Abstract:
An assembly of two heat exchangers is readily formed or disassembled using spring clips to hold the two heat exchangers in assembled relation. The arrangement is such that the spring clips do not exert undesirable tension or compressional forces against either of the cores of the heat exchangers, but rather, exert only torsional forces at the points of connection.

Description:
FIELD OF THE INVENTION 
     This invention relates to heat exchangers, and more particularly, to an assembly of two heat exchangers which is such that assembly of the heat exchangers to each other or the disassembly of the two connected heat exchangers is easily effected. 
     BACKGROUND OF THE INVENTION 
     Many applications involving heat exchangers require the assembly of two or more heat exchangers together such that a common heat exchange fluid passes through both heat exchangers serially. A common example is the heat exchanger system of a vehicle. In such systems, the heat exchange fluid common to plural heat exchangers that is customarily employed is air and heat exchanger components of many systems are located in the forward part of the vehicle frame to receive air which is either drawn or propelled through the heat exchanger by a fan or passes through the heat exchanger as a result of ram air effects. Not untypically, the heat exchangers may include radiators for cooling engine coolant, charge air coolers for cooling combustion compressed by a turbocharger or a super charger prior to being directed to the engine, condensers for air conditioning systems, etc. 
     These heat exchangers are assembled together in close proximity when installed in the vehicle because of space constraints in the engine compartment in which the heat exchangers are normally disposed. Further, the heat exchangers are located in close proximity to one another so as to allow for a minimal frontal area that in turn allows the designer of a vehicle to achieve a more aerodynamically slippery effect to promote fuel economy. 
     While these practices most certainly are beneficial, they are not without one undesirable side effect. Specifically, when one of the heat exchangers requires servicing, as for example, in repairing a leak or when the heat exchanger requires complete replacement, it is often difficult to achieve easy access to the affected heat exchanger to cause its removal for replacement or repair. 
     In an attempt to avoid this problem, German patent document 19857508A1 discloses a construction wherein lower struts of one heat exchanger are inserted into lower supports on another heat exchanger. The first heat exchanger is then pressed such that upper struts thereon snap into upper spring clasps. The spring clasp is a specially produced part, and thus expensive. It is mounted with a leg on a sleeve formed on the tank of the second heat exchanger such that the other leg exerts a vertical force on the upper and lower struts of the first heat exchanger and on the core of the first heat exchanger. Unfortunately, the core of the first heat exchanger, which typically consists of relatively thin-walled flat tubes and corrugated fins is placed under compression. Over time, this may lead to failures at various joints. 
     Other proposals in which spring clips are used as fastening elements in heat exchangers include DE-OS-2018459, EP0046566B1, DE-AS2557967, DE3814007C1, DE19857512A1 and DE19857494A1. Various disadvantages attend the use of these structures as well with the consequence that there remains a real need for a heat exchanger assembly held together by spring clips to permit ease of assembly and disassembly without the disadvantages of the prior art constructions. In particular, there remains a need for such an assembly wherein compressive forces on the core of one of the heat exchangers can be avoided without having a significant adverse affect on the desired goal to effect simple assembly and disassembly of the heat exchanger construction. 
     SUMMARY OF THE INVENTION 
     It is the principal object of the invention to provide a new and improved assembly of two heat exchangers wherein the two may be held in assembled relation by a removable spring clip without exerting undesirable forces on either of the heat exchangers. 
     An exemplary embodiment of the invention achieves the foregoing object in an assembly that includes a first heat exchanger having a core through which a coolant may pass and elongated, generally vertical, spaced tanks in fluid communication with the core. A second heat exchanger is provided with a core with elongated spaced tanks flanking the core. A support is disposed on each of the tanks of the first heat exchanger at a lower part thereof and a mount is disposed on each of the tanks of the first heat exchanger at an upper part thereof. Two spaced lower struts are located on the second heat exchanger and are received in respective ones of the supports. In addition, two spaced upper struts are located on the second heat exchanger aligned with respective ones of the mounts. A removable spring clip secures each of the upper struts to the mount with which it is aligned and imparts a torsional stress to the struts. 
