Catalytic converter with mid-bed sensor

A catalytic converter assembly is provided that includes a metallic tubular member having a first end and a second end. A first substrate is disposed within the metallic tubular. A second substrate is disposed within the metallic tubular member. A spacer is axially positioned the between the first and second substrate that includes a cylindrical body with a first wall and a second wall formed substantially perpendicular to the cylindrical body. The first wall abuts an end of the first substrate for retaining the first substrate between the first end and the first wall for preventing movement. The second wall abuts an end of the second substrate for retaining the second substrate between the second end and the second wall for preventing movement.

CROSS-REFERENCE TO RELATED APPLICATIONS

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BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates in general to catalytic converters, and more specifically, to catalytic converters with mid-bed sensor and short inlet and outlet substrates.

2. Background of Related Art

Catalytic converters include one or more catalytic elements housed in a metallic housing. The housing includes a first end and a second end. Each end portion may be conical-shaped. The catalytic converters are typically manufactured by cutting a metallic tubular member to a desired length. A respective support element is disposed around a respective substrate and thereafter inserted within the housing. The housing is formed to a targeted dimension for securing the substrates therein. One or more respective substrates may be utilized within a respective catalytic converter. Substrates are typically secured by some means to prevent movement of the substrate within the housing such as press forming the housing and support member against the outer surface of the substrate. Two substrates utilized in a catalytic converter disposed juxtaposed to one another are less susceptible to movement or tilting after the substrates are secured within the housing by deforming the housing radially inward. However, in certain instances, the substrates are required to be spaced from each other and may be subject to movement or tilting even though the housing and support member has been secured against the substrate.

One example is when a sensor is utilized. Sensors are commonly coupled to the housing for sensing gas concentrations passing through the substrates. The sensor is inserted through the wall of the housing and extends into the interior air space. The aperture for receiving the housing is typically disposed equidistant between the ends of the housing so that the sensor is positioned between the substrates.

Moreover, design constraints may dictate that the length of the converter is shorter than what is desired. Under such conditions, the axial length of the both substrates may be shortened to accommodate the shorter design packaging. The substrates will have a greater tendency to move and tilt as the axial length of each respective substrate gets substantially equal to or less than diameter of each respective substrate. The securing of the housing and support member against the substrates may not prevent movement or tilting of the respective substrates under such conditions. Therefore, there is a need to further secure the substrates when the substrates are spaced from one another in a catalytic converter assembly.

BRIEF SUMMARY OF THE INVENTION

The present invention has an advantage of utilizing a spacer that includes radial extending wall portions that abut the substrates in a catalytic converter. The wall portions provide an abutment surface against respective faces of the substrates to prevent movement or tilting of the substrate. The spacer may further include a plurality of apertures formed in the cylindrical body of the spacer if a sensor is utilized. The plurality of apertures provide for ease of assembly when an aperture in the housing of the catalytic converter is aligned with any one of the plurality of apertures of the spacer.

In one aspect of the present invention, a catalytic converter assembly is provided that includes a metallic tubular member having a first end and a second end. A first substrate is disposed within the metallic tubular member. A second substrate is disposed within the metallic tubular member. A spacer is axially positioned between the first substrate and the second substrate. The spacer has a cylindrical body with a first wall formed substantially perpendicular to the cylindrical body. The spacer further includes a second wall formed substantially perpendicular to the cylindrical body. The first wall abuts an end of the first substrate for retaining the first substrate between the first end and the first wall for preventing movement of the first substrate. The second wall abuts an end of the second substrate for retaining the second substrate between the second end and the second wall for preventing movement of the second substrate.

In yet another aspect of the present invention, a method is provided for forming a catalytic converter assembly having a first substrate and a second substrate. A metallic tubular member is provided having a first end and a second end. The metallic tubular member has an aperture formed centrally between the first end and the second end. A spacer is inserted within the metallic tubular member. The spacer has a cylindrical body with at least one aperture formed about the cylindrical body. The spacer further includes a first wall and a second wall formed substantially perpendicular to the cylindrical body. The first wall abuts an end of the first substrate for retaining the first substrate between the first end of the metallic tubular member and the first wall to prevent movement of the first substrate. The second wall abuts an end of the second substrate for retaining the second substrate between the second end of the metallic tubular member and the second wall to prevent movement of the second substrate. The aperture of the metallic tubular member is aligned with the at least one aperture of the spacer. A sensor boss is inserted through the aperture of the metallic tubular member aligned with the at least one aperture of the spacer. The first substrate is inserted through within the first end of the metallic tubular member. The second substrate is inserted within the second end of the metallic tubular member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, there is illustrated inFIG. 1, a cross section view of a catalytic converter assembly10. The catalytic converter assembly10includes a housing12formed from a corrosion resistant alloy such as a stainless steel alloy having a first end11and a second end13. The first end11and the second end13may include tapered or conical-shaped ends (not shown).

A first catalytic element14comprises a first substrate16and a first support member18secured within an interior of the housing12. An inner surface20of the housing1.2is pressed against the first catalytic element14for securing the first catalytic element14therein. Alternatively, the first catalytic element14may be stuffed into the housing12.

The catalytic converter assembly10further includes a second catalytic element21. The second catalytic element21comprises a second substrate22and a second support member19secured within an interior of the housing12. An inner surface20of the housing12is pressed against the second catalytic element21for securing the second catalytic element21therein. Alternatively, the second catalytic element21may be stuffed into the housing12.

The catalytic converter assembly10may further include a sensor boss24. The sensor boss24is inserted through a housing aperture28to the interior of the housing12. The sensor boss24receives a sensor (not shown) for measuring the gas concentrations passing through the substrates. Due to the spacing of the respective substrates, movement or tilting of the respective substrates may occur during operation of the catalytic converter, and more so when a shortened substrate (e.g., axial length substantially equal to or less than the diameter of the substrate) is utilized.

