TANK HEADER PLATE CONNECTION

Abstract: A connection for securing a tank (10) to a header plate (12) in a heat exchanger. A metal header plate (12) is provided with a peripheral groove (28) having a bottom wall (32) and an upstanding side wall (30). A compressible gasket (40) is received in the groove (28) to compress the gasket (40). A plurality of tabs (42) are deformed from the side wall (30) to overlie a side (22) of the flange (20) of the tank (10). The tabs (42) are generally egg-shaped or spherical and have free edges (44) engaging the flange (20) to provide excellent resistance to deformation.

Description: This invention relates to heat exchangers of the type having a header plate supporting the open ends of a plurality of tubes and a tank secured to the header plate. The efforts by the automotive industry to reduce the weight of vehicles have brought about an increasing use of non-metallic materials in various parts of vehicles. Heat exchangers, more commonly termed radiators, are no exception. While metal materials are still employed in the cores for such heat exchangers because of their greater thermal conductivity over plastics, other heat exchanger components that do not require good thermal conductivity are being made of plastic. A primary example is the so-called tank which is fitted to the heat exchanger core, typically by securement to the header plates which define the ends of such cores. Because the joint between the header plate and the tank is one of dissimilar materials, prior techniques of brazing or soldering the joint can no longer be employed. In lieu thereof, to effect the necessary seal, a gasket is disposed between the tank and the header plate and any of a variety of means are employed to hold the components in assembled relation with the gasket under compression to assure a seal at the operating pressures for which the heat exchanger was designed. It is, of course, necessary that the means employed to effect the connection be strong and long lived to prevent leakage. At the same time, it is desirable that the means be such that disassembly of the component parts can be effected when required for servicing. It is also desirable that the means utilized lend themselves to use in mass production to minimize cost. Attempts to achieve these objects have resulted in proposals wherein a header plate is provided with a peripheral groove in which the gasket to be compressed may be disposed. The tank is provided with a peripheral flange sized to be received in the groove and adapted to compress the gasket therein. The outer wall of the groove is then deformed in part to overlie the flange on the tank and hold the same in a position compressing the gasket. This approach is exemplified by US-A-4 331 201 which discloses the features according to the precharacterising part of claim 1. Unfortunately, because this approach involves deformation of a metal wall which necessarily may be sufficiently thin as to be easily deformed, the same may not always be as strong as might be desired. Pressure within the system during operation will act against the deformed material and tend to deform it back toward its original configuration. When such occurs, the compressive forces exerted on the gasket are lessened and leakage may occur. According to the present invention there is provided a heat exchanger comprising : a metal header plate supporting the open ends of a plurality of tubes ; a gasket receiving area extending about the periphery of said header plate and having a bottom wall surrounded by an upstanding deformable side wall terminating in an edge ; a compressible gasket in said gasket receiving area ; a plastics tank having an opening surrounded by an outwardly extending flange, said flange being sized and configured to be fitted within said gasket receiving area with one side of the flange abutting said gasket and another side of the flange within said area and spaced from said side wall edge, said tank compressing said gasket so that said gasket effects a seal between said tank and said header plate ; and a plurality of tabs in said side wall overlying said another side to hold said tank in compressing relation to said gasket, each said tab being formed by deformation and piercing of said side wall after said flange has been fitted within said gasket receiving area to have a nominally planar, free edge displaced from said side wall and in contact with said another side of said flange, characterised in that each said tab is located below the side wall edge and tapers from said free edge toward said side wall edge to merge into said side wall on all sides of said tab except that defining the free edge prior to or at said side wall edge and that said side wall in the area of said tabs and above said free edge is deformed towards said tank to at least overlie said flange to assure abutment of said free edges with said another side. The chosen configuration of the tabs provides excellent force distribution to the side wall of the gasket receiving area or groove so as to provide excellent resistance to deformation back toward the original shape. At the same time, the tabs are easily formed according to mass production techniques and, where necessary, may be intentionally deformed back to their original configuration to allow disassembly of the components. Preferably, each tab is generally part eggshaped, or part spherical. The tabs may be formed in the side wall by punching or piercing. No restraint is placed on the portion of the side wall wherein the tabs are formed such that such portion may be slightly bent toward the tank. Thereafter the side wall is rolled or bent from the vertical to partially overlie the flange such that the free edges of the tabs are parallel to the upper surface of the flange. The invention will be better understood from the following description or a preferred embodiment thereof, given by way of example only reference being had to the accompanying drawings, wherein : Fig. 1 is a perspective view of a tank assembled to a header plate by a connection made according to the invention ; Fig. 2 is a fragmentary, enlarged elevation of the assembly ; Fig. 3 is a further enlarged, sectional view taken approximately along the line 3-3 in Fig. 2 ; and Fig. 4 is a fragmentary enlarged view of the header plate with a tab formed therein but with the tank removed for clarity. Description of the Preferred Embodiment An exemplary embodiment of the invention is illustrated in the drawing and with reference to Figs. 1 and 3 thereof, is seen to include a radiator tank 10, typically formed of plastic, and a header plate 12 formed of metal. Conventionally, the header plate 12 receives the open ends 14 of a plurality of tubes 16 (only one of which is shown). The tank 10 has an opening 18 which is surrounded by an outwardly directed flange 20 having upper and lower sides 22 and 24, respectively. One or more coolant ports 26 are provided for the tank 10. As best seen in Fig. 3, the header plate 12, at its periphery, includes a groove, generally designated 28. The groove 28 is defined by an upstanding, outer side wall 30, a bottom wall 32 and an inner wall 34 generally parallel to the outer wall 30 which merges with the main body of the header plate 12 by means of a round 36. As can be seen, the groove 28 and flange 20 are sized and configured so that the latter may be received in the former. A compressible gasket 40 is disposed in the groove 28 in abutment with the bottom wall 32 thereof and the tank 10 oriented so that the flange 20 may be introduced into the groove 28. Upon introduction of the flange 20 into the groove, the surface 24 is brought into abutment with the gasket 40 and continued urging of the tank 10 toward the header plate 12 will result in the gasket 40 being compressed to the desired degree. In the usual case, somewhat more than the desired compression force will be placed on the components to allow a series of tabs 42 to be deformed from the wall 30 to overlie the surface 22 of the flange 20. When the tabs 42 have been formed, the compressive force may be released and the structure will assume the configuration illustrated in Fig. 3. To assure good retentive strength and a resistance to deformation in response to pressure within the tank 10, the tabs 42 have the shape of one quadrant of a sphere or an egg. They include a curved lower free edge 44 which is nominally planar and overlies and abuts the surface 22 of the flange 20. The tabs 42 gradually taper from their edges 44 toward the outer side wall 30 to line 46. Generally, the edge 48 of the sidewall 30 is reached such that a space 50 exists between the edge 48 and the tab 42. The tabs may be formed in one single operation with an appropriate shaped tool which effectively pierces the outer wall 30 to define a free edge 44 while deforming a portion of the wall 30 to define the body of the tab 42. This forming process is readily adaptable to mass production techniques. To simplify the assembly operation, and to minimize the tooling required, the upper portion 52 of the side wall 30 wherein the tabs 42 are formed is not restrained oppositely of the advancing punching or piercing tool during the punching or piercing operation. This in turn may result in the upper portion 52 of the side wall 30 being slightly bent toward the tank 10. Because the tabs 42 are formed by deforming metal, metal flow during the forming operation may result in the free edges 44 of the tabs being increasingly spaced from the upper surface of the flange 20 in the direction away from the side wall 30 and toward the tank 10. Consequently, to bring the entire extent of each free edge 44 into contact with the upper surface of the flange 20, following the operation wherein the tabs 42 are formed. The invention contemplates that the upper portion 52 of the side wall may be further bent along a line 54 approximately at the level of the free edges 44 in the direction of the tank 10. As a consequence, the upper portion 52 of the side wall 30 will remain upstanding but will partially overlie the flange 20 and the free edges 44 will be parallel to and abut the upper surface of the flange 50. The bending operation can be performed by any suitable process as, for example, by rolling. In a preferred embodiment, the upper portion 52 is bent approximately 30° from the vertical toward the tank 10. It will be appreciated that when necessary, the tabs 42 may be deformed back to their original shape if, for any reason, it is necessary to remove the tank 10 from the remainder of the assembly. In this regard, it is desirable that the tabs 42 or the upper portion 54 of the side wall 30 do not extend inwardly to be in contact with a side wall 56 of the tank 10 so as to allow insertion of a tool to accomplish such deformation. Finally, it will be appreciated that the geometry of the tabs 42 assures that forces tending to separate the tank 10 from the header plate 12 will be evenly distributed to the outer wall 30 to resist deformation of the same that could result in release of compressive force on the gasket 40 that could in turn result in leaks. The free edges 44 provide a substantial zone of contact with the flange surface 22 and such forces as are placed against the edges 44 are distributed to the remainder of the respective tab 42 which will be placed in compression without an appreciable bending moment applied thereto. Consequently, an extremely reliable and easily formed connection is provided by the invention.