     As a result of this construction, undesirable compressive or tensional stresses on one or the other of the heat exchangers is avoided while a tight assembly is maintained as a result of the torsional stress. 
     In a preferred embodiment, each of the upper mounts includes a pin directed toward the second heat exchanger and each upper strut includes a slot loosely receiving the pin on the associated upper mount. Each spring clip is a hairpin cotter key having one leg abutting the corresponding upper strut and another leg abutting the pin on the associated mount oppositely of the corresponding upper strut. 
     A preferred embodiment contemplates that the one leg of the hairpin cotter key is straight and the other leg includes a concave surface receiving the pin. The pin, at its point of abutment with the other leg of the hairpin cotter key has a convex surface received within the concave surface on the cotter key. 
     A preferred embodiment contemplates that the supports be J-shaped having a short leg and a long leg opening upwardly. The long leg, at a location remote from the short leg, has a protrusion extending toward the short leg and engaging the associated lower strut. 
     Preferably, the tanks, the mounts, the struts and the supports are formed of aluminum. 
     A highly preferred embodiment contemplates that the struts are brazed to the second heat exchanger tanks and that the mounts and the supports are cast in the first heat exchanger tanks. 
     Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary, perspective view of a heat exchanger assembly made according to the invention; 
     FIG. 2 is an enlarged, fragmentary elevation of a lower support construction employed in an embodiment of the invention; and 
     FIG. 3 is an enlarged, fragmentary, elevation of an upper mount and spring clip assembly employed in the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While the invention will be described in connection with the assembly of two specific heat exchangers, namely, a charge air cooler and a condenser, the invention is applicable to the assembly of other types of heat exchangers to one another. For example, the assembly could include a radiator and/or an oil cooler connected to each other or to a condenser or a charge air cooler. Thus, no limitation to an assembly of a condenser and a charge air cooler is intended except insofar as expressly stated in the appended claims. 
     With the foregoing in mind, and with reference to FIG. 1, the assembly includes a charge air cooler, generally designated  10 , to which a condenser, generally designated  12 , is assembled. The charge air cooler includes a pair of spaced tanks  14  (only one of which is shown) which are fitted to header plates (not shown) on opposite sides of a core  16 . In the usual case, the tanks  14  are elongated and will extend vertically and the core  16  will be composed of a plurality of tubes in spaced relation provided with plate or serpentine fins extending between the tubes. The interior of the tubes will be in fluid communication with the tanks  14 . 
     Typically, each tank  14  will be formed by casting and will be cast of aluminum. Each tank  14  may include upper and lower mounting eyes  18 ,  20 , respectively by which the assembly may be secured to the frame or other parts of a vehicle, usually at the front end of the engine compartment thereof. 
     The condenser  12  includes a core  22  extending between tubular headers  24  (only one of which is shown). Flattened tubes having a relatively small hydraulic diameter extend between the headers  24  and are in fluid communication therewith. Serpentine fins, or in some instances plate fins, will be employed on the tubes in a customary fashion. Refrigerant inlet and outlet connections (not shown) will be associated with one or the other or both of the headers  24 . Again, the components of the condenser  12  will typically be formed of aluminum although other materials may be used if desired. 
     The tanks  14 , near their upper ends, include integrally formed mounts  26  (only one of which is shown). The mounts  26  will be described in greater detail hereinafter. 
     Near the lower ends of each of the tanks  14 , supports  28  are integrally formed as well. That is to say, the mounts  26  and the supports  28  will be integrally cast into the tank  14  as it is being formed. 
     The condenser  12 , near its lower end, includes outwardly directed struts  30  (only one of which is shown) and which are operatively received in a corresponding one of the supports  28  on a corresponding one of the tanks  14  of the charge air cooler  10 . Similarly, upper struts  32  (only one of which is shown) extend from the core of the condenser  12  for connection to the mounts  26  on the tanks  14  of the charge air cooler  10 . In the usual case, the struts  30  and  32  will be provided with saddle mounts of a conventional form and brazed to a corresponding one of the headers  24  of the condenser  12  as is well known. 
