Patent Application
20080053646
The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings:
The present invention allows the tubes of an exhaust gas cooler to expand and contract without restraining them within the core bundle. This is achieved by the use of an intermediate seal or gasket between the header plate and the individual tubes. The seal prevents coolant from leaking out of the cooler and lets the tube length increase and decrease with the variation of the exhaust gas temperature. The seal is applied to the cold end of the core, where the temperatures are low enough on the tube wall to allow a polymer to be used without degradation over time. The geometry of the arrangement also encourages corrosive condensate to run away from the seal.
The cooler core is preferably brazed before assembly of the gasket seal onto the tubes. The gasket is preferably pushed over the tube ends and through the header. After assembling the gasket onto the tubes and header plate the tube ends are preferably expanded (flared) to resist the tendency of the pressurized coolant to force the gasket off the ends of the tubes. In a cooler with a secondary surface within the tubes the fin are preferably recessed within the tube to allow passage for the expansion punch.
Referring to the Figures, the exhaust gas cooler 10 of the invention comprises shell 12, tube bundle/core 14, and seal or gasket 16. The seal preferably comprises rubber, silicone, or polymer able to withstand the temperature ranges expected to be encountered by the particular exhaust gas cooler at issue. Inset 18 of
Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference.
