A vehicle heat exchanger

Abstract: A vehicle heat exchanger (1), typically an oil cooler, has stacked galleries, including a first gallery system for containing a first fluid, and a second gallery system for containing a second fluid. The first and second gallery systems are sealed from one another and formed by a dimpled shell (2), a plain shell (4) nested within the dimpled shell element (2) and having a surface contacted by projecting dimples (15) of the dimpled shell (2)(to define a first gallery being); a turbulator (3) nested within the plain shell (4); and a further dimpled shell (2) nested in the plain shell (4), the further dimpled shell (a second gallery being defined between the further dimpled shell and the nesting plain shell, and occupied by the turbulator (4)).

Description: The present invention relates to a vehicle heat exchanger and in particular to a vehicle heat exchanger for use as an oil cooler in automotive applications. Oil coolers of brazed aluminium construction are known. These typically comprise a plurality of stacked brazable aluminium plates having interposed therebetween planar apertured turbulators. The turbulators space the plates defining fluid receiving galleries and provide a flow matrix for inducing agitated flow through the oil cooler. Typically the galleries are arranged in alternating fluid connection in the stack, a first connected gallery system defining a flowpath through the oil cooler for a cooling fluid (typically water); a second connected gallery system defining a flowpath through the oil cooler for the oil to be cooled. In such oil coolers the turbulators for the 'oil side' galleries and the 'water side' galleries are typically substantially identical (and of the same depth). The depth of the 'oil side' and 'water side' galleries is therefore substantially identical. It has been found that efficient oil cooler performance is achieved by reducing the 'water side' gallery depth and replacing the 'water side' turbulator by conical projections provided on relevant plates. 'Oil side' turbulators are necessary to provide the required surface area in view of the lower heat capacity of oil compared with water. The conical projections provide support preventing collapse of the 'water side' galleries when the oil cooler is pressurised. By reducing the depth of the 'water side' galleries the overall dimensions of the oil cooler can be minimised without significant compromise in performance. This is of substantial benefit in view of the premium placed on engine bay space in current vehicle engine design. The present invention seeks to provide an improved heat exchanger (particularly an oil cooler) of enhanced construction, durability and performance. Prior art heat exchangers are disclosed in, for example, EP-742418, DE-9309741 and EP-623798. The arrangement described in EP-623798 may be described as comprising a vehicle heat exchanger comprising a plurality of stacked galleries, including a first gallery system for containing a first fluid, and a second gallery system for containing a second fluid, the first and second gallery systems being substantially sealed from one another, the gallery systems being defined by a plurality of stacked elements comprising: i) a dimpled shell element including a tapered peripheral wall and a plurality of spaced dimples formed in and projecting away from a surface of the dimpled shell element; ii) a plain shell element nested within the dimpled shell element and having a surface contacted by the plurality of projecting dimples of the dimpled shell element, the plain shell element including a tapered peripheral wall nested in contact with the corresponding tapering peripheral wall of the dimpled shell element, such that the projecting dimples of the dimpled shell element abut the nesting plain shell element and define the nesting overlap of the peripheral tapered walls, a first gallery being defined between the plain shell element and the dimpled shell element; iii) a turbulator element nested within the plain shell element; and, iv) a further dimpled shell element being nested in the plain shell element, the further dimpled element including a tapered peripheral wall nesting in contact with the corresponding tapered peripheral wall of the plain shell element, and a plurality of spaced dimples projecting away from the turbulator element, a second gallery being defined between the further dimpled shell element and the nesting plain shell element, and occupied by the turbulator element. According to the present invention the dimples formed in the dimpled shell elements project upwardly in the same general direction as the tapered peripheral wall of the respective dimpled shell element. Desirably the elements comprising the heat exchanger are of brazable aluminium. Typically the plain shell element and/or the dimpled shell element and/or the turbulator are clad in a fusible brazing alloy when assembled, the fusible brazing alloy flowing during brazing to bond adjacent components at contact points. It is preferred that galleries in the first gallery system (the "water side" galleries) are of a depth less than galleries in the second gallery system (the "oil side" galleries). This leads to the space saving benefits identified above. The nested stacked sequence of dimpled shell, plain shell, turbulator element preferably repeats, typically to provide between 5 and 9 galleries in each gallery system. The peripheral wall of the plain shell element desirably extends beyond the peripheral wall of the dimpled shell element within which the plain shell element is nested. The peripheral walls of the nesting dimpled shell element the nested plain shell element and the further nested dimpled shell element beneficially define the outer wall of the heat exchanger. Tapering nesting peripheral walls for the dimpled and plain shell elements are particularly beneficial in accordance with the invention because good contact for brazing is ensured by the dimples of the dimpled shell element abutting (and defining the nesting overlap with) the plain shell element. The spaced dimples preferably taper from a root portion to a head portion, the head portion of a respective dimple desirably comprising a flat. The flat abuts against a respective portion of the