CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation-in-part of U.S. Application No. 14/708,329, filed May 11, 2015.

TECHNICAL FIELD

[0002] The subject invention relates to a method and apparatus for sizing an exhaust component shell having at least two different diameters. More specifically, the subject invention relates to sizing a converter shell having a sensor hole located between shell portions that may have different diameters.

BACKGROUND OF THE INVENTION

[0003] A vehicle exhaust system includes various components that conduct exhaust gases generated by a combustion engine to an ambient outlet. One such exhaust component is a catalytic converter that includes an outer shell defining an internal cavity that receives one or more catalyst substrates. The catalyst substrate can be formed as a single piece or can be separated into multiple pieces which are referred to as "bricks." Typically, the substrates are wrapped with an insulating material, e.g. an insulation mat, to reduce heat radiation to adjacent components in a vehicle underbody, and to retain or support the substrate in the shell.

[0004] During vehicle operation, sensors are often used to monitor certain catalytic converter characteristics. For example, the catalytic converter often includes an oxygen sensor. The oxygen sensor is attached to a sensor boss that is installed on the outer shell. In one known configuration, the sensor boss is attached to an outer shell that surrounds a pair of substrates received within the internal cavity.

[0005] Typically, the method for manufacturing this type of converter configuration includes measuring the substrates, weighing the mats, wrapping the mats around the substrates, and inserting the wrapped substrates into a cylindrical outer shell. The shell is then sized, such as by reducing a diameter of the shell, to a desired diameter based on the measured substrate and mat weight characteristics. Prior to the stuffing step, at least one hole is typically punched into the outer shell at a location between the substrates, and a sensor boss is attached to surround this hole after the sizing process is completed. Typically, the sensor boss is welded to the outer shell about the hole location.

[0006] In certain configurations, the outer shell may have to be sized to two different diameters to compensate for component tolerance variation. For example, one end of the shell that surrounds one substrate may be required to be sized to a smaller diameter than an opposite end of the shell that surrounds the other substrate. Traditional sizing operations for this type of configuration provide a poor weld area around the sensor hole. The differing diameters can result in large gaps between the boss and the shell at discrete circumferential locations, which is undesirable.

SUMMARY OF THE INVENTION

[0007] In one exemplary embodiment, a method for forming an exhaust component includes providing at least a first substrate and a second substrate; providing an outer shell that surrounds the first and second substrates, the outer shell defining a center axis; forming at least one sensor hole in the outer shell at a location between the first and second substrates; and surrounding a first end of the outer shell with a first plurality fingers to size the first end around the first substrate to a first diameter, wherein the first plurality of fingers includes at least one extended finger that is longer than the other fingers such that the extended finger at least partially covers the sensor hole during sizing of the first end.

[0008] In a further embodiment of the above, the method includes surrounding a second end of the outer shell with a second plurality of fingers to size the second end around the second substrate to a second diameter, wherein the second plurality of fingers includes at least one recessed finger that is aligned with the at least one extended finger during sizing of the second end.

[0009] In a further embodiment of any of the above, the method includes sizing the first end and the second end simultaneously until one of the first or second diameters for the associated first or second end is achieved, and wherein sizing continues for the other of the first or second ends until the other of the first or second diameters is achieved.

[0010] In a further embodiment of any of the above, the at least one extended finger comprises a first finger body extending to a first distal end having a protruding tip and the at least one recessed finger comprises a second finger body that extends to a second distal end having a recess generally corresponding in shape to a shape of the protruding tip, and the method includes receiving the protruding tip within the recess during sizing of the first and second ends.

[0011] In another example embodiment, a method for forming an exhaust component includes providing at least a first substrate and a second substrate; providing an outer shell that surrounds the first and second substrates, the outer shell defining a center axis; forming at least one sensor hole in the outer shell at a location between the first and second substrates; surrounding a first end of the outer shell with a first plurality fingers to size the first end around the first substrate to a first diameter, wherein the first plurality of fingers includes at least one first finger having a protruding tip that is longer than the other fingers of the first plurality of fingers such that the protruding tip at least partially covers the sensor hole during sizing of the first end; and surrounding a second end of the outer shell with a second plurality of fingers to size the second end around the second substrate to a second diameter, wherein the second plurality of fingers includes at least one second finger having a recessed tip within which the protruding tip is received during sizing of the first and second ends.

