EXHAUST SYSTEM COMPONENT HAVING A COMBINATION OF A HEAT EXCHANGER AND A CATALYTIC CONVERTER, MOTOR VEHICLE HAVING THE COMPONENT AND METHOD OF OPERATING THE COMPONENT
A component of an exhaust gas system for an internal combustion engine includes at least one housing with an inlet and an outlet for an exhaust gas and at least one inflow and one outflow for a medium. The component has a heat exchanger around which the exhaust gas can flow. The heat exchanger has a first thermal mass and a catalytic converter body through which the exhaust gas can flow. The catalytic converter body has a second thermal mass. A motor vehicle having a component and a method for operating a component, are also provided.
Latest EMITEC GESELLSCHAFT FUR EMISSIONSTECHNOLOGIE MBH Patents:
- DEVICE FOR PROVIDING A LIQUID REDUCING AGENT HAVING A TANK WITH A TEMPERATURE SENSOR AND MOTOR VEHICLE HAVING THE DEVICE
- Fluid container for a motor vehicle
- EXHAUST SYSTEM, MOTOR VEHICLE HAVING AN EXHAUST SYSTEM AND METHOD FOR OPERATING A MOTOR VEHICLE
- METHOD FOR OPERATING AN EXHAUST GAS TREATMENT DEVICE AND MOTOR VEHICLE HAVING THE DEVICE
- METERING UNIT FOR A REDUCING AGENT, METHOD FOR METERING REDUCING AGENT AND MOTOR VEHICLE HAVING A METERING UNIT
This is a continuation, under 35 U.S.C. §120, of copending International Application No. PCT/EP2009/060563, filed Aug. 14, 2009, which designated the United States; this application also claims the priority, under 35 U.S.C. §119, of German Patent Application DE 10 2008 044 711.0, filed Aug. 28, 2008; the prior applications are herewith incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION Field of the InventionThe present invention relates to a combination of a heat exchanger and a catalytic converter in a common housing as a component of an exhaust system. The component serves, in particular, to recover energy from an exhaust stream and to optimize light-off behavior of the catalytic converter provided in the housing. The invention also relates to a motor vehicle having the component and a method of operating the component.
Exhaust gas from an internal combustion engine of a motor vehicle has thermal energy which can be converted into electrical energy, for example through the use of a thermo-electric generator in order, for example, to charge a battery or some other energy storage device or to supply required energy directly to electric consumers. Energy is therefore available to a greater extent for the operation of the motor vehicle. Such a thermo-electric generator has a plurality of thermo-electric transducer elements. Thermo-electric materials are of a type that can convert the effectively thermal energy into electrical energy (Seebeck effect) and vice versa (Peltier effect). The Seebeck effect is based on the phenomenon of the conversion of thermal energy into electrical energy and is used to generate thermo-electrical energy. The Peltier effect is the converse of the Seebeck effect and is a phenomenon which is associated with the adsorption of heat and is caused in relation to a flow of current through different materials. The Peltier effect has already been proposed, for example, for thermo-electric cooling.
Attempts have already been made to make available corresponding thermo-electric generators for use in motor vehicles. However, such generators have usually been very expensive to manufacture and have been characterized by a relatively low level of efficiency. As a result, it has not been possible to achieve series compatibility. A further decisive feature is the overall size of components for recovering energy from the exhaust gas. In that context, a maximum amount of energy is to be recovered from the stream of exhaust gas accompanied by the smallest possible overall size. At the same time it is to be ensured that the individual components of the emission control system are brought as quickly as possible to the operating temperature at all operating points of the internal combustion engine in order to permit wide-ranging conversion of pollutants which are contained in the exhaust gas.
SUMMARY OF THE INVENTIONIt is accordingly an object of the invention to provide an exhaust system component having a combination of a heat exchanger and a catalytic converter, a motor vehicle having the component and a method of operating the component, which overcome the hereinafore-mentioned disadvantages and at least partially solve the highlighted problems of the heretofore-known devices and methods of this general type. In particular, the intention is to specify a component of an exhaust system which permits the highest possible level of efficiency in terms of the conversion of the thermal energy which is made available from the exhaust gas into thermal energy of a medium of the heat exchanger and which also increases the effectiveness of the emission control of the component at all of the operating points of the internal combustion engine. At the same time, the intention is to obtain a structure which is as compact as possible.