Claims: A heat exchanger comprising: a metal header plate (12) supporting the open ends of a plurality of tubes (16); a gasket receiving area (28) extending about the periphery of said header plate and having a bottom wall (32) surrounded by an upstanding deformable side wall (30) terminating in an edge (48); a compressible gasket (40) in said gasket receiving area; a plastics tank (10) having an opening surrounded by an outwardly extending flange (20), said flange being sized and configured to be fitted within said gasket receiving area with one side (24) of the flange abutting said gasket and another side (22) of the flange within said area and spaced from said side wall edge (48), said tank compressing said gasket so that said gasket effects a seal between said tank and said header plate; and a plurality of tabs (42) in said side wall overlying said another side (22) to hold said tank in compressing relation to said gasket, each said tab being formed by deformation and piercing of said side wall after said flange has been fitted within said gasket receiving area to have a nominally planar free edge (44) displaced from said side wall and in contact with said another side (22) of said flange, characterised in that each said tab (42) is located below the side wall edge (48) and tapers from said free edge (44) toward said side wall edge (48) to merge into said side wall (30) on all sides of said tab except that defining the free edge prior to or at said side wall edge (48), and said side wall (30) in the area of said tabs (42) and above said free edge (44) is deformed towards said tank (10) to at least overlie said flange (20) to assure abutment of said free edges (44) with said another side (22). A heat exchanger according to claim 1 characterised in that each said tab (42) is generally part egg-shaped or part spherical. A heat exchanger according to claim 1 or claim 2 characterised in that said deformed side wall area is deformed approximately 30 degrees towards said tank (10).

Inventors: MUNCH, JOHN E., JR., STAY, KEVIN E., WEHRMAN, JAMES L.
Applicants: MODINE MANUFACTURING COMPANY
Application year: 1985
Main classification: F28F9
IPC codes: F28F9