[0012] In a further embodiment of any of the above, the method includes attaching one or more sensor bosses to the outer shell at the sensor hole.

[0013] In another exemplary embodiment, an apparatus is provided for sizing an exhaust component having an outer shell defining a center axis extending from a first shell end to a second shell end, a first substrate positioned within the internal cavity at the first shell end, a second substrate positioned within the internal cavity at the second shell end, and at least one sensor hole formed in the outer shell between the first and second substrates. The apparatus includes a plurality of first fingers to surround the first shell end to size the outer shell about the first substrate to a first diameter, and wherein each first finger of the plurality of first fingers extends in an axial direction and are circumferentially spaced apart from each other about the central axis; and wherein the plurality of first fingers extend to a first finger distal end, and wherein at least one first finger has a protruding portion at the first finger distal end that is longer than the first finger distal end of the other first fingers.

[0014] In a further embodiment of any of the above, the apparatus includes a plurality of second fingers to surround the second shell end to size the outer shell about the second substrate to a second diameter, and wherein the plurality of second fingers extend in an axial direction and are circumferentially spaced apart from each other about the central axis; and wherein each second finger of the plurality of second fingers extends to a second finger distal end, and wherein at least one second finger has a recess portion at the second finger distal end that receives the protruding portion.

[0015] In another example embodiment of any of the above, when the plurality of first fingers surround the first shell end, the protruding portion at least partially covers the at least one sensor hole.

[0016] In another example embodiment of any of the above, the recess portion comprises a curved indentation, and wherein the protruding portion comprises a rounded tip that covers the sensor hole and extends into the curved indentation when the first and second substrates are sized to the first and second diameters.

[0017] These and other features may be best understood from the following drawings and specification.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic representation of a vehicle exhaust system with a catalytic converter incorporating the subject invention.

[0019] Figure 2 is a schematic representation of the catalytic converter including two substrates and an outer shell sized to two different diameters.

[0020] Figure 3 is a schematic representation of a sensor hole formed in the outer shell at a location between the two substrates.

[0021] Figure 4 is schematic representation of a tool used to size the outer shell.

[0022] Figure 5 is a perspective view of the tool showing a plurality of fingers including one extended finger.

[0023] Figure 6 is a top view of a distal end of the extended finger in relation to the sensor hole.

[0024] Figure 7 is a perspective view of another example of a tool used to size the outer shell.

[0025] Figure 8 is a schematic section view showing the tool and outer shell of Figure 7

[0026] Figure 9 is a view similar to Figure 8 but including the two substrates. [0027] Figure 10 is a top view of a distal end of the extended finger of the tool from Figure 7 in relation to the sensor hole.

[0028] Figure 11 is an example showing a substrate with an oval cross-section.

[0029] Figure 12 is an example showing a cross section of shell having more than one sensor hole at a location between substrates.

DETAILED DESCRIPTION

[0030] Figure 1 shows a vehicle exhaust system 10 that conducts hot exhaust gases generated by an engine 12 through various upstream exhaust components 14 to reduce emission and control noise as known. The various upstream exhaust components 14 can include one or more of the following: pipes, filters, valves, catalytic converters, mufflers etc. In one example configuration, the upstream exhaust components 14 direct exhaust gases into a catalytic converter 16 having an inlet 18 and an outlet 20. The outlet 20 communicates exhaust gases to downstream exhaust components 22. The various downstream exhaust components 22 can include one or more of the following: pipes, filters, valves, mufflers etc. These upstream 14 and downstream 22 components can be mounted in various different configurations and combinations dependent upon vehicle application and available packaging space.

[0031] As shown in Figure 2, the converter 16 has an outer shell 24, also referred to as a can, which defines an internal cavity 26. In the example shown in Figure 2, the catalytic converter 16 includes at least a first substrate 28 and a second substrate 30. The catalyst substrates 28, 30 are received within the internal cavity 26. As known, the catalyst substrate is a substance that speeds up a chemical reaction rate. In an automotive exhaust application, the catalyst substrate comprises an inert substance onto which an active wash coat is added. The catalyst substrate speeds up oxidation of unconverted hydrocarbons, carbon monoxide, and nitrogen oxides into water, carbon dioxide, and hydrogen. The materials used for the inert substance and active wash coat, and the operation of a catalytic converter is well known and will not be discussed in further detail.