With the foregoing and other objects in view there is provided, in accordance with the invention, a component of an exhaust system for an internal combustion engine. The component comprises at least one housing having an inlet and an outlet for an exhaust gas and at least one inflow and one outflow for a medium, and a heat exchanger around which the exhaust gas can flow. The heat exchanger has at least one first flow path for the medium. The heat exchanger has a first thermal mass and a catalytic converter body through which the exhaust gas can flow. The catalytic converter body has a second thermal mass. The heat exchanger and the catalytic converter body are disposed together in the housing.
The medium which is used in the heat exchanger is, in particular, a fluid, and preferably substantially water can be used, wherein, in particular, also long-chained hydrocarbon compounds, that is to say oils or lubricants, can be used. The component is defined by the fact that the heat exchanger and catalytic converter body represent assemblies of the component which are independent of one another and which accordingly have separate thermal masses or heat contents which are separated from one another. In this context, the heat exchanger is formed, in particular, by tube systems through which a medium flows, so that the tube system forms a first thermal mass, and the catalytic converter body is formed, in particular, by at least partially structured metal foils which are wound, wrapped or stacked and themselves define a second thermal mass. The tube system of the heat exchanger is, in particular, constructed from a plurality of tubes which are connected to one another and which are disposed inside the housing of the component and through which a medium flows along a single flow path or along a plurality of flow paths. The heat exchanger can also be provided as a single-component element, for example as a wall element through which the medium can flow and which has, in particular, breakthroughs, and around which the exhaust gas can therefore flow. In this case, the medium flows through the heat exchanger along a single flow path.
As a result of the configuration of the catalytic converter body and heat exchanger in a housing, it is possible for a very high level of effectiveness of the transfer of heat to be achieved by utilizing the catalytically generated heat, with the result that a maximum amount of thermal energy is carried away through the heat exchanger and, if appropriate, can be converted into electrical energy outside the housing of the component by thermo-electric transducer elements. At the same time, the configuration of the heat exchanger and catalytic converter body in a housing ensures that the exhaust gas and/or the catalytic converter body is/are heated by the heat exchanger, with the result that the catalytic converter body can reach or maintain its operating temperature above the light-off temperature as quickly as possible and for as long as possible. The light-off temperature of the catalytic converter body is defined as the temperature above which the catalytic coating reacts with the pollutants in the exhaust gas.
In accordance with another feature of the invention, the housing has an inner wall, a central axis, a first end side and a second end side disposed along the central axis. The inlet for the exhaust gas is disposed at the first end side and the outlet is disposed at the second end side. The catalytic converter body is disposed along the central axis and has an outer circumferential surface and an inner circumferential surface extending parallel to the central axis. The inner circumferential surface is fluidically connected directly to the inlet, permitting the exhaust gas to flow radially through the catalytic converter body from the inner circumferential surface to the outer circumferential surface. The at least one first flow path of the heat exchanger at least partially surrounds the catalytic converter body at the outer circumferential surface. An annular channel is disposed at the inner wall of the housing. The annular channel is fluidically connected to the outer circumferential surface of the catalytic converter body and directly to the outlet, and the annular channel at least partially surrounds the catalytic converter body and the at least one first flow path.
The catalytic converter body of the present invention, through which there can be radial flow, corresponds, in particular, to the construction of the radial catalytic converters according to International Publication No. WO 02/40838 A1, corresponding to U.S. Pat. No. 7,252,809 or International Publication No. WO 02/81879 A1, corresponding to U.S. Pat. No. 7,276,211, the entire contents of which are hereby incorporated by reference. In this context, it is in particular also possible to use radial catalytic converters with heating elements which, according to one particularly advantageous embodiment, can improve the cold start behavior of the catalytic converter body. In particular, such a heating element, for example in the form of a heating-type catalytic converter, is disposed upstream of the inlet of the housing or inside the inner space which is present in the radial catalytic converter.