     The upper struts  32  each include a slot  34  which loosely receives a pin  36  formed on the corresponding mount  26  for purposes to be seen. A conventional hair pin cotter key  38  serves as a spring clip for securing the struts  32  to the corresponding one of the mounts  26 . 
     Turning now to FIG. 2, each support  28  is generally J-shaped having a long leg  40  and a short leg  42  which together define an upwardly opening slot  44 . Near its upper end, the long leg  40  includes a protuberance  46  that extends toward the short leg  44 , that is, in the direction of the strut  30 . This protuberance is, as is evident from FIG. 2, located on the long leg  40  at a location remote from the short leg  42 . As a consequence of this construction, when assembling the condenser  12  to the charge air cooler  10 , the lower struts  30  may be introduced into the slots  44  with the core  22  at a slight angle to the vertical. The upper end of the core  22  is then moved in the direction of an arrow  48  to a position approximately parallel to the core  16  of the charge air cooler. Thus, a lower side  50  of each lower strut  30  is engaged with the short leg  44  while an upper side  52  is engaged with the protuberance  46 . The opening  44  and the protuberance  46  are constructed so that the aforementioned engagement occurs just before the core  22  reaches parallelism with the core  16 . As a result, when the core  22  is urged just slightly closer to parallel, a torsional force will be imparted to the struts  30 . It is important to note that this force is applied to the struts  30  and not to the core  22  of the condenser  12 . In all events, the struts  30  are tightly held within the mount  28  as a result. 
     Turning now to FIG. 3, the structural arrangement of the components assembling the upper strut  32  to the mounts  26  is illustrated in greater detail. The pin  36  is seen to pass through the slot  34 . The pin  36  is integrally formed on the mount  26  and has an enlarged side  50  adjacent to header  14  and a projecting side  52  which enters the slot  34  and which is directed away from the tank  14 . The enlarged side  50  thus serves as a backing against which the upper struts  32  abut. Moreover, the enlarged side  52  includes, on its surface facing the tank  14 , a convex or curved surface  54 . 
     The hair pin cotter key  38  includes a straight leg  56  connected at one end by a loop  58  to a corrugated or serpentine leg  60 . The leg  60  includes a curved section  62  having a surface  64  facing the pin  36  that is concave and shaped to conform to the convex surface  54 . In addition, the end of the leg  60  terminates at end  66  that extends away from the straight leg  56 . The end  66  allows the legs  56  and  60  to be cammed apart when the hair pin cotter key  38  is being installed. 
     It will be recalled from the description of FIG. 2 that the upper end of the core  22  is pivoted toward the core  16 , and this is done when the upper struts  32  and the slot  34  therein are aligned with the projections  58  of the pins  36 . The pivoting action takes place until the upper struts  32  abut the enlarged part  50  of the pin  36  with the projections  52  entering the slots  34 . At this time, the cotter key  38  may be slipped over the assembly with the straight leg abutting the corresponding upper strut  32  and with the serpentine leg fitted about the enlarged part of the pin  50  such that its concave surface  64  receives the convex surface  54  of the pin  50 . 
     In this position, the desired torsional force in the struts is realized without the impartation of any compression or tension forces in either of the heat exchangers. The cotter key provides resilience to the connection so that the torsional forces cannot exceed those applied to the assembly by the interaction or squeezing action of the legs  56 ,  60 . The loose fit of the projection  52  in the slot  34  allows thermal expansion and contraction without inducing stresses in the assembly and the forces involved are sufficient to assure a tight connection of the two heat exchangers together without fear of rattling or the like. Disassembly is readily achieved simply by removing the cotter keys  38  by grasping the loops  58  and exerting an upward removing force, thereby removing the cotter keys  38 . A slight tipping of the core  22  away from the charge air cooler  14  to relieve the torsional force on the lower struts  30  is all that is required to free the condenser  12  from the assembly, allowing it to be removed simply by pulling upwardly on it after refrigerant line connections have been removed. 
     Thus, the invention achieves its object of providing a readily assembled and disassembled assembly of two heat exchangers through the use of spring clips without causing undesirable tension or compression forces to be exerted against the cores.