Multi-tube heat exchanger with mechanically interlocked tubes formed

Abstract

A multi tube heat exchanger core in which each tube is made from a pair of substantially identical thin sheet metal plates interfitted in a face to face relationship. Each plate has a pair of enlarged protuberances projecting side by side from the upper side surfaces thereof to form tank portions which are adapted to receive the heat exchanger fluid after the plates are built up into a core. The paired plates forming the tubes are mechanically and accurately aligned at their lower side ends by interfitting locking arms and arm receiving slots. To precisely space the tubes from one another so that air centers can be readily installed therebetween, the lower ends of the plates are formed with tube spacing flanges bent perpendicular to the plane of the plate that interlock with one another by tabs and notches. The tabs are formed with protrusions that extend the lower contact walls of the tabs downwardly to effectively increase tab width so that some portion of the tabs engage the corresponding contact wall of the associated notch to ensure contact between the tabs and their notches and thereby providing the predetermined spacing of the tubes from one another and their support to reduce crushing of the air centers during clamping and while being brazed in an oven. With this construction, allowance for normal dimensional variation in plate to plate stacking is provided. This construction also partially seals the lower end of the heat exchanger to optimize heat exchanger construction and efficiency.