In addition to the one exhaust gas inlet and exhaust gas outlet, it is also, of course, possible for a plurality of outlets and inlets to be provided in the housing. The catalytic converter body preferably has a cylindrical construction and has in its interior a cavity through which the exhaust gas can flow from the outlet of the housing. The exhaust gas is, if appropriate, diverted there by diversion devices so that it flows outward through the catalytic converter body in the radial direction and leaves the catalytic converter body through the outer circumferential surface. The at least one first flow path of the heat exchanger is preferably disposed directly on the outer circumferential surface of the catalytic converter body. Given an embodiment of the heat exchanger as a tube system, these tubes run, in particular, in the axial direction parallel to the central axis and are distributed uniformly over the outer circumferential surface of the catalytic converter body. A heat exchanging section over a particularly large surface is generated through such a preferred configuration of the heat exchanger so that the highest possible quantity of the thermal energy which is available in the exhaust gas is transmitted to the medium of the heat exchanger. The heat exchanger is preferably disposed in this case inside the annular channel which preferably surrounds the entire circumference of the catalytic converter body and is disposed between the outer circumferential surface of the catalytic body and the inner wall of the housing. The annular channel is embodied in such a way that it is preferably closed off with respect to the exhaust gas inlet, so that after flowing out of the catalytic converter body the exhaust gas is conducted away through the annular channel accompanied by a preceding and/or simultaneous flow around the heat exchanger in the direction of the exhaust gas outlet. In this context, the housing and the heat exchanger are provided, in particular, with guiding elements for the exhaust gas so that the smallest possible pressure loss due to eddying or other resistances in the exhaust gas stream is achieved. Furthermore, the heat exchanger can also be constructed as a planar hollow element which has, in particular, breakthroughs so that the exhaust gas can flow through and around the hollow element. In this context, a plurality of layers of these wall-shaped elements can also be disposed in combination with pipelines or tube lines between the catalytic converter body and the housing.
In accordance with a further feature of the invention, at least one second flow path is provided which at least partially penetrates the catalytic converter body, and in particular over its entire axial extent. The second flow path of the heat exchanger can have an identical construction to the first flow path in this case. In particular, it is disposed in the catalytic converter body in such a way that it is provided inside a radially outer section of the catalytic converter, so that the exhaust gas, coming from the inlet of the housing, overflows a first catalytically active region of the catalytic converter, and only then flows along the at least one second flow path of the heat exchanger. The catalytic converter body has, for the purpose of accommodating the at least one second flow path, in particular holes or cutouts, into which the structures which are provided for the second flow path can be inserted.
In accordance with an added feature of the invention, the heat exchanger is embodied at least in two stages and the at least one first flow path, which is disposed outside the catalytic converter body, is assigned to a first stage, and the at least one second flow path, which penetrates the catalytic converter body, is assigned to a second stage of the heat exchanger. Implementing the heat exchanger with two stages means, in particular, that the latter has two inflows or outflows through which the at least one first flow path or second flow path can be respectively separately supplied with a medium. In this context, the media can, however, be embodied in different ways or also in the same way. This preferred embodiment ensures that the heat exchanger has, in particular, at least two temperature ranges for the medium, the first temperature range caused by the configuration of the at least one first flow path and the second temperature range caused by the configuration of the at least one second flow path. The media which have different temperatures can then be fed, in the region of a thermo-electric generator, to the transducer elements which are particularly suitable for the respective temperature range. The energy efficiency of a thermo-electric generator or of the component according to the invention is therefore increased further. At the same time, the required volume of the medium which is used to supply thermal energies to the catalytic converter body at critical operating points of the internal combustion engine is kept very small since only the at least one second flow path of the heat exchanger is used to heat the catalytic converter body. It is not necessary in this case for a heated medium to heat and flow through the at least one first flow path. The most rapid possible heating, and therefore operational capability, of the catalytic converter body can be achieved by this advantageous embodiment.
In accordance with an additional feature of the component of the invention, the catalytic converter zones which are disposed in the region of the second flow path can also have relatively low specific thermal capacities so that they heat up more quickly, if appropriate, as a result of the medium, and therefore permit an operational capability of the catalytic converter within a relative short time.
