HEAT EXCHANGER

Abstract: A heat exchanger for use as an oil cooler consists of flat tubes (12) spaced apart in an array, with manifolds (16, 18) at opposite ends thereof, communicating with the interiors of the tubes and maintaining the tubes in the above-mentioned array.

Description: HEAT EXCHANGER This invention related to heat exchangers. It is particularly though not exclusively concerned with a heat exchanger and a method of manufacturing a heat exchanger. The present invention provides a heat exchanger comprising a stack of tubes maintained in a co-extensive spaced apart array, two manifolds communicating with the interiors of the tubes and maintaining the tubes in a spaced apart array at their ends. The manifolds can include through passages corresponding in number and size to the number and sizes of the tubes of the heat exchanger and end plates can close off the ends of the openings in the manifolds. The end plates can be provided with projections which correspond in number and size to the number and size of the openings in each of the manifolds. The heat exchanger can have one or more separators located on the heat exchanger between the two manifolds, and the or each separator can include through openings corresponding in number and size to the number and sizes of the tubes of the heat exchanger. The heat exchanger can have secondary heat exchange surfaces located between adjacent tubes and the secondary heat exchange surfaces can be in the form of a louvre or corrugation. The heat exchanger can have coolant deflectors arranged to direct cooling flow over the heat exchange surfaces of the heat exchanger, and the coolant deflectors can comprise angled plates attached to the top and bottom tubesof the tube array. Turbulators can be provided along the length of each tube to improve heat transfer; they may in addition provide resistance to crushing of the tubes. Such turbulators may be, for example, in the form of corrugated inserts or expanded metal inserts. The invention also provides a method of fabricating a heat exchanger comprising the steps of assembling the stack and manifolds in a jig, removing the assembly from the jig and undertaking a single brazing operation to unite the assembly. The present invention will now be particularly described with reference to the accompanying drawing which illustrates a partially assembled exploded view of one form of heat exchanger according to the present invention. Referring to the drawing a heat exchanger 10 comprises a spaced array 12 of flat walled tubes 14. Two manifolds 16 and 18 are provided one at each end of the array 12 and the manifolds maintain the tubes 14 of the array 12 in a spaced apart relationship at their ends. Each manifold has a number of through openings 16a, 18a respectively, the number and size of which correspond to the number and size of the tubes 14. End plates 20 and 22 close off the open ends of the through openings 16a and 18a respectively. Each end plate has dimples or semi-sheared locations 20a and 22a respectively which correspond to the number and size of the through openings 16a and 18a respectively. Each manifold 16, 18 is preferably formed from extruded aluminium and is drilled and/or tapped at 16b and 18b respectively for a fluid connection. Spacers to maintain the tubes 14 in the correct spaced apart relationship are disposed between the manifolds 16 and 18 and can be in the form of a spacer 24 or a spacer 26, or a combination of both spacers. Both spacers are extruded aluminium and the spacer 24 is similar in nature to the manifolds in that it is provided with through openings which correspond in number and size to the through openings in the manifolds. The spacer 26 comprises a number of parallel arms 26a, the number and size defining adjacent openings corresponding in number and size to the number and size of the tubes 14. A secondary heat exchange surface 28 is provided between adjacent tubes 14 and the secondary heat surface can be in the form of corrugations as shown, or louvres. The heat exchanger 10 is provided with coolant deflectors 30 which are attached to the top and bottom ones of the tubes in the tube array 12 and serve to direct the coolant flow onto the heat exchange surfaces of the heat exchanger. The interior of each tube 14 in the tube array is provided with turbulators 32 to cause turbulence in the fluid flow along the tubes in order to improve heat transfer and to provide resistance to any crushing of each of the flat tubes. The heat exchanger 10 is assembled by locating the spacers 24, 26 so that the tubes pass through openings in the spacers, the interior of each of the tubes 14 having already been fitted with the turbulators 32. The ends of the tubes are then inserted partially into the through openings of the respective ones of the manifolds 16 and 18 and the end plates 20 and 22 are attached to the respective ones or the manifolds since the depressions or locations on the end plates retain the end plates on the respective manifold. The secondary heat exchange surfaces 28 are then located between adjacent tubes and the heat exchanger thus assembled can then be passed to a brazing apparatus. The components of the oil cooler are of aluminium and the end plates are of clad aluminium which means that the cladding of lower melting aluminium melts during the brazing operation. The brazing operation may be carried out in an inert gas. The coolant deflectors 30 can be attached to the heat exchanger subsequently to brazing, or they can be attached prior to brazing and thus be brazed as a complete heat exchange assembly provided that the coolant deflectors are retained in position prior to brazing by the separators. The oil cooler is particularly suited because of its shape to being water cooled by insertion in a header tank of a radiator. The oil cooler is equally well suited to being air cooled and for this purpose the secondary heat exchange surfaces 28 are particularly provided.

Claims: CLAIMS. 1. A heat exchanger comprising a stack of tubes maintained in a co-extensive spaced apart array, by means of spaced manifolds each communicating with the interiors of the tubes. 2. A heat exchanger according to claim 1, wherein the manifolds include through passages corresponding in number and size to the number and sizes of said tubes. 3. A heat exchanger according to claim 2, which exchanger contains end plates to close off the ends of said passages. 4. A heat exchanger according to claim 3, wherein said end plates are provided with projections which correspond in number and size to the number and size of the passsages in each of the manifolds. 5. A heat exchanger according to any of claims 1 to 4, which comprises one or more separators provided on the heat exchanger between the two manifolds. 6. A heat exchanger according to claim 5, wherein the separator includes through openings corresponding in number and size to the number and sizes of the tubes of the heat exchanger. 7. A heat exchanger according to any of claims 1 to 6, which comprises secondary heat surfaces located between adjacent ones of said tubes. 8. A heat exchanger according to claim 7, wherein the secondary heat exchange surfaces are louvred or corrugated form. 9. A heat exchanger according to any of claims 1 to 8, which has coolant deflectors arranged to direct coolant flow over the heat exchange surfaces of said heat exchanger. 10. A heat exchanger according to claim 9, wherein the coolant deflectors comprise angled plates attached to respective spaced end tubes of said array. 11. A heat exchanger according to any of claims 1 to 10, wherein turbulators are provided along the length of each tube. 12. A heat exchanger according to claim 11, wherein said turbulators are in the form of corrugated inserts or expanded metal inserts. 13. A method of fabricating a heat exchanger according to any of claims 1 to 12, which comprises the steps of assembling a stack of heat exchange tubes in a co-extensive spaced apart array wih a pair of manifolds in a jig, removing the assembly from the jig and carrying out a single brazing operation to unite the assembly.

Inventors: HOWELLS DAVID RAYMOND, HOWELLS, DAVID, RAYMOND
Applicants: LLANELLI RADIATORS LTD, LLANELLI RADIATORS LIMITED
Application year: 1990
Main classification: F28D1
IPC codes: F28D1, F28F9