FIG. 2illustrates a cross section view of a catalytic converter assembly40according to a first preferred embodiment. The catalytic converter assembly40includes the first substrate16and the second substrate22. A first support member18is disposed between the inner surface20of the housing12and the first substrate16. A second support member19is disposed between the inner surface20of the housing12and the second substrate22. A spacer46is disposed between the first substrate16and the second substrate22, in addition to the first support member18and the second support member19.

FIG. 3illustrates a perspective view of the spacer46according to the first preferred embodiment. Referring to bothFIGS. 2 and 3, the spacer46includes a cylindrical body47having a first wall48and a second wall50. The spacer46is typically made from a thin-wall cut-off metallic tube such as a stainless steel pipe. The first wall48is formed substantially perpendicular to the cylindrical body47and extends radially inward from the cylindrical body47. The first wall48has a radial length that is greater than a thickness of the cylindrical body.

The second wall50is formed substantially perpendicular to the cylindrical body47and extends radially inward from the cylindrical body47. The second wall50has a radial length that is greater than a thickness of the cylindrical body47.

The first wall48and the second wall50are flat planar surfaces that abut a portion of a face of the first substrate16and a portion of the second substrate22, respectively. The first wall48and the second wall50are added due to the difficulties that are present in controlling the spacer size to match the substrates. That is, if a respective spacer were utilized that did not include a first wall48and a second wall50, and if the respective spacer is sized is too large, then the respective substrates may slip into the respective spacer. Alternatively, if the respective spacer were too small, then a thin-walled spacer may cause a very high concentrative stress on the face of the respective substrates and damage the respective substrates, which are typically made of ceramic. If respective spacer is out-of-round, then those portions of the respective spacer that is too large will allow the respective substrates to slip within the respective spacer while other portions of the respective substrate will be blocked by the decreased spacer diameter as a result of the out-of-roundness profile. By utilizing the spacer46having the first wall48and the second wall50, the areas of the first substrate16and the second substrate22contacting the first wall48and the second wall50are dispersed over a larger area than those very high concentrated areas of contact discussed above. As a result, the first substrate16and the second substrate22are less susceptible to damage resulting from spacer46vibrating against the first substrate16and second substrate22as a result of operational vibration since the spacer46secures the first substrate16and the second substrate against the first end11and the second end13, which prevents movement or tilting.

As shown inFIG. 3, a plurality of apertures52is formed about the cylindrical body47of the spacer46. The plurality of apertures52allows the spacer46to be inserted within the housing12without having to maintain radial alignment with the aperture28of the housing12during assembly. As the spacer46is inserted within the housing12, at least one of the plurality of apertures52will be partially aligned with the aperture28of the housing12. That is, after assembly of the spacer46, a portion of one of the plurality of apertures52will be visible through the aperture28of the housing12such that the spacer46can be slightly rotated so that full alignment between the respective apertures may be attained.

FIGS. 4 and 5illustrate the formation of the spacer46according to the first preferred embodiment. A thin-wall cut-metal tubular member53is placed into a roll forming tool54. A first forming member56is inserted through the interior region of the tubular member53. The first forming member56is brought into contact with an inner surface57of the tubular member53. A second roll forming member58is brought into contact with an outer surface59of the tubular member53. Both the first forming member56and the second forming member58are rotated. As the second roll forming member58is urged against the outer surface59of the tubular member53, each end of the tubular member53are shaped for forming the first wall48and the second wall50between the first roll forming member56and second roll forming member58in a direction that is substantially perpendicular to the cylindrical body47of the spacer46. The first wall48and the second wall50extend radially inward from the cylindrical body47.

FIG. 6illustrates a cross section view of a catalytic converter assembly60according to a second preferred embodiment. The spacer61is similar to the spacer46shown inFIGS. 2 and 3with the addition of curled ends. The first wall48includes an inner race end portion62that is curled axially inward. The second wall50includes an inner race end portion64that is curled axially inward. Since the spacer61is formed from a cut-off metal tube, the end portions may have sharp edges or burrs which can protrude into the respective substrates. Curling the respective end portions62and64axially inward away from their respective adjacent substrates prevent damage that may be the result of a sharp edge projecting into a respective face of each substrate.

FIG. 7illustrates a perspective view of the spacer70according to a third preferred embodiment. The spacer70includes the cylindrical body72having a first wall74and a second wall76. The first wall74and the second wall76are formed such that the respective flanges extend radially outward in comparison to the flanges of the respective spacer shown inFIG. 3. In addition, the plurality of apertures52are coupled to a plurality of projecting tubular bosses78for creating guided supports. Preferably, the plurality of projecting tubular bosses78is coupled to the plurality cylindrical body72of the spacer70such that each respective aperture is axially aligned with a respective projecting tubular boss.

FIG. 8illustrates a cross section view of a catalytic converter assembly71according to the third preferred embodiment. The spacer70is disposed between the first substrate16and the second substrate22. The spacer70has an inner surface diameter72that is smaller than the diameter of the spacer46shown inFIGS. 2 and 3which allows space for the first wall74and the second wall76, in addition to the plurality of projecting tubular bosses78to extend in a direction toward the inner surface of the housing12. The sensor boss24is received within the plurality of projecting tubular bosses78extend radially outward within the housing12. As the spacer70is inserted within the housing12, at least one of the plurality of projecting tubular bosses78will be partially aligned with the aperture28of the housing12. The respective projecting tubular boss partially aligned, if not fully aligned, will be visible through the aperture28of the housing12such that the spacer70can be slightly rotated so that full alignment between the respective aperture and the respective projecting tubular boss may be attained.