In accordance with yet another feature of the component of the invention, the second flow path of the heat exchanger can also be embodied as a volume which is enclosed in itself without an inflow and outflow for a medium. In such a development, the second flow path is filled with a phase change material which can act as a latent heat storage device for the catalytic converter body. When the phase change material which is provided in the second flow path is heated, the material will change its phase state, for example from solid to liquid, through the absorption of a specific quantity of heat. Lowering the temperature of the catalytic converter body below the light-off temperature due to unfavorable operating points of the internal combustion engine and, in particular, in the case of a cold start can then be compensated through an outputting of heat of the phase change material due to a renewed change of phase, for example from liquid to solid. The catalytic converter body is heated and remains above the light-off temperature. With such an embodiment, a compensation volume which can absorb the change in volume of the medium due to the change of phase is to be provided within the second flow path.
In accordance with yet another feature of the component of the invention, the catalytic converter body has, opposite the at least one second flow path of the heat exchanger, at least one first compensation element which permits the catalytic converter body to expand in the radial direction. This is meant to refer in this case, in particular, to cutouts which can absorb expansion of the catalytic converter in the radial direction without loading the second flow paths of the heat exchanger with compressive stresses or displacing those flow paths. In addition to cutouts, it is also possible to provide structures in the at least partially structured metal foils of the catalytic converter body. The structures can compensate for radial expansion of the catalytic converter body due to the thermal stressing caused by bending or a certain degree of compressibility.
In accordance with yet a further feature of the component of the invention, the catalytic converter body has at least one second compensation element which permits the catalytic converter body to expand in the axial direction. These second compensation elements are, in particular, suitable for compensating for the expansion of the catalytic converter body in the axial direction in such a way that the flow paths which are provided for the exhaust gas are maintained. Furthermore, these second compensation elements are also intended to avoid tensile stresses or compressive stresses which could be transmitted to first or second flow paths. The second compensation elements are integrated, in particular, into holding elements which secure first and/or second flow paths in their position in the housing, in particular in the radial direction. For this purpose, the connections of the second compensation elements to the first flow path and/or to the second flow path can be embodied as sliding seats. According to another advantageous embodiment, the second compensation elements are integrated into the first and/or the second flow path. For this purpose, in particular the flow paths which are constructed in the form of pipelines or tube lines can have bends, or, for example, omega-shaped interlaced connections which permit axial mobility and therefore compensate for expansion of the catalytic converter body in the axial direction. In this case, the holding elements which secure the catalytic converter body and flow paths with respect to one another can also be embodied in a fixed fashion in the axial direction.
In accordance with yet an added feature of the invention, the at least one first flow path and/or the at least one second flow path have/has a catalytically active coating. In addition, regions of the inner wall of the housing or regions of the annular channel can also be provided with a catalytically active coating, with the result that, on one hand, the most complete conversion possible of the pollutants in the exhaust gas is achieved and, on the other hand, the largest possible quantity of thermal energy arising from the exothermic catalytic reaction of the exhaust gas can be conducted away to the heat exchanger. If appropriate, it is also possible to dispense with coating of the flow paths if the transfer of heat is made worse by the catalytic coating.
Coatings for oxidation catalytic converters are preferably provided for the catalytically active coating of the catalytic converter body or of the further regions of the component. An exothermic reaction, which increases the thermal energy in the exhaust gas, is generated in the catalytic converter body as a result of the catalytic conversion of components of the exhaust gas. This further increased thermal energy of the exhaust gas is conducted away by the medium through the heat exchanger and is advantageously converted outside the component into electrical energy. The catalytic converter body and the further regions can, if appropriate, be embodied with various coatings and/or catalysts.
With the objects of the invention in view, there is also provided a motor vehicle, especially a passenger car, comprising a component according to the invention.
With the objects of the invention in view, there is concomitantly provided a method for operating a component. The method comprises providing a component according to the invention, and heating the catalytic converter body, at least at certain times, by using the heat exchanger as a heating element.
Other features which are considered as characteristic for the invention are set forth in the appended claims, noting that the features which are specified individually in the claims can be combined with one another in any desired technically appropriate way and indicate further embodiments of the invention.
