Abstract:
A reactor is made deformable by thermal stresses, as the construction thereof includes accordion type portions. The reactor comprises an inner core shell containing inlet and outlet pipe sections formed integral therewith, and extending outwardly through an outer core shell to an outer shell member. Each shell member consists of first and second shell counterparts which may be fixed together in a common plane.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a deformable reactor wherein the unburned constituents contained in the exhaust gases discharged from the combustion chamber of an internal combustion engine are oxidized. 
     In connection with purification of the exhaust gases of internal combustion engines, it is well known in the art that, of the noxious constituents contained in the exhaust gases of the engine, carbon monoxide and hydrocarbons are oxidized in a reactor disposed downstream of the combustion chamber of the engine into harmless water and carbon dioxide. This oxidation reaction carried out in the reactor raises the reactor temperature to an excessively high level, but the reactor temperature is lowered and cooled when engine operation is stopped. The thermal stress depends on the excessively high temperature, and the considerable temperature change damages the reactor. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide an improved reactor which does not occur thermal damage caused by the thermal stress applied thereto during reactor temperature change. 
     Another object of the present invention is to provide an improved reactor of the construction capable of preventing local concentration of the thermal stresses applied to the reactor. 
     A further object of the present invention is to provide an improved reactor in which its exhaust gas inlet and its exhaust gas outlet are formed integrally with its inner core defining therein a reactor chamber for oxidation of the unburned constituents contained in the exhaust gases from the engine. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features and advantages of the reactor according to the present invention will be more apparent from the following description with reference to accompanying drawing in which like reference numerals indicate like parts and elements, and in which: 
     FIG. 1 is a vertical cross-section view of a prior art reactor; 
     FIG. 2 is a cross-sectional view taken along the line I--I of FIG. 1; 
     FIG. 3 is a vertical cross-section view of preferred embodiment of a reactor in accordance with the present invention; 
     FIG. 4 is a cross-sectional view taken along the line II--II of FIG. 3; and 
     FIG. 5 is a vertical cross-section view of another preferred embodiment of the reactor in accordance with the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIGS. 1 and 2, there is shown a prior art reactor 10 of the construction in which inlet pipes 12 project into and open to the reaction chamber 14 defined in an inner core shell 16. The inner core shell 16 is disposed within an outer core shell 18 which is, in turn, disposed within an outer shell 20. Insulating material is disposed between the inner surface of the outer shell 20 and the outer surface of the outer core shell 18. Reference numeral 24 indicates an outlet pipe. In this prior art reactor 10, the inlets 12 slidably contact particularly with the outer core shell 18 through devices 26 for allowing slidable contact between the outer surface of the inlet pipes 12 and the outer core shell 18. Accordingly, the inlet pipes 12 are allowed to expand and contract in their axial and radial directions. 
     In making this type of a reactor, the outer shell 20, the outer core shell 18, the inner core shell 16, the inlet pipes 12, the outlet pipe 24, the slidable devices 26 etc. are, at first, separately made, and thereafter these parts are assembled by welding and inserting one part into the other part. Accordingly, this type of a reactor is constructed from a considerably large number of parts causing a complex construction thereof, and therefore requires a relatively long time for assembly thereof inviting difficulty in production. 
     In view of the above, the present invention contemplates to overcome the disadvantages of the prior art reactor by forming the inlet pipes integrally with the reactor proper in which the thermal expansion and contraction of the inlet pipes are absorbed by the total deformation of the reactor, deleting the slidable device 26. 
     FIGS. 3 and 4 illustrate a preferred embodiment of a reactor 30 in accordance with the present invention, for oxidation of the unburned constituents contained in the exhaust gases discharged from the combustion chamber of an automotive internal combustion engine (not shown). The reactor 30 is composed of an outer shell 32 within which an inner core shell 34 defining therein a reaction chamber 35 is disposed spaced apart from the inner surface of the outer shell 32 to form a space (no numeral) between the inner surface of the outer shell 32 and the outer surface of the inner core shell 34. As shown, the inner core shell 34 is secured at its inlet portion 36 and at its outlet portion 38 to the inner surface of the outer shell 32. An outer core shell 40 is disposed in the space between the outer shell 32 and the inner core shell 34 to divide the space into a first insulation chamber 42 formed between the inner surface of the outer core shell 40 and the outer surface of the inner core 34 and a second insulation chamber 44 formed between the outer surface of the outer core shell 40 and the inner surface of the outer shell 32. The second insulation chamber 44 is filled with insulating material (no numeral). As seen, the outer core shell 40 is secured to the outer surface of the inlet and outlet portions 36 and 38 of the inner core shell 34. Reference numerals 46a indicate flange portions for securing the reactor 30, for example, to the cylinder head (not shown) of an internal combustion engine and 46b a flange portion for connecting the outlet portion 38, for example, to an exhaust pipe of the engine (not shown). 
