Title of Invention

PROCESS FOR PRODUCING A METALLIC HONEYCOMB BODY WITH RECEPTACLE FOR A SENSOR

Abstract

The invention relates to a method of producing a metal honeycomb body (1), comprising at least partially structured (2) pieces of sheet metal (3), with channels (4) that are especially adapted for an exhaust gas of an internal combustion engine to pass through. Said honeycomb body further has at least one receiver (6) for a sensor (7) extending into the interior (5) of the honeycomb body. The inventive method comprises the following steps: producing recesses (8) on at least one piece of sheet metal (3); stacking and/or coiling up the pieces of sheet metal (3) to form a honeycomb structure (9), the at least one piece of sheet metal (3) being disposed in such a manner as to form a receiver (6) that extends into the interior (5); inserting the pieces of sheet metal (3) into a sheathing tube (10) with an opening (11), said opening (11) extending at least partially across the receiver (6); producing, by joining techniques, a link between the pieces of sheet metal (3) and/or with the sheathing tube (10). The inventive method prevents the channels (4) from being damaged during manufacture when receivers (6) for sensors (7) are subsequently produced and allows, for example, an especially effective conversion of exhaust gases.

Full Text

FIELD OF INVENTION The present relates to a process for producing a metallic honeycomb body which comprises at least partially structured metal foils, with passages being formed through which in particularly an exhaust gas from an internal combustion engine can flow. The metallic honeycomb body has at least one receptacle, which extends into the interior of the honeycomb body, for a sensor. BACKGROUND OF INVENTION Honey comb bodies with sensors of this type are used in particular for onboard diagnosis (OBD), the objective of which is the functional monitoring of catalytic converters for example in an exhaust system of an automobile. In this application, catalytic converters are used to convert pollutants (such as for example nitrogen oxides, unsaturated hydrocarbons, carbon monoxide) contained in the exhaust gas into constitutes which can be released into the environment in accordance with the current statutory provisions. On account of the fact that direct measurement of, for example, harmful hydrocarbons by means of a sensor does not currently appear possible, there are currently two methods which are used to monitor the functionality of catalytic converters. The objective of the first method is to determine the level of oxygen stored in the catalytic converter. For this purpose, an oxygen sensor is arranged both upstream and downstream of the catalytic converter, these sensors determining the oxygen content in the exhaust gas. Form this information, it is possible to draw conclusions as to the storage capacity of the catalytic converter and/or as to the progress of aging. The second method uses two thermal sensors, which are arranged directly upstream and downstream of the catalytic converter, to record the change in temperature of the exhaust gas. This is caused by thermal processes inside the catalytic converter, in particular exothermic reactions between the catalytic converter and the exhaust gas. In addition to arrangements of two sensors upstream and downstream of a catalytic converter of this type, German Utility Model DE 881 6154U has described a support body for a catalytic reactor for exhaust gas purification, the honeycomb body of which is composed of a single piece comprising corrugated metal strips. In this case, a sensor is arranged at the support body in such a manner that it extends into the interior of the metal honeycomb body. Furthermore, it is proposed for the opening required for this installation to be produced by means of electron-beam or leaser cutting, cavity sinking or high- speed milling and grinding. Producing an opening of this type after the metallic honeycomb body has been formed has proven to be difficult in terms of the manufacturing technology required. OBJECTS OF INVENTION Working on this basis, it is an object of the present invention to provide a process for producing a metallic honeycomb body which ensures a reliable production process which is suitable for series production. SUMMARY OF THE INVENTION According to the invention, the process for producing a metallic honeycomb body comprising at least partially structured metal foils, with passages being formed, through which in particular an exhaust gas from an internal combustion engine can flow, and which has at least one receptacle, which extends into the interior of the honeycomb body, for a sensor, includes the following steps: - producing recesses at at least one metal foil; - stacking and/or winding the metal foils in order to form a honeycomb structure, the at least one metal foil being arranged in such a manner that at least one receptacle which extends into the interior is formed; - introducing the