Although the invention is illustrated and described herein as embodied in an exhaust system component having a combination of a heat exchanger and a catalytic converter, a motor vehicle having the component and a method of operating the component, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
Referring now in detail to the figures of the drawing for explaining the invention and the technical field in more detail by showing particularly preferred structural variants to which the invention is not restricted, and first, particularly, to
In the left-hand half of the illustration in
The heat exchanger 11 can therefore be operated as a single-stage or as an at least two-stage heat exchanger. Given a parallel connection of the first flow path 15 and the second flow path 23, a single-stage heat exchanger 11 is implemented. Given an embodiment of the heat exchanger 11 with a separate inflow 8 and outflow 9 for the first flow path 15, on one hand, and at least the second flow path 23, on the other hand, a two-stage heat exchanger is implemented which can, in particular, supply differently temperature-conditioned media 10 to a thermo-electric generator so that thermal elements with maximum levels of efficiency for respectively different temperature ranges can be utilized as efficiently as possible. In this context, a first stage 25 of the heat exchanger 11 is formed by the first flow path 15, and a second stage 26 of the heat exchanger 11 is formed by the second flow path 23.
Furthermore, the component 1 has second compensation elements 29 which are, in particular, components of the catalytic converter body 13 and serve to secure the first flow path 15 and/or the second flow path 23. These second compensation elements 29 are suitable, in particular, for compensating for expansion of the catalytic converter body 13 in axial direction 30 due to thermal stressing by virtue of the fact that they are embodied in a particularly compressible fashion.
Claims
1. A component of an exhaust system for an internal combustion engine, the component comprising:
- at least one housing having an inlet and an outlet for an exhaust gas and at least one inflow and one outflow for a medium; and
- a heat exchanger around which the exhaust gas can flow, said heat exchanger having at least one first flow path for the medium, said heat exchanger having a first thermal mass and a catalytic converter body through which the exhaust gas can flow, said catalytic converter body having a second thermal mass;
- said heat exchanger and said catalytic converter body being disposed together in said housing.
2. The component according to claim 1, wherein:
- said housing has an inner wall, a central axis, a first end side and a second end side disposed along said central axis;
- said inlet is disposed at said first end side and said outlet is disposed at said second end side;
- said catalytic converter body is disposed along said central axis and has an outer circumferential surface and an inner circumferential surface extending parallel to said central axis;
- said inner circumferential surface is fluidically connected directly to said inlet, permitting the exhaust gas to flow radially through said catalytic converter body from said inner circumferential surface to said outer circumferential surface;
- said at least one first flow path at least partially surrounds said catalytic converter body at said outer circumferential surface; and
- an annular channel is disposed at said inner wall of said housing, said annular channel is fluidically connected to said outer circumferential surface of said catalytic converter body and directly to said outlet, and said annular channel at least partially surrounds said catalytic converter body and said at least one first flow path.
3. The component according to claim 1, which further comprises at least one second flow path at least partially penetrating said catalytic converter body.
4. The component according to claim 3, wherein:
- said heat exchanger has at least a first stage and a second stage;
- said at least one first flow path is disposed outside said catalytic converter body and is associated with said first stage; and
- said at least one second flow path, at least partially penetrating said catalytic converter body, is associated with said second stage of said heat exchanger.
5. The component according to claim 3, wherein said catalytic converter body has compensation elements, disposed opposite said at least one second flow path of said heat exchanger, for permitting said catalytic converter body to expand in radial direction.
6. The component according to claim 1, wherein said catalytic converter body has compensation elements for permitting said catalytic converter body to expand in axial direction.
7. The component according to claim 3, wherein:
- said catalytic converter body has first compensation elements, disposed opposite said at least one second flow path of said heat exchanger, for permitting said catalytic converter body to expand in radial direction; and
- said catalytic converter body has second compensation elements for permitting said catalytic converter body to expand in axial direction.
8. The component according to claim 3, which further comprises a catalytically active coating disposed on at least one of said at least one first flow path or said at least one second flow path.
9. A motor vehicle, comprising a component according to claim 1.
10. A method for operating a component, the method comprising the following steps:
- providing a component according to claim 1; and
- heating said catalytic converter body, at least at certain times, by using said heat exchanger as a heating element.
Type: Application
Filed: Feb 28, 2011
Publication Date: Aug 11, 2011
Applicant: EMITEC GESELLSCHAFT FUR EMISSIONSTECHNOLOGIE MBH (LOHMAR)
Inventors: SVEN SCHEPERS (TROISDORF), ROLF BRÜCK (BERGISCH GLADBACH), SIGRID LIMBECK (MUCH)
Application Number: 13/036,192
International Classification: F01N 3/28 (20060101); F01N 3/20 (20060101);