     When making this reactor 30, first and second outer shell counterparts 32a and 32b, first and second inner core shell counterparts 34a and 34b, and first and second outer core counterparts 40a and 40b are, at first, individually or separately formed, for example, by press work. The respective counterpart is shaped as splitted by a common surface A including the center axes (not identified) of the inlet portions and the center axis (not identified) of the outlet portion 38 as shown in FIG. 3. In this step, a first inlet portion counterpart 36a and a first outlet portion counterpart 38a are integrally formed with the first inner core shell counterpart 34a, whereas a second inlet portion counterpart 36b and a second outlet portion counterpart 38b are integrally formed with the second inner core shell counterpart 34b. It will be understood that each counterpart is formed from a metal sheet. Thereafter, the first and second inner core counterparts 34a and 34b are combined or joined at the surface A by welding or seaming (joining of the edges of sheet-metal parts by interlocking folds) to form the inner core shell 34, in which the first and second inlet portion counterparts 36a and 36b are combined to form the inlet portions 36 and first and second outlet portion counterparts 38a and 38b are combined or joined to form the outlet portion 38. Then, the first and second outer core shell counterparts 40a and 40b are secured to the outer surfaces of the combined inlet portions 36 and the combined outlet portion 38, combining the counterparts 40a and 40b at the surface A spaced apart from the outer surface of the inner core 34. Subsequently, the first and second outer shell counterparts 32a and 32b are combined or joined at the surface A, disposing therein the inner core shell 34 equipped with the outer core shell 40 and spaced apart from the outer surface of the outer core 40. At this step, the inner core shell 34 is secured at its inlet portions 36 and its outlet portion 38 to the inner surface of the outer shell 32. Lastly, the flange portions 46a and 46b are respectively welded to the outer surfaces of the inlet and outlet portions 36 and 38. It will be understood that each counterpart of the outer shell 32, the outer core shell 40, and the inner core 34 may be formed of a metal sheet. 
     As best seen in FIG. 4, the outer shell 32, the inner core shell 34 and the outer core shell 40 are formed to decrease bent portions formed with sharp corners by totally rounding off, and accordingly local concentration of the thermal stresses is avoided improving the overall strength of the reactor 30. Additionally, portions adjacent the inlet portions 36 and the outlet portion 38 of the inner core shell 34 and the outer core shell 40 are gradually curved as shown and therefore they can easily be deformed to absorb the stresses generated by the radial and axial expansion between the inlet portions 36 and the outlet portion 38. 
     With the reactor of the configuration described above, if the temperature in the reactor 30 is raised to a high level by the oxidation reaction carried out in the reaction chamber 35 of the reactor 30, the reactor portions to which stresses are applied are easily deformed preventing local concentration of the stresses. This prevents the reactor 30 from thermal damage. Furthermore, since the inlet portions 36 and the outlet portion 30 are formed integral with the inner core 34, the gases in the reaction chamber 35 of the reactor 30 are prevented from leaking into the first insulation chamber 42 and to the insulating material in the second insulation chamber 44; conversely the insulating material is prevented from entering the reaction chamber 35. Accordingly, it will be understood that the thermal insulation of the reactor 30 is improved as compared with the prior art reactor shown in FIGS. 1 and 2, and consequently the oxidation reaction of carbon monoxide and hydrocarbons is effectively achieved accompanying improvement of the reaction efficiency. In addition, the reactor 30 of this configuration requires a decreased number of parts, allowing easy assembly of the reactor 30 compared with the prior art, because the reactor 30 according to the present invention does not require the slidable devices 26 employed in the prior art of FIGS. 1 and 2 and additionally it is constructed from integrally formed parts which are in the shape of generally half-splitted counterparts. This simplification in the construction contributes to make a reactor of light weight and of low production cost. 
     FIG. 5 illustrates another preferred embodiment of the reactor in accordance with the present invention, which reactor 30&#39; is similar to the reactor 30 of FIGS. 3 and 4 with the exception that the outer core shell 40 is removed to fill the insulating material (no numeral) between the inner core shell 34&#39; and the outer shell 32&#39;. Also in this case, the outer shell 32&#39; and the inner core shell 34&#39; are formed by combining the generally half-splitted counterparts at the line A&#39; similarly to the case of the FIGS. 3 and 4. 
     While only two embodiments have been shown and described, it will be understood that the principle of the present invention may be applied to reactors of other types.