metal foils into a tubular casing having an opening, the opening extending at least partially over the at at least one receptacle; - producing a connection, by joining technology, between the individual metal foils and/or between the metal foils and the tubular casing. The proposed process is distinguished in particular by the fact that essential production processes for forming the receptacle are performed even before the metal foils are stacked and/or wound to form a honeycomb structure. The result of this is that producing recesses of this type affects only the immediately adjoining areas of the at least one metal foil. By contrast, producing a corresponding receptacle using the conventional processes led to the deformation of a large number of adjacent metal foils, since these were already arranged close together. Deformation of this nature led in particular to passages becoming blocked, which in turn caused, for example, the efficiency of a catalytic converter or the pressure loss to be adversely affected. These drawbacks are avoided by the proposed process according to the invention, in which in particular the machining of each individual foil separately is preferred. According to a further configuration, it is proposed to produce a receptacle in the form of a blind bore. Accordingly, the recesses at the at least one metal foil are to be designed in such a way that after the stacking and/or winding operation they generate a receptacle which extends from the periphery of the honeycomb structure into inner regions. The dimensions of the blind bore are to be selected such that the blind bore is only slightly larger than the sensor which extends into the interior of the honeycomb body. This ensures that, despite a sensor being arranged in the interior of the honeycomb body, a sufficiently large number of passage have a completely continuous wall, providing the surface area required for catalytic conversion of pollutants in the exhaust gas. According to a further configuration, the metallic honeycomb body has metal foils with a thickness which is less than 0.03 mm. When using thin foils, subsequent machining (in the stacked and/or wound state) is particularly difficult, meaning that the proposed process is especially suitable for metal foils of this type. According to yet another configuration of the process, the recesses are produced even before the structure of the metal foils has been generated. It is customary to build up metallic honeycomb bodies using smooth and corrugated metal foils. The corrugated metal foils are introduced into the metal foils using a rolling process. With regard to the production of the recesses, it is advantageous for them to be produced in advance, since it is possible to use relatively simple manufacturing processes. For example, it is possible in particular for the recesses to be stamped or trimmed out of the metal foils. This prevents damage to the structure of the metal foils. Furthermore, it is proposed for the metal foils to be initially at least partially structured and then for at least the metal foils which are intended to produced the receptacle to be stacked, the recesses then being produced with the aid of a high-energy beam or jet. This means in particular laser cutting processes, plasma cutting processes and water/abrasive jet cutting processes. In this case, the number of metal foils which are to be stacked and are machined simultaneously should preferably be restricted to 20, in particular 10 or 5 metal foils. According to yet another configuration of the process, the metal foils are initially stacked and are then wound in and S shape or are arranged in such a way that the metal foils run in an involute form from the inside outwards towards the tubular casing. In this case, the recesses are preferably produced prior to the stacking operation. The S-shaped or involute-shaped arrangement of the metal foils means that they each extend as far as the edge of the honeycomb body or as far as the tubular casing. This has the advantage that it is particularly simple to produce a corresponding recess. To do this, it is sufficiently to provide a predeterminable number of adjacent metal foils, as a function of the dimensions of the sensor, with recesses. The recesses directly form the desired receptacle. By contrast, if the metal foils are arranged helically, it is always necessary, during production of the recesses, to take account of the change in circumference, so that the recess of the wound metal layer is arranged over the recess of the previous metal layer. The recesses are in this case preferably U-shaped, with in particular adjacent metal foils having different depths. The U-shaped configuration of the recesses in particular allows the use of sensors in rod form. The slightly curved arrangement of the metal foils in the vicinity of the tubular casing is taken into account with the aid of preferably slight variations in the depth of the recesses in adjacent metal foils, this also, for