[0032] A first mat 32 surrounds the first substrate 28 and a second mat 34 surrounds the second substrate 30. The mats 32, 34 are compressed between the outer shell

24 and the respective substrates 28, 30 during sizing of the outer shell 24, which will be discussed in greater detail below. The outer shell 24 includes an external surface 36 and an internal surface 38 that defines the internal cavity 26. The mats 32, 34 are compressed directly against the internal surface 38, and provide insulation and help reduce noise. Any type of insulating mat material known in the art could be used for mats 32, 34. The mats 32, 34 are preferably wrapped around the catalyst substrates 28, 30.

[0033] The outer shell 24 defines a central axis A that extends from a first end 40 to a second end 42. In an area 44 on the outer shell 24 at a location between the first 28 and second 30 substrates, at least one sensor hole 46 (Figure 3) is formed. In the example shown, the sensor hole 46 has a circular shape. However, any other hole shapes could also be used such as oval, square, rectangular, etc.

[0034] A sensor boss 48 is attached to the outer shell 24 and extends outwardly from the external surface 36. Typically, the sensor boss 48 (Figure 11) is welded directly to the outer shell 24. The sensor boss 48 can be used for any type of exhaust sensor; however, the sensor boss 48 is preferably used for an oxygen sensor (not shown). The exhaust sensors are used to measure and monitor catalytic converter operating characteristics as needed. The operation of exhaust sensors, such as an oxygen sensor, is well-known and will not be discussed in further detail.

[0035] In one example configuration, the first end 40 of the outer shell is sized to a first diameter Dl around the first substrate 28 and the second end 42 is sized to a second diameter D2 around the second substrate 30 where the second diameter D2 is greater than the first diameter Dl. The sensor hole 46 is formed by a punching operation, for example, prior to the stuffing the first 40 and second 42 ends. Typically, the area 44 in which the hole 46 is formed has a very short axial length between the two substrates 28, 30. In such a configuration, this area 44 around the sensor hole 46 will deform to a certain extent during the sizing operations resulting in different diameters on opposite sides of the hole 46. This makes it difficult to weld the sensor boss 48 to the outer shell 24. Often, a large gap will be formed at one side of the hole 46 which is undesirable. The subject invention provides a method and apparatus for sizing the outer shell 24 to provide a better welding area around the sensor hole 46.

[0036] As discussed above, the outer shell 24 surrounds the first and second substrates 28, 30, which are wrapped in the first 32 and second 34 mats, respectively. The substrates 28, 30 can have variable diameters and the mats 32, 34 can have variable weights.

In the example shown, the first substrate 28 has a first substrate diameter D3 and the second substrate has a second substrate diameter D4 greater than the first substrate diameter D3. The diameters D3 or D4 could be the same with varying dimensions possibly caused by differences in the mats 32, 34. Further, any difference that does exist between the diameters D3, D4 is very small due to component tolerance variation. The difference is exaggerated as schematically shown in Figure 1 solely for discussion purposes.

[0037] The degree of sizing of the first 40 and second 42 ends is determined based on characteristics of the components located within the outer shell 24. For example, these characteristics can be related to specific component characteristics of the substrates and/or mats, or of other components located within the outer shell. In one example, the diameter of the substrates and the weight of the mats is used. This example is described in greater detail below.

[0038] In one example method of manufacturing the converter 16, the sensor hole 46 is formed in the outer shell, the diameters of the substrates 28, 30 are measured, and the mats 32, 34 are weighed. After, these steps are taken, the first mat 32 is wrapped around the first substrate 28 and the second mat 34 is wrapped around the second substrate 30. Next, the wrapped substrates 28, 30 are stuffed into the outer shell 24. The shell 24 has at least one sensor hole 46 punched into the shell 24 at a location between the substrates 28, 30 prior to the stuffing step.

[0039] A first end 40 of the shell 24 is then sized to the first diameter Dl based on the measured diameter of the first substrate 28 and the weight of the first mat 32. The first end 40 refers to the portion of the outer shell 24 that surrounds at least the first substrate 28.

