2 11 Exhaust catalytic converter of 1 12 Exhaust outlet of 4 13 Exhaust outlet of 5 14 Downstream valve assembly 15 Exhaust pipe, conveying 16 Proportional valve of 14 17 Proportional valve of 14 a First port of 8 b Second port of 8 c Third port of 8 d Fourth port of 8 E First switching position of 8 (four-way valve) F Second switching position of 8 (four-way valve) g First port of 14 h Second port of 14 i Third port of 14 j First port of 8 k Second port of 8 l Third port of 8 M first switching position of 8 (three-way valve) N second switching position of 8 (three-way valve) o first connection of 16, 17 p second connection of 16, 17 x filter direction of 4,5,

Claims

Exhaust particulate filter system for an internal combustion engine (2), in particular for a diesel engine (2), comprising two exhaust particulate filters (4, 5) which are permeable to the flow of exhaust gas to be filtered in their respective filter direction (x) and are fluidly connected to each other downstream in such a way that, for the regeneration of one of the exhaust particulate filters (4, 5), it is permeable to the flow of exhaust gas already filtered by the other exhaust particulate filter (4, 5) in the opposite direction to its filter direction (x), wherein the exhaust particulate filters (4, 5) each have an upstream exhaust gas inlet (6, 7) and a downstream exhaust gas outlet (12, 13) opposite the respective exhaust gas inlet (6, 7), of which the respective exhaust gas inlet (6, 7) corresponds simultaneously with the entire filter cross-section of the associated exhaust particulate filter (4, 5) and is fluidly connected to an upstream valve arrangement (8) which is designed toto interrupt the flow of exhaust gas to be filtered to one of the exhaust gas particulate filters (4, 5) and to direct the exhaust gas flowing through this exhaust gas particulate filter (4, 5) during its regeneration against the filter direction (x) back to the combustion engine (2) via a single return line (10), wherein the exhaust gas outlets (12, 13) are fluidly connected to each other via a downstream valve arrangement (14) and can be fluidly connected to an exhaust gas line (15) that conveys the already filtered exhaust gas, and wherein the downstream valve arrangement (14) is configured to at least partially divert filtered exhaust gas flowing out of at least one of the exhaust gas particulate filters (4, 5) in the filter direction (x) through the conveying exhaust gas line (15) and / or to introduce it into one of the exhaust gas particulate filters (4, 5) via its exhaust gas outlet (12, 13) against its filter direction (x) for the purpose of regeneration, characterized in thatthat an exhaust gas catalysis means (11) is arranged between the upstream valve arrangement (8) and at least one of the exhaust gas particulate filters (4, 5), which is fluidly connected to the exhaust gas inlet (6, 7) of the associated exhaust gas particulate filter (4, 5) and to a connection (c, d, l) of the upstream valve arrangement (8), wherein the upstream valve arrangement (8) comprises a four-way valve having two discrete switching positions (E, F) and four connections (a, b, c, d), of which a first connection (a) can be fluidly connected to an exhaust gas line (9) and a second connection (b) to the return line (10) of the internal combustion engine (2), wherein a third connection (c) and a fourth connection (d) are fluidly connected to each of the exhaust gas inlets (6, 7) such that in the first switching position (E) the first connection (a) is connected to the third connection (c) and the second The connection (b) is fluidly connected to the fourth connection (d),while in the second switching position (F) the first port (a) is fluidly connected to the fourth port (d) and the second port (b) to the third port (c), and wherein the downstream valve arrangement (14) comprises a three-way mixing valve with three ports (g, h, i), of which a first port (g) can be fluidly connected to the forwarding exhaust gas line (15), wherein a second port (h) and a third port (i) are fluidly connected to each of the exhaust gas outlets (12, 13) such that the three ports (g, h, i) are at least partially fluidly connected to each other by manipulation of the downstream valve arrangement (14), either in pairs or all together.

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