Catalyst body and an exhaust system for a small-size engine and a method for producing the catalyst body

Abstract

The invention relates to a radial-flow annular catalyst body for installation in a muffler housing of a small-size engine, an exhaust system for a small-size engine and a method for producing the catalyst body. The catalyst body consists of a perforated metal foil. In a preferred embodiment, the perforations of the perforated metal foil are adjusted for sound reduction in such a way that the metal foil simultaneously assumes the function of a conventional reflection body. In a further preferred embodiment of the metal foil forming the catalyst body, webs for stiffening the metal foil are arranged between the perforations, which webs are adapted in such a way that they prevent any bulging of the metal foil in the installed state. In a further preferred embodiment, the ends of the metal foil are joined in a detachable interlocking connection. For producing the catalyst body in accordance with the invention, the catalyst body is bent in an annular way from a perforated metal foil strip. Thereafter the ends of the strip are joined by means of an interlocking connection. In a preferred production method, the perforated metal foil strip is cut, punched or broken from previously applied perforation points from endless merchandise. The production from endless merchandise allows a continuous coating process and especially considerable cost savings. The metal foil which can be adapted for sound reduction as a replacement for a conventional muffler unit also has favorable stability properties in addition to the catalytic effect. A conventional reflection body can be omitted because the perforations can be adapted for sound reduction and pollutant reduction. One component of a conventional exhaust system can thus be omitted.

1 . A radial-flow annular catalyst body for installation in a muffler housing of a small-size engine, characterized in that it consists of a perforated metal foil.  
   
   
       2 . A catalyst body according to  claim 1 , wherein the perforations of the perforated metal foil are adapted for sound reduction in such a way that the metal foil simultaneously assumes the function of a conventional reflection body.  
   
   
       3 . A catalyst body according to  claim 1 , wherein the webs are arranged between the perforations for stiffening the metal foil, which webs are adapted in such a way that they prevent any bulging of the metal foil in the installed state.  
   
   
       4 . A catalyst body according to  claim 3 , wherein the webs are aligned according to the forces acting upon the catalyst body.  
   
   
       5 . A catalyst body according to  claim 3 , wherein the webs are aligned coaxially to the longitudinal direction and/or in the circumferential direction of the catalyst body.  
   
   
       6 . A catalyst body according to  claim 1 , wherein the metal foil has a thickness of 0.05 mm to 2 mm.  
   
   
       7 . A catalyst body according to  claim 6 , wherein the metal foil has a thickness of 0.3 mm to 1 mm.  
   
   
       8 . A catalyst body according to  claim 1 , wherein the metal foil is provided with a helical, star-like, trapezoid or wave-like configuration.  
   
   
       9 . A catalyst body according to  claim 1 , wherein the ends of the metal foil are joined with a detachable interlocking connection.  
   
   
       10 . A catalyst body according to  claim 9 , wherein the ends of the metal foil are provided with a hook-like configuration.  
   
   
       11 . A catalyst body according to  claim 9 , wherein the ends of the metal foil are provided with a hook-like configuration.  
   
   
       12 . A catalyst body according to  claim 1 , wherein the perforations are formed by bending away the metal foil.  
   
   
       13 . An exhaust system for small-size engines with a radial-flow annular catalyst body, a muffler unit and a muffler housing, wherein the catalyst body consists of a perforated metal foil.  
   
   
       14 . An exhaust system according to  claim 13 , wherein the perforations of the perforated metal foil are adapted for sound reduction in such a way that the metal foil simultaneously assumes the function of a conventional muffler unit.  
   
   
       15 . An exhaust system according to  claim 13 , wherein the catalyst body is arranged about an inlet of the muffler housing coaxially relative to an inflow direction of the exhaust gas into the muffler housing.  
   
   
       16 . An exhaust system according to  claim 13 , wherein the catalyst body is clamped with pretension against the muffler housing.  
   
   
       17 . A method for producing a radial-flow annular catalyst body for installation in a muffler housing of a small-size engine, wherein the catalyst body is bent in an annular manner from a perforated metal foil strip and the ends of the strip are joined by means of an interlocking connection.  
   
   
       18 . A method according to  claim 17 , wherein the perforated metal foil strips are cut, punched or broken at previously attached perforation points from endless merchandise.  
   
   
       19 . A catalyst body which can be flowed through perpendicularly relative to its upper side and is provided for installation in a muffler housing of a small-size engine, wherein the catalyst body comprises a metal foil provided with cuts.  
   
   
       20 . A catalyst body according to  claim 19 , wherein the metal foil is provided with a helical, star-like, trapezoid or wave-like configuration.  
   
   
       21 . A catalyst body according to  claim 19 , wherein the metallic foil is provided with a single-layer configuration.  
   
   
       22 . A catalyst body according to  claim 19 , wherein the metallic foil is provided with a fanfold configuration.  
   
   
       23 . A catalyst body according to  claim 19 , wherein the metallic foil is stacked in layers.  
   
   
       24 . A catalyst body according to  claim 19 , wherein the metallic foil is provided at its edges with a planar configuration at least in sections.  
   
   
       25 . A catalyst body according to  claim 19 , wherein the metallic foil can be mounted with the muffler housing at its ends by a non-positive connection.  
   
   
       26 . A catalyst body according to  claim 19 , wherein a section formed between two cuts the metal is oriented in one direction with its shape, which direction is opposite to the shape of the metal foil adjacent to the section.  
   
   
       27 . A catalyst body according to  claim 19 , wherein the catalyst body is arranged in the muffler housing with a front housing part and a rear housing part in a zone between two pins joining the housing parts.  
   
   
       28 . A catalyst body according to  claim 19 , wherein the pins are installed in the interior space of the muffler housing.  
   
   
       29 . A catalyst body according to  claim 19 , wherein the catalyst body is installed in the muffler housing in such a way that it fills up a distance which is formed in the interior space of the muffler housing from the front housing part to the rear housing part.  
   
   
       30 . A catalyst body according to  claim 27 , wherein a region which is formed outside of the zone and within the muffler housing is not filled up by the catalyst body.  
   
   
       31 . An exhaust gas system for small-size engines with a muffler housing, wherein the exhaust gas system comprises a catalyst body according to  claim 17 .  
   
   
       32 . A method for producing a catalyst body for installation in a muffler housing of a small-size engine, wherein the catalyst body is folded in a fanfold-like manner from a metal foil provided with cuts and is joined at the ends of the metal foil by means of a non-positive connection with the muffler housing.  
   
   
       33 . A method for producing a catalyst body, characterized by the following steps; 
 application of gas pass-through openings on at least one metal foil which is configured as an endless strip;    coating of the endless strip with catalyst material, and    cutting to size the coated endless strip in a length corresponding to the catalyst body.    
   
   
       34 . A method for producing a catalyst body according to  claim 33 , wherein several metal foils as endless strips which are provided with gas pass-through openings are stacked above one another; 
 that the stacked metal foils are pressed together in a flat manner in predetermined intervals and are joined with each other at the flat pressed sections prior to being catalytically coated.    
   
   
       35 . A method for producing a catalyst body according to  claim 34 , wherein the severing of the endless strip occurs in the flat pressed regions.