BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross section view of catalytic converter assembly according to a first preferred embodiment.
FIG. 2 is a perspective view of a tubular member having catalytic elements formed therein according to a first preferred embodiment.
FIG. 3 is a cross section view of a plurality of neck portions formed by a spin forming operation according to a first preferred embodiment.
FIG. 4 is a cross section view of a sectioned tubular member for forming catalytic converters according to a first preferred embodiment of the present invention.
FIG. 5 is a side view of the forming tool and the catalytic converter according to a first preferred embodiment of the present invention.
FIG. 6 is a section view of a catalytic element and the indentation formed therein according to a first preferred embodiment of the present invention.
FIG. 7 is a cross section view illustrating discrete forming locations spin forming process according to a first preferred embodiment of the present invention.
FIG. 8 is a flowchart of a method for forming the catalytic converter according to a first preferred embodiment of the present invention.
FIG. 9 is a flowchart of a method for forming a plurality of catalytic converters according to a first preferred embodiment of the present invention.
FIG. 10 is a cross section view illustrating the contour path of the forming tool for continuous spin forming process according to a second preferred embodiment of the present invention.
FIG. 11 is a side view of the forming tool and the catalytic converter according to a third preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, there is illustrated in FIG. 1, a cross section view of the inventive catalytic converter assembly 10. The catalytic converter assembly 10 includes a housing 12 formed from a corrosion resistant alloy such as a stainless steel alloy.
The catalytic converter assembly 10 further includes a first catalytic element 14 and a second catalytic element 15 each comprising a substrate and a support material secured within an interior of the housing 12. Alternatively, the catalytic converter assembly 10 may include only one catalytic element or more than two catalytic elements. An inner surface 16 of the housing 12 is pressed against the first catalytic element 14 and the second catalytic element 15 for securing the first catalytic element 14 and second catalytic element from radial movement therein. An indentation 17 is formed between the first catalytic element 14 and the second catalytic element 15 for preventing axial movement of the first catalytic element 14 and the second catalytic element 15 within the housing 12.
The catalytic converter assembly 10 includes a first conical-shaped end 18 having a first port 20. The first port 20 is coupled to an exhaust pipe of a vehicle (not shown) extending from an internal combustion engine of the vehicle(not shown). The catalytic converter assembly 10 further includes a second conical-shaped end 22 having a second port 24. The second port 24 is coupled to a next portion of the exhaust system (not shown).
The first port 20 functions as an inlet port for receiving exhaust gases from the internal combustion engine such has hydrocarbons, carbon monoxide, and nitrogen oxides and converts the exhaust gases into carbon dioxide, water, nitrogen, and oxygen. The second port 24 functions as an exhaust port for discharging the converted gases to the discharging portion of the exhaust system (not shown).
FIG. 2 illustrates a tubular member 26 used to form the housing 12 of the catalytic converter assembly 10. The tubular member 26, as stated earlier, is a non-corrosive metallic housing and includes an outer surface 30 of an initial uniform diameter. The tubular member 26 is typically formed from a single strip of sheet metal. The sheet metal strip is wrapped length-wise and is welded along a seam for forming the tubular member 26. Alternatively, the tubular member 26 may be formed as a seamless tubular member by another process such as an extrusion process. The length of the tubular member 26 is preferably such that two or more housings may be produced from the tubular member 26.
A plurality of catalytic elements 31 are assembled into the interior of the tubular member 26. Preferably, the plurality of catalytic elements 31 are assembled in pairs such that each of the catalytic elements comprising a respective pair (e.g., first catalytic element 14 and second catalytic element 15) are spaced in close relation to one another. Each respective pair of catalytic elements are spaced at a predetermined distance from an adjacent pair of catalytic elements to allow respective conical-shaped ends to be formed on each side of a respective pair of catalytic elements. Alternatively, the catalytic elements may be equally spaced from one another so that a respective catalytic converter only includes a single catalytic element.
FIG. 3 illustrates a plurality of neck portions formed in the tubular member 26 which are used to create respective conical-shaped ends for each respective housing section of the catalytic converter 10. A spin forming machine, shown generally at 32, having at least one forming wheel, is brought into contact with the outer surface 30 of the tubular member 26. In the preferred embodiment, the tubular member is rotated as the at least one forming wheel is brought into contact with the outer surface 30 for shaping the tubular member 26. The at least one forming wheel is moved both axially and radially along the rotating tubular member 26 for forming a plurality of neck portions 34. An alternative process may include only the at least one forming wheel being rotated about the tubular member 26 for forming the plurality of neck portions 34 while the tubular member 26 remains unrotated. In yet another alternative process, both the at least one forming wheel and the tubular member 26 are simultaneously rotated for forming the plurality of neck portions 34. Each of he neck portions 34 include a pair of opposing conical-shaped sections 36 and 38 integrally connected by a substantially uniform cylindrical bridge section 40 such that a respective diameter at any given location of the neck portion 34 is smaller than the initial diameter of the tubular member 26. Multiple neck portions may be formed by the forming tool 32 at predetermined axial locations for creating a plurality of catalytic converters from a respective single tubular member. Preferably, each neck portion is aligned about a same axis as the tubular member 26 from which it was formed. Alternatively, each neck portion may be formed so that the axis of each neck portion is different than the axis of the tubular member 26.