example, ensuring the integration of sensors in rod form without the sensors making contact with the metal foils. According to an advantageous configuration of the process, the receptacle is designed in such a way that at least in sections it follows a profile of the metal foils. The result of this is that only a relatively small amount of adjacent metal foils have to be provided with recesses. In this case, the sensor to be used is preferably designed to match the profile of the metal foils. This prevents damage to the metal foils, while having only a very influence on the functionality of the honeycomb structure. Further advantageous configurations and particularly preferred embodiments are explained in more detail on the basis of the accompanying drawings, in which: BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Fig. 1 shows a diagrammatic and perspective view of a metallic honeycomb body having a sensor, Fig. 2 shows a diagrammatic and perspective view of an arrangement of metal foils with recesses, Fig. 3 shows a diagrammatic and perspective view of the sequence of one configuration of the process according to the invention, Fig. 4 diagrammatically depicts a cross section through an embodiment of a metallic honeycomb body with metal foils running in involute form, and Fig. 5 diagrammatically depicts a detailed view of a coated honeycomb structure. DETAILED DESCRIPTION OF PREFERRED EMBODIEMENTS OF INVENTION Fig. 1 shows a metallic honeycomb body 1 which has metal foils which at least in part are designed with structures 2 forming passages 4. A metallic honeycomb body 1 of this type is used in particular to purify exhaust gasses from an internal combustion engine, with the exhaust gas which is to be purified flowing through the passages 4 in the honeycomb body 1. The honeycomb body 1 has a receptacle 6 which extends into the interior 5 of the honeycomb body 1 and in which a sensor 7 is arranged. The receptacle 6 is formed by a number of recesses 8 which have been formed into a suitable number of metal foils 3. The metal foils 3 are in this case wound in an S shape and surrounded by tubular casing 10. Fig. 2 shows a stack of smooth and corrugated metal foils which together form a honeycomb structure 9. The metal foils 3 have a thickness 12 of preferably less than 0.03 mm. A stack of this type is then wound, for example, in an S shape. In order, in the process, by way of example, to produce a receptacle 6 as shown in Fig. 1, some metal sheets have recesses 8 which have a predeterminable depth 14 starting from the edge of the metal foils which subsequently bears against the tubular casing 10. The depth 14 of the recesses 8 in adjacent metal foils 3 is in this case preferably to be designed to differ. In this context, it is advantageous for the metal foils to be machined individually using a cutting process. Fig. 3 diagrammatically depicts the sequence involved in producing the metallic honeycomb body 1, the metal foils 3 of which are wound helically. In this case, a smooth metal foil 3 and a structured metal foil 3 are placed on top of one another and the recesses 8 are produced with the aid of a high-energy beam or jet 13. In the process, by way of example, a nozzle is moved over the metal foils 3 (as indicated by an arrow) in accordance with the desired shape of the recess 8, in order to produce, for example, round recesses 8 with the aid of the water jet/abrasive jet cutting process. The metal foils 3 which have been treated in this way are wound up to form a honeycomb structure, with the distances between the adjacent recesses 8 being designed in such a manner that they always overlap one another during the winding operation. When the honeycomb structure has reached a predetermined diameter, the metal foils 3 supplied are served and the honeycomb structured is introduced into a tubular casing 10. The tabular casing 10 has an opening 11 which is oriented in such a way that it is arranged at least partially above the openings 8. In this way, a receptacle 6 (not shown) is formed, in which a sensor 7 can subsequently be arranged. Fig. 4 diagrammatically depicts a cross section through an embodiment of a metallic honeycomb body 1 with metal foils 3, with the structure 2 (not shown) in this case having been disregarded. The metal foils 3 are in this case arranged in a tubular casing 10, forming an involute-like profile 19. The receptacle 6 formed by the metal metal foils 3 in this case, in a section 18, follows the profile 19, as does a sensor 7 which has been arranged in the receptacle 6 and is shaped suitably. The sensor 7 is in this case fixed in the original 11 in the tubular casing 10 by means of a holder 15. The sensor 7 is of at least partially elastic or deformable design, in order to facilitate the introduction of the sensor 7 into the receptacle 6. The number of the metal foils 3 with recesses 8 (not shown) is in this way limited to less than 20, in particular less than 10. Fig. 5 diagrammatically depicts a detailed