In manufacturing heat exchangers of the tube and fin type where the tube ends project through a tube sheet or header plate, it is conventional to braze, solder, or weld the projecting ends of the tubes to the header plate. Such a sealing procedure is an expensive and time consuming operation. Another method of joining the tubes and header plate involves roll-expanding of the tubes or crimping operations. None of these methods are entirely satisfactory in providing a leak-proof joint.
More recently, resilient O-rings have been utilized with a tube rolling and crimping operation or potting compounds have been utilized to fill in the spaces between the tube ends and oversize openings in the header plates. However, these multi-operation sealing procedures are expensive and time consuming. The present invention obviates the disadvantages of these previously discussed methods of sealing.
The present invention comprehends the provision of a simplified method of sealing round tubes into a header-tank manifold or tube header. The method utilizes resilient grommets which are positioned over the ends of the tubes and are received in openings in the tube header. The exterior dimensions of the grommets are larger than the interior dimension of a header opening so that insertion of the grommet and tube into the tube header will compress the grommet around the exterior of the tube end.
The present invention also comprehends the provision of a method of sealing round tube ends into a header plate where the tube ends are initially rolled to provide an exterior bead or collar and the resilient grommets are fitted over the rolled tube end with the bead received in a groove in the grommet to retain the grommet in position when assembled into the header plate.
The present invention further comprehends a novel sealed connection between a core tube and a tube header plate mounted in a heat exchanger where the internal pressure will not be able to blow the grommet out of the header plate nor will the internal vacuum upon filling the system be able to suck the grommet into the tank.
Further objects are to provide a method and construction of maximum simplicity, efficiency, economy and ease of assembly, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.