FIG. 4 illustrates the tubular member 26 sectioned into a plurality of catalytic converters. The tubular member 26 is separated by a transverse cut at substantially an axial midpoint 40 of each neck portion 34 for forming the plurality of catalytic converters. Separation of the tubular member at the respective axial midpoints of each respective neck portion may be performed by a cutting operation such as a laser cut, a saw-cut, or a plasma cut. Other-cutting operations may include a milling operation (e.g., high speed milling operation) for separating the respective pre-forms. Material from one or both of the ends of the catalytic converter 10 may be removed to accommodate a desired length.
FIG. 5 illustrates the tubular member being formed by the spin forming machine 32. The tubular member 26 is de-formed by the spin forming machine 32 utilizing a first forming wheel 42 and a second forming wheel 44. The first forming wheel 42 and the second forming wheel 44 are spaced equidistant (i.e., equal radial spacings) about the tubular member 26 for applying a counterbalanced force to the outer surface 30 when shaping the tubular member 26. Applying an equal force from opposite directions equalizes the force exerted on the tubular member 26 which improves the conical-shaped end forming process by reducing bending stress and distortion on the tubular member 26. As a result, the tubular member 26 is better supported during the forming process and a lower clamping force is required for retaining the tubular member 26 within the spin forming machine 32 while exerting a force from the multiple forming wheels. Cycle time for shaping each of the respective regions of the tubular member 26 is reduced since less passes are required to form the respective regions. With the reduction of cycle time, production output is increased. In addition, as a result of the multiple forming wheels, each of the respective regions of the tubular member 26 can be shaped without having to unload and remount the tubular member 26 in the same or different spin forming machine which allows for the elimination of multiple spin forming machines. Lastly, since the neck portions are formed prior to cutting the tubular member, less material is required to be cut in the narrowed neck portion, and as a result, the tubular members may be cut faster and less (cutting) tooling wear is achieved.
FIG. 6 illustrates the catalytic converter 10 having a midsection indentation for preventing axial movement of the catalytic elements 14 and 15 within the catalytic converter 10. An indentation 17 is formed in a midsection wall of the catalytic converter 10 between the first catalytic element 14 and the second catalytic element 15 by applying a force to the outer surface 30 by the first spin forming wheel 42 and the second spin forming wheel 44. When applying the force to the midsection wall of the catalytic converter 10 for forming the indentation 17, the force from the spin forming wheels 42 and 44 is counterbalanced (i.e., there is zero net force in each direction).
To prevent radial movement of the first catalytic element 14 and the second catalytic element 15 within the catalytic converter 10, the first and second spin forming wheels 42 and 44 apply a force to the outer surface 30 that is axially aligned (i.e., radially overlapping) with the first catalytic element 14 and the second catalytic element 15 for securing the inner wall 16 against the respective catalytic elements. This may include an indentation (similar to the indentation 17 used to prevent axial movement) to secure the first catalytic element 14 and the second catalytic element to prevent radial movement. This may be performed prior to or after the formation of the indentation 17. Alternatively, forming the indentation 17 and securing the catalytic elements to the inner surface 16 may be performed either before the tubular member 26 is separated into various catalytic converter assemblies or after the tubular member is separated into the respective catalytic converter assemblies; however, forming afterwards requires each respective catalytic converter assembly be reloaded into a spin forming machine.
FIG. 7 illustrates the tubular member 26 of the catalytic converter 10 being shaped by a discrete spin forming process which shapes discrete regions of the tubular member 26 in a non-continuous operation. That is, the forming tools 42 and 44 discretely move (e.g., slide longitudinally) to various regions of outer surface 30 of the tubular member 26 for forming the respective regions as opposed to continuously moving over the entire surface from a first end to a second end. For example, the region of the tubular member 26 overlapping the first catalytic element 14 may be shaped first. The forming tools will pass over this section one or more times for shaping this respective region. The forming tools 42 and 44 will then advance to a region of the tubular member 26 overlapping the second catalytic element 15 and shape this respective region. Thereafter, the forming tools 42 and 44 advances to the first end of the tubular member for shaping the first conical-shaped end 18, and subsequently, to the second end of tubular member where the second conical-shaped end 22 may be formed. Finally the forming tools 42 and 44 advance to the respective midsection where the indentation 17 is formed. In the discrete forming-operation, the various respective regions of the outer surface may be shaped in any order that the manufacturer desires.
FIG. 8 is a flowchart of a method for forming a catalytic converter assembly. In functional block 60, a tubular member is provided for forming a housing of a catalytic converter assembly. The tubular member may be a seamless single piece tube or may be a sheet metal strip that is wrapped and welded along a seam.
