Abstract:
A catalytic converter for the exhaust gas of an internal combustion engine has an internal by-pass structure in which the position of a bed temperature responsive valve determines whether inlet gas will flow through or around the catalyst bed.

Description:
BRIEF SUMMARY OF THE INVENTION 
     It is the purpose of the invention to provide an internal by-pass structure for a catalytic converter. 
     The invention accomplishes this purpose by means of an inlet chamber that receives all incoming exhaust gas and which has bed-flow and by-pass flow outlets controlled by a bed temperature responsive valve. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a horizontal cross section on a midplane through a catalytic converter embodying the invention, the converter being of the type disclosed and claimed in a copending U.S. application Ser. No. 234,009, filed Mar. 13, 1972, (now U.S. Pat. No. 3,809,539) of Robert N. Balluff and James D. Stormont, entitled &#34;Downflow Catalytic Converter, &#34; and assigned to the assignee hereof; 
     FIG. 2 is a vertical cross section on a midplane through the converter of FIG. 1; 
     FIG. 3 is a cross section along the line 3--3 of FIG. 2; and 
     FIG. 4 is an end elevation taken from the left or inlet side of the converter as shown in FIGS. 1 and 2. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The catalytic converter 1 has an oval outer shell 3 which is closed at opposite ends by an inlet header 5 and an outlet header 7, respectively, which are interlocked with it in fluid tight joints 9. Supported inside of the outer shell 3 is a slightly smaller oval inner shell 11 which has a bottom portion 12 that rests on the inside of the bottom of the outer shell 3 as seen best in FIG. 3. The inner shell is closed at opposite ends by a flanged inlet header 13 and a flanged outlet header 15 which are illustrated as welded inside the ends of the shell. Additionally, there is a flanged partition 17 welded inside the shell 11 adjacent the inlet header 13 and defining with it an inlet chamber 19. A catalyst bed 21 is defined inside the inner shell 11 by a transversely curved longitudinally extending bed support partition 23 which acts with a portion of the shell 11 (FIG. 3) to form the transversely downwardly curved shape of the bed. The opposite ends of the bed are closed by flanged partitions 25 and 27 which are welded to the bottom bed support 23. The bottom partition 23 and that part of the inner shell 11 located above it are louvered as seen at 29 and 31 to provide, respectively, outlet and inlet openings for gas to flow through the bed 21, the bed containing suitable particulate catalyst material. A capped filler tube 33 (FIG. 1) is supported in aligned necks 35 in header 5, header 13, partition 17, and partition 25 and opens at its inner end and outside of the converter to provide a means to refill the bed. 
     An inlet tube 37 for exhaust gas is supported in aligned necks 39 in inlet headers 5 and 13 to open into the inlet chamber 19. The inlet header 13 and the partition 17 have aligned flanged openings 41 and 43 providing seats for the valve heat 45 of a thermovalve member 47, the stem 49 of which is slidably supported in a bushing 51 mounted in the inlet header 5. Opening 41 permits flow through the bed 21 while opening 43 permits bypass flow around the bed. The outside end 53 of the stem 49 is operated through suitable circuitry and operating means 54 which includes means for sensing the temperature of bed 21, such as a thermister, and to the ignition circuit for the internal combustion engine. When the engine is off or when the temperature of the bed exceeds a predetermined temperature, e.g. 1800° F., the valve head 45 will seat on inlet header 13 to cover opening 41 and provide for bypass flow through opening 43. On engine start up or after the bed reaches a desired minimum temperature, the valve 45 will be shifted to seat on partition 17 and close opening 43 so that flow is through opening 41. 
     The space inside of inner shell 11 between the partition 17 and outlet header 15 comprises a combination bypass and bed outlet flow passage or chamber 55. The opening 43 connects it to inlet chamber 19 for bypass flow and the louvers 29 in partition 23 connect it to the bed 21 to receive outlet flow from the bed. The chamber 55 empties into an outlet tube 57, that is supported in aligned necks 59 in the outlet headers 7 and 15, which conducts gas out of the converter where ordinarily it enters a tailpipe (not shown) in the exhaust system. 
     The space inside of the outer shell 3 between it and the inner shell 11 comprises an inlet passage 61 connecting the opening 41 to the louvered openings 31 in inner shell 11 that form the inlet to bed 21. Thus, when the converter is operative and valve head 45 covers opening 43, inlet gas from inlet tube 37 enters inlet chamber 19, exits the chamber through opening 41, flows through space 61 to the bed inlet openings 31, passes through the catalyst in bed 21 where undesired emissions undergo chemical changes, and the treated gas leaves the bed through openings 29 in partition 23 to enter chamber 55 from which it leaves the converter via outlet tube 57. 
     When the converter is inoperative, the valve head covers opening 41 and inlet gas flows directly into chamber 55, bypasses the bottom of bed 21, and leaves the converter via outlet tube 57. 
     Modifications in the specific structure shown may be made without departing from the spirit and scope of the invention.