[0040] As shown in Figures 4-6, the sizing process utilizes a sizing tool 50 having a base 52 coupled to an actuator 54. A plurality of circumferentially spaced fingers 56 extend outwardly from the base 52. At least one of the fingers 56a is longer than the remaining fingers 56. In the preferred configuration, only one extended finger 56a is longer than the remaining fingers 56. This extended finger 56a is aligned to extend over and at least partially cover the sensor hole 46 during the sizing process for the first end 40. This provides a surface around one side of the hole 46 that is sized to the first diameter Dl. During the sizing process, the actuator 54 moves the fingers 56 radially inwardly toward the center axis A to apply a compressive force F to reduce the outer shell 24 to the specified first diameter Dl. Operation of the sizing tool to reduce the outer shell to the desired size is well known and will not be discussed in further detail. [0041] Once the first end 40 has been sized to the first diameter Dl, the shell 24 is removed from the tool 50 and the entire assembly is then flipped around for the second sizing process. The second end 42 of the shell 24 is then surrounded by the fingers 56 and is sized to the second diameter D2 based on the measured diameter of the second substrate 30 and weight of the second mat 34. The second end 42 refers to the portion of the outer shell 24 that surrounds at least the second substrate 30. The extended finger 56a is aligned to extend over and at least partially cover the sensor hole 46 during the second sizing process. This provides a surface around an opposite side of the hole 46 that is sized to the second diameter D2, which is greater than the first diameter Dl. During the sizing process, the actuator 54 moves the fingers 56 radially inwardly toward the center axis A to reduce the outer shell 24 to the specified second diameter D2.

[0042] In another example, the plurality of fingers could comprise a first set of fingers and a second set of fingers, with each of the first and second sets of fingers including at least one extended finger 56a. As such, one set of fingers as shown in Figure 5 would be positioned at one end of the shell 24 and another set of fingers as shown in Figure 5 would be positioned at an opposite end of the shell 24. The first end 40 of the outer shell is sized to the first diameter Dl with the first set of fingers, and the second end 42 of the outer shell is sized to the second diameter D2 with the second set of fingers. This embodiment may increase tooling costs as two separate sets of fingers would be required, however, the step of flipping the outer shell around would be eliminated.

[0043] In the example shown, as the diameter of the second sizing is greater than the first sizing, the extended finger 56a does not contact the side of the hole 46 that was sized to the first diameter Dl resulting in less deformation. Finally, the sensor boss 48 is then welded to surround the sensor hole 46. The area around the hole 46 still has two different diameters; however, the surface has a better shape for welding than with traditional sizing operations.

[0044] The fingers 56 extend axially from the base 52 and are circumferentially spaced apart from each other about the central axis A. The fingers 56 are defined by an axial length LI that extends from the base 52 to a distal finger end 58. In one example, the axial length LI extends to a location that is generally at a center of the hole 46. The extended finger 56a has a longer axial length L2 than the other fingers 56. In one example, the longer axial length L2 is configured to extend past the hole 46 by a predetermined minimal length such as 5 mm, for example. The predetermined minimal length will vary dependent upon the converter configuration, size of the substrates, and weight of the mats.

[0045] In one example, the distal finger end 58 includes a tip portion 60 that extends beyond the distal end 58 to completely cover the hole 46. This shape of the tip portion 60 can vary. In the example shown, the fingers 56 are all defined by a common width Wl in a circumferential direction. In one example, the tip portion 60 includes a rounded portion that does not extend over the entire width Wl of the extended finger 56a. In another example, the tip portion 60 could be rounded along the entire width. The extended portion comprising the difference in axial length (L2-L1) comprises a circumferential area surrounding a portion of the hole 46. This provides a process that does not adversely deform the sensor hole 46, and which does not result in too much pressure being applied to the mats 32, 34. Having only one finger 56a extend past the hole 46, as opposed to all fingers extending past, creates a better welding area around the hole 46 and less deformation, as well as avoiding over compression of the mat.

