Patent Application
20080041042
Like reference symbols in the various drawings indicate like elements.
Referring now to
The catalytic converter members 14, 16 are here separate matrices, or bricks as they are sometimes called. By way of example, these bricks have the form of a ceramic honeycomb structure. Particles of a catalyst, usually platinum, are embedded in the surface of the matrix, the design of the matrix being intended to maximize the surface area over which the catalytic reaction takes place as, for example, described in U.S. Pat. No. 5,465,574 issued Nov. 14, 1995, inventor Ma, assigned to the same assignee as the present invention.
The annular structure 20 terminates at a front edge 34 and rear edge 32. The front edge 34 engages a rear, outer peripheral portion 33 of the frontal one of pair of catalytic converter members 12 and the rear edge 32 engages a frontal, outer peripheral portion 36 of the rearward one of the pair of catalytic converter members 16. Thus, the annular structure 20 has the front edge 34 disposed transverse to the longitudinal axis 18 and the rear edge 32 disposed traverse the longitudinal axis 18, such front edge 34 and rear edge 32 extending between the outer surface 40 and the inner surface 42 of the structure 20, the front edge 34 and rear edge 32 engaging outer peripheral portions of the catalytic converter members as described above. The annular structure 20 may be, for example, 300 series stainless steel, 400 series stainless steel, or any high temperature metal alloy with good oxidation and corrosion resistance characteristics. Here, the, for example, thickness of the annular structure is nominally 0.065 inches.
The housing 12 and annular structure 20 have apertures 50. 52 through them, such apertures being in registration with each other and being disposed along an axis 56 perpendicular to the longitudinal axis 18. An oxygen sensor 60 is disposed through the apertures 50, 52 and projects into the hollow region 22 of the annular structure 20 for measuring the amount of oxygen in the exhaust.
The catalytic converter 10 includes a one-piece thermally insulating support member 70 deposed between: an inner surface of the housing 12; and both the outer surface 40 of the annular structure 20 and outer surface portions of the pair of catalytic converter members 14, 16. The support member 70 has an aperture 72 in registration with apertures 52, 52 to enable the oxygen sensor 60 to pass through to region 22. This one-piece support member 70 or mat retains the catalytic converter members 14, 16 and the annular structure 20 in place and not allow the catalytic converter members 14, 16 to move inside the catalytic converter housing 12. Another purpose of this mat is to act as a thermal insulator between the catalytic converter members 14, 16 and the housing 12. Yet another purpose of this mat 70 is to improve NVH (Noise/Vibration/Harshness) characteristics of the catalytic converter 10. It is usually made of ceramic fibers, is flexible and pliable, and can be an expandable or non-expandable mat 70 depending on the formulation of the mat 70. This part provides thermal insulation. More particularly, the mat 70 wraps around the pair of catalytic members 14, 16 and the annular member 20 with outer taps 72 being inserted into opposing slots 76 of the one-piece member 70. To hold the mat 70 to the pair of catalytic members 14, 16 and the annular member 20, a piece of paper masking tape, not shown, is used to temporarily hold the mat 70 and the wrapped pair of catalytic members 14, 16 and the annular member 20 to form an assembly. The assembly is then slid into the housing 12. Heat generated by the gases harmlessly consumes the paper masking tape.
A pair of annular end caps 80, 82, here of a metal wire mesh material, may be disposed within the housing 12 at front and rear edges of the one-piece member 70 to protect its edges for erosion in certain applications. The assembly operation is as follows:
It is noted that by choosing the proper geometry and configuration of the middle section 20, other converter canning can be performed which are commonly known in the converter business as “Clam Shell” and “Shoe Box” converter designs.
A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. It should be noted that the geometry, especially the cross section contour of the center piece 20 can be changed to match with the cross section contour of the substrates 14, 16. This contour, in addition to being circular, can also be oval or a racetrack configuration (i.e., like an elongated oval), depending on the shape of the housing 12. Other embodiments include different types of materials for treating exhaust gases such as diesel particulate filters. Accordingly, other embodiments are within the scope of the following claims.
