| Internal combustion engine exhaust gas conveying device with internal lining, as well as process for production thereof -> Monitor Keywords |
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Internal combustion engine exhaust gas conveying device with internal lining, as well as process for production thereofRelated Patent Categories: Power Plants, Internal Combustion Engine With Treatment Or Handling Of Exhaust GasInternal combustion engine exhaust gas conveying device with internal lining, as well as process for production thereof description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060168938, Internal combustion engine exhaust gas conveying device with internal lining, as well as process for production thereof. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of German Application No. DE 10 2005 004 651.7 filed Feb. 2, 2005. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The invention relates to an exhaust gas conveying apparatus of an internal combustion engine with an internal liner and a process for its fabrication. [0004] The continuous reduction of the permissible pollutant emissions of motor vehicles requires continuous improvement in the treatment of exhaust gas. Special attention is paid to the exhaust gas treatment during the cold start phase. Immediately after the start relatively high quantities of unburned hydrocarbons are emitted. The reason for this, amongst others, is that the catalytic converter has not yet reached its light-off temperature, resulting in an insufficient conversion of the hydrocarbons. [0005] Usually the catalytic converter reaches its light-off temperature about one minute after the start of the engine through the waste heat of the exhaust gas stream so that the catalytic conversion of the exhaust gas begins. [0006] 2. Description of Related Art [0007] In DE 100 48 286 A1 it is proposed to buffer at least a part of the unburned hydrocarbons. For that, a part of the exhaust gas conduit is coated on its inside with an absorbing material, preferably on the basis of zeolite. This coating absorbs part of the unburned hydrocarbons during the cold start phase and releases them again at higher temperatures. Already during the cold start phase the coating of the exhaust manifold is exposed to exhaust gases with temperatures of up to 1050.degree. C. This is a disadvantage since the coating rapidly heats up to it's desorption temperature and consequently it buffers only small amounts of hydrocarbon during the heat up period of the catalytic converter to its light off temperature. Furthermore, the coating which is directly applied to the internal walls of the exhaust manifold is exposed to high mechanical loads. It must withstand large thermal cycles and thermal stresses resulting from the different thermal expansion coefficients of the ceramic and the metal without delamination of parts of the coating which would go into the catalyst downstream. [0008] In another approach stable porous inlays, typically high temperature resistant sintered ceramic bodies, are laid respectively glued into a part of the exhaust conduit. These inlays feature a better form-stability and, with regard to easily condensable exhaust gas constituents, better absorbing and/or adsorbing properties. A disadvantage of this approach is the unadjusted heat transfer or, as the case may be, heat removal. The porous inlays are usually very efficient thermal insulators, so that the exhaust gas is cooled to a much lesser degree by the surfaces of the exhaust gas conduit. Although this is an advantage during the cold start phase, since the catalytic converter reaches its light off temperature faster, this thermal insulation also results in a higher heat load for the catalytic converter during continuous operation, with the danger of overheating the catalyst material. [0009] Since the known sintered ceramics as an inlay for exhaust gas conveying apparatuses or conduits usually feature only a low mechanical strength, the material of the conduit must essentially carry the entire mechanical load, so that the construction of the conduits cannot be designed lighter than in an apparatus without liners. The resulting weight gain of the overall system of the exhaust gas conduits is a disadvantage with respect to the desired lightweight construction. [0010] The objective of the invention is to create an exhaust gas conveying apparatus as well as a process for its fabrication, which features a good buffer capacity for easily condensable exhaust gas constituents as well as a heat balance, which is adjusted to the cold start as well as the continuous operation phase, and with which the weight of the entire exhaust gas conveying apparatus may only be marginally increased. SUMMARY OF THE INVENTION [0011] According to the invention the objective is achieved by an exhaust gas conveying apparatus of an internal combustion engine with internal liner, as well as a process for the fabrication of an exhaust gas conveying apparatus of an internal combustion engine with internal liner. [0012] In a first embodiment according to the invention an exhaust gas conveying apparatus of an internal combustion engine with internal liner is featured, in which the liner features capillary bores, which are open at least towards the exhaust gas conveying side of the liner. The bores can either open single-sided or they can penetrate the liner completely (through holes). [0013] Such a modified structure of the liner of the exhaust gas conveying apparatus with bores as described above enlarges the active surface of the liner. [0014] Here the active surface is referred to as the surface which acts absorptive or adsorptive on the easily condensable exhaust gas constituents such as light hydrocarbons (CHx). The active surface includes the outer as well as the inner surface of the liner which is constituted by the bores. [0015] Such a modified structure facilitates the hydrocarbon condensation, in particular a hydrocarbon capillary condensation, and features in addition a capillary attraction which transports the hydrocarbon-condensate into the interior of the structure and/or into regions of lower exhaust gas concentration and/or retains the hydrocarbon-condensate until its desorption. BRIEF DESCRIPTION OF THE DRAWINGS [0016] Possible embodiments of the invention are shown in the illustrations, which are not to scale. The illustrations are intended to help explain the principle of the invention in more detail and are not meant to impose any restrictions. They show: [0017] FIG. 1 a cut-out of the side of a liner of an exhaust gas manifold opposing the exhaust gas conveying surface with regularly arranged laser drilled through holes. [0018] FIG. 2 capillary bores with different orientation, diameter and length. DETAILED DESCRIPTION OF THE INVENTION [0019] The bores may be introduced into a metallic or ceramic liner. It is advantageous if the internal wall of the apparatus and the liner are made from materials with equal or similar thermal conductivity, e.g. both made from metal, so that even when exposed to large thermal cycles thermal stress is avoided or minimized. The bores may be introduced into a solid or porous liner. Continue reading about Internal combustion engine exhaust gas conveying device with internal lining, as well as process for production thereof... 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