In functional block 61, at least one catalytic element is inserted in the tubular member.
In functional block 62, an end of the tubular member is mounted in the spin forming machine having at least two spin forming wheels for forming the tubular member.
In functional block 63, a force is applied to a first end section of the tubular member by the at least two spin forming wheels for forming the first conical-shaped end. The at least two spin forming wheels are spaced equally around the tubular member for evenly supporting the tubular member and to apply an equal distribution of force when shaping the tubular member.
In functional block 64, a force is applied to a second end section of the tubular member by the at least two spin forming wheels for forming the second conical-shaped end. Since the at least two spin forming wheels are spaced equidistant around the tubular member for applying the equal distribution of force, the tubular member does not require additional support for the second end of the tubular member despite its overall length since support is provided by the at least two spin forming wheels.
In functional block 65, a force is applied by the at least two spin forming wheels to the outer surface of the tubular member between the conical-shaped ends to prevent axial movement of the at least one catalytic element within the catalytic converter.
In functional block 66, a force is applied to the outer surface of the tubular member of a region overlapping the at least one catalytic element for securing the at least one catalytic element within the catalytic converter and preventing radial movement of the catalytic elements. This force applied to the outer surface may produce an indentation to a portion of the overlapping region or the entire region overlapping the at least one catalytic element may be deformed for securing preventing radial movement.
FIG. 9 illustrates a flowchart for a method for forming a plurality of catalytic converter assemblies. In functional block 70, a tubular member is provided for forming a plurality of catalytic converter assemblies. The tubular member has predetermined overall length which allows for the manufacture of multiple housings to be used to manufacture and assemble the plurality of catalytic converter assemblies.
In functional block 71, a plurality of catalytic elements are inserted in the tubular member. The plurality of catalytic elements are grouped in pairs so that the axial spacing between a designated pair of catalytic elements is less that the axial spacing between adjacent pairs of catalytic elements. This allows for a sufficient amount of material to be provided between the adjacent pairs of catalytic elements for forming the neck portions.
In functional block 72, an end of the tubular member is mounted in the spin forming machine having at least two spin forming wheels for forming the tubular member. The at least two spin forming wheels are spaced equally around the tubular member for applying an equal distribution of force at each contacting location and for evenly supporting the tubular member.
In functional block 73, a force is applied by the at least two spin forming wheels to respective sections on the outer surface of the tubular member that overlap the catalytic elements for securing the catalytic elements within the catalytic converter and preventing radial movement of the catalytic elements.
In functional block 74, a force is applied by the at least two spin forming wheels to respective sections of the outer surface located between adjacent pairs of catalytic elements for forming a plurality of neck portions.
In functional block 75, a force is applied by the at least two spin forming wheels to respective regions of the outer surface located between a respective pair of catalytic elements for forming an indentation therebetween for preventing axial movement of the catalytic elements within the catalytic converter.
In functional block 76, separating the tubular member at substantially the axial midpoint of each neck portion for forming a plurality of catalytic converters.
FIG. 10 illustrates an alternative method of shaping the outer surface of the tubular member. In contrast to the discrete spin forming operation shown in FIG. 7, the housing 12 of the catalytic converter 10 is formed in a single continuous forming operation. A contour-shape of the outer surface 30 of the catalytic converter 10 is shown generally by the dotted off-set contoured line 46. The contour-shape is produced by the first forming wheel 42 and second forming wheel 44 advancing longitudinally in a continuous forming operation. That is, the entire housing 12 between the ends the catalytic converter 10 are formed in a continuous forming operation without lifting the forming wheels 42 and 44 from the outer surface of the tubular member 26. The forming wheels 42 and 44 will contact the tubular member 26 at a respective end to form the first conical-shaped end 18. The forming wheels 42 and 44 will maintain continuous contact with the outer surface 30 thereafter to depress the region of the outer surface 30 over first catalytic element 14, the indentation 17, the region of the outer surface 30 over the second catalytic element 15, and the second conical-shaped end 22.
FIG. 11 illustrates an alternative embodiment for a spin forming machine having multiple forming wheels. A forming tool 48 includes a first forming wheel 50, a second forming wheel 52, and a third forming wheel 54. The forming wheels are positioned at equal radial spacings about the tubular member 26. In addition, each of the forming wheels applies a balanced force to the tubular member 26 when shaping the tubular member 26. The three respective forming wheels equally support the tubular member 26 during the spin forming operation so that tighter manufacturing tolerances of the finished catalytic converter may be produced. In addition, the multiple forming wheels reduce the number of times the forming wheels must pass over a respective section for shaping a respective region. This reduces manufacturing time as well as tool wear.
In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope. For example, the steps of shaping each of the respective regions of the catalytic converter may interchanged such that one region may be formed before other regions. In addition, the tubular member may be separated prior to inserting the catalytic elements and spin forming each respective tubular section for shaping each catalytic converter.
Patent Application
20080000084