view of a coated honeycomb structured 9. The passages 4 of the honeycomb structure 9 are delimited by the metal foils 3, with a metal foil 3 with a structure 2 and a smooth metal foil 3 being wound alternately. The metal foils in this case have a thickness 12 of less than 0.03 mm. In view of the preferred use of honeycomb bodies of this type as catalyst support bodies for exhaust gas purification, the honeycomb structure 9 illustrated has a catalytically active coating 16. During the purification process, the coating 16 comes into contact with the exhaust gas flowing through the passages 4, the precious metal 17 including the coating 16 allowing the pollutants to be converted. The process according to the invention prevents manufacturing damage to passages during the retrospective production of receptacles for sensors and thereby ensures, for example, particularly effective conversion of exhaust gases. LIST OF REFERENCE SYMBOLS WE CLAIM 1. A process for producing a metallic honeycomb body (1), comprising at least partially structured (2) metal foils (3), with channels (4) being formed, adaptable in particular for an exhaust gas from an internal combustion engine to flow, the metallic honeycomb body (1) having at least one receptacle (6) for a sensor (7), extension into an interior (5) of the honeycomb body (1), characterized by comprising the following steps: - producing recesses (8) at at least one metal foil (3), the recesses (8) being produced even before the structure (2) of the sheet metal (3) has been formed; - stacking and/or the metal foils (3) to form a honeycomb structure (9), the at least one metal foil (3) being arranged in such a manner so as to form at least one receptacle (6) which extends into the interior (5); - inserting the metal foils (3) into a tubular casing (10) having an opening (11), the opening (11) extending at least partially across the at least one receptacle (6); - producing a connection, by joining techniques between the individual metal foils (3) and between the metal foils (3) and the tubular casing (10) or between the metal foils (3) and the tubular casing (10). 2. The process as claimed in claim 1, wherein a receptacle (6) is produced in the form of a blind bore. 3. The process as claimed in claim 1 or 2, wherein the metal foils (3) have a thickness (12) of less than 0.03 mm. 4. The process as claimed in one of claims 1 to 3, wherein the recesses (8) are stamped. 5. The process as claimed in one of claims 1 to 4, wherein the metal foils (3) are initially stacked and are then wound in an S shape or are arranged so as to run in an involute form from the inside (5) outwards the tubular casing (10). 6. The process as claimed in claim 5, wherein the recesses (8) are of U- shaped design. 7. The process as claimed in claim 5 or 6, wherein the recesses (8) cf adjacent metal foils (3) have different depths (14). 8. The process as claimed in one of claims 5 to 7, wherein the receptacle (6) is configured in such a way that, at least in sections (18), the receptacle (6) corresponds a profile (19) of the metal foils (3), to enable insertion of a correspondingly shaped sensor (7). This invention relates to a method of producing a metal honeycomb body (1), comprising at least partially structured (2) pieces of sheet metal (3), with channels (4) that are especially adapted for an exhaust gas of an internal combustion engine to pass through. Said honeycomb body further has atleast one receiver (6) for a sensor (7) extending into the interior (5) of the honeycomb body. The inventive method comprises the following steps: producing recesses (8) on at least one piece of sheet metal (3); stacking and/or coiling up the pieces of sheet metal (3) to form a honeycomb structure (9), that at least one piece of sheet metal (3) being disposed in such a manner as to form a receiver (6) that extends into the interior (5); inserting the pieces of sheet metal (3) into a sheathing tube (10) with an opening (11), said opening (11) extending at least partially across the receiver (6); producing by joining techniques, a link between the pieces of sheet metal (3) and/or with the sheathing tube (10). The inventive method prevents the channels (4) from being damaged during manufacture when receivers (6) for sensors (7), are subsequently produced and allows for example, an especially effective conversion of exhaust gases.

Documents:

1118-kolnp-2003-granted-abstract.pdf

1118-kolnp-2003-granted-claims.pdf

1118-kolnp-2003-granted-correspondence.pdf

1118-kolnp-2003-granted-description (complete).pdf

1118-kolnp-2003-granted-drawings.pdf

1118-kolnp-2003-granted-examination report.pdf

1118-kolnp-2003-granted-form 1.pdf

1118-kolnp-2003-granted-form 18.pdf

1118-kolnp-2003-granted-form 2.pdf

1118-kolnp-2003-granted-form 3.pdf

1118-kolnp-2003-granted-form 5.pdf

1118-kolnp-2003-granted-gpa.pdf

1118-kolnp-2003-granted-letter patent.pdf

1118-kolnp-2003-granted-reply to examination report.pdf

1118-kolnp-2003-granted-specification.pdf