[0046] Figures 7-10 show another example method and apparatus for sizing an outer shell around a pair of substrates. In this example, an outer shell 124 defines an internal cavity 126 that includes at least a first substrate 128 and a second substrate 130. A first mat 132 surrounds the first substrate 128 and a second mat 134 surrounds the second substrate 130. The mats 132, 134 are compressed between the outer shell 124 and the respective substrates 128, 30 during sizing of the outer shell 124, in a manner as discussed above. The outer shell 124 includes an external surface 136 and an internal surface 138 that defines the internal cavity 126. The mats 132, 134 are compressed directly against the internal surface 38, and provide insulation and help reduce noise.

[0047] The outer shell 124 defines the central axis A that extends from a first end 140 to a second end 142. In an area 144 on the outer shell 124 at a location between the first 128 and second 130 substrates, at least one sensor hole 146 (Figure 7) is formed. In the example shown, the sensor hole 146 has a circular shape. However, any other hole shapes could also be used such as oval, square, rectangular, etc. A sensor boss is attached to the outer shell 124 and extends outwardly from the external surface 136 as described above.

[0048] The substrates 128, 130 can have variable diameters and the mats 132, 134 can have variable weights as described above. Also, as discussed above, degree of sizing of the first 140 and second 142 ends is determined based on characteristics of the components located within the outer shell 124.

[0049] In the example shown in Figures 7-10, the sizing process utilizes a sizing tool 150 having a base 152 associated with a controller/actuator 154. A plurality of circumferentially spaced first fingers 156 extend axially outwardly from the base 152. At least one of the fingers 156a has a protruding portion 160 that is longer than a distal end of the remaining fingers 156. The protruding portion 160 can be formed to have varying profiles. In the preferred configuration, only one extended finger 156a has a protruding portion 160. This extended finger 156a is aligned to extend over and at least partially cover the sensor hole 146 during the sizing process for the first end 140. This provides a surface around the hole 146 that is sized to the first diameter Dl. During the sizing process, the actuator 154 moves the fingers 156 radially inwardly toward the center axis A to apply a compressive force F to reduce the outer shell 124 to the specified first diameter Dl. Operation and control of the sizing tool with a controller and actuator to reduce the outer shell to the desired size is well known and will not be discussed in further detail.

[0050] In this example, the apparatus includes a plurality of circumferentially spaced second fingers 170 that extend axially outwardly from the associated base 152 in a direction toward the first fingers 156. At least one of the fingers 170a has a recess portion 172 that receives the protruding portion 160 when the first 156 and second 170 fingers surround the outer shell 124. In the preferred configuration, only one finger 170a has a recess portion 172 to align with the protruding portion 160.

[0051] In this example, sizing the first end 140 and sizing the second end 142 occur simultaneously. Thus, there are two independent sizers/actuators 154 and both will size the outer shell 124 at the same time and speed. Whichever end has the larger diameter will stop first, and the other sizer will continue until the desired smaller diameter is achieved. In this configuration the deformation about the hole 146 is even further minimized as compared to the configurations shown in Figures 2-6.

[0052] As shown in Figure 10, the at least one extended finger 156a comprises a first finger body 180 extending to a first distal end 158 having a protruding tip 184. The at least one recessed finger 170a comprises a second finger body 190 that extends to a second distal end 192 having a recess 194 generally corresponding in shape to a shape of the protruding tip 184. The protruding tip 184 is received within the recess 194 during sizing of the first 140 and second ends 142.

[0053] In one example, the recess 194 comprises a curved indentation and the protruding tip 184 comprises a rounded portion that covers the sensor hole 146 and extends into the curved indentation when the first and second substrates are sized to the first and second diameters. Other shapes could also be used for the protruding and recess portions.

[0054] In the examples shown in Figures 2-10, the substrates have a circular cross-section. However, the substrates could also have other cross-section shapes. For example, the substrates could have an oval cross-section as indicated at 200 in Figure 11.

[0055] Further, in the examples shown in Figures 2-10 the outer shell includes one sensor opening or hole. Figure 12 shows an example where an outer shell 224 includes at least two openings 246. In this example, one of the first or second sets of fingers would include a second protruding tip with the other of the first and second sets of fingers including the corresponding recess portion. Additional openings 246 can be included as needed. For each hole in the outer shell there would be a corresponding protruding and recessed finger pair.

[0056] Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.