plain shell element and provides improved contact surfaces for brazing. The turbulator element advantageously comprises a substantially planar element such as a turbulator plate, preferably including a plurality of apertures or formations permitting fluid flow through the turbulator element (and along the gallery). The turbulator element beneficially has an undulating profile including a series of undulations (preferably comprising spaced linear ridge lines) defining contact points with the adjacent dimpled shell element and shell element. The spaced elongate ridges of the turbulator are beneficially so spaced and arranged relative to the dimpled plate that contact with the dimpled shell is substantially with un-dimpled contact points. The plain shell element and dimpled shell element preferably have nested peripheral walls brazed together, as preferably have the plain shell element and further dimpled shell element. A fluid supply inlet and outlet is provided for the first gallery system, and a fluid supply inlet and outlet is provided for the second gallery system. Fluid communication means between successively stacked galleries in the same gallery system is provided. The fluid communication means comprises co-aligned apertures in the plain shell elements and dimpled shell elements, the co-aligned apertures having respective rims arranged either to seal against one another or be spaced from one another depending upon the fluid to be carried in a respective gallery. It is therefore preferred that both the dimpled and plain shell elements have respective co-aligned apertures having rims projecting toward the other of the respective dimpled or shell element. The fluid galleries are stacked alternately, such that adjacent galleries comprise galleries from alternate gallery systems. A heat exchanger according to the invention may be manufactured by building a stacked assembly of brazable aluminium elements comprising: v) a dimpled shell element including a plurality of spaced dimples formed in and projecting away from a surface of the first shell element; vi) a plain shell element nested within the dimpled shell element and having a surface contacted by the plurality of projecting dimples of the dimpled shell element, a first gallery being defined between the plain shell element and the dimpled shell element; vii) a turbulator element nested within the plain shell element; and, viii) a further dimpled shell element being nested in the plain shell element, the further dimpled element including a plurality of spaced dimples projecting away from the turbulator element, a second gallery being defined between the further dimpled shell element and the nesting plain shell element, and occupied by the turbulator element; and brazing the stacked assembly. The invention will now be further described in a specific embodiment, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 is a sectional view through a heat exchanger according to the invention; Figure 2 is a an exploded view of stacked elements comprising the heat exchanger of figure 1; and Figure 3 is a detailed sectional view of a dimpled projection provided on a dimpled shell. The oil cooler 1 is of brazed aluminium construction and comprises a series of nested stacked aluminium shells 2, 4 brazed to form the structure shown in Figure 1. The stacked shells 2, 4 define therebetween a "water side" gallery system communicating between a water inlet 5 and a water outlet (not shown in Figure 1) communicating through a top plate 6 of the oil cooler. A second gallery system is also defined by the shells 2, 4 comprising an "oil side" gallery system communicating between an oil inlet 7 and an oil outlet (not shown in Figure 1) communicating via base plate 8. As will be described in detail hereafter, the gallery system is arranged such that the stacked arrangement has "water side" galleries alternating with "oil side" galleries. Water flowing between the water inlet 5 and water outlet gains access to all water side galleries via apertures 9a, 10a, 9b, 10b provided in shell plates 2, 4 respectively. Upwardly extending rims 11, 12 provided for apertures 9b, 10b are sealingly brazed to the peripheral edge of respective apertures 9a, 10a to prevent ingress into the "oil side" gallery system (and vice versa). A vertical water "core" (having axis X) is shown in Figure 1 formed by stacked co-aligned apertures 10a,10b. Corresponding cores exist for the co-aligned apertures 9a, 9b and oil side apertures 16a, 16b and 17a, 17b. Dimpled shell 2 includes a spanning portion 13 terminating in an outwardly and upwardly inclined peripheral wall 14. Spanning portion 13 is provided with an array of dimpled projections 15, projecting upwardly in the corresponding direction to peripheral wall 14. On its obverse side spanning portion 13 is provided with a series of dimpled depressions (resulting from the deformation of plate 13 during the forming of the dimples 15). Apertures 16a, 17a in dimpled shell 2 and apertures 16b, 17b in plain shell 4 define the oil flow path through the oil cooler, permitting water to flow into the "oil side" galleries defined between the dimpled depressions on the underside of dimpled shell 2 and the planar uppermost surface 18 of plain shell 4. Upwardly extending rims 19, 20 around respective apertures 16a, 17a seal with corresponding aperture 16b, 17b (by brazing) provided on an adjacent upper stacked plain shell 4 (not shown in Figure 2) preventing leakage of the oil from the "oil side" gallery system. When assembled in a stack prior to brazing, the underside surface of a plain shell 4 sits on the dimpled projections 15 (of an underlaying dimpled shell 2). The dimples thereby space an upper plain shell 4 from an underlying, nesting dimpled shell 2. The outer peripheral wall 21 of plain shells 4 is inclined correspondingly to the outer peripheral wall 14 of dimpled shells 2 facilitating ease of nesting and ensuring that a plain shell 4 is snugly received in a respective underlying dimpled shell 2 such that the respective tapered walls 21, 14 are in face to face abutment with one another. This provides a good contact surface for brazing. Furthermore, in view of the fact that the respective peripheral walls 21, 14 are tapered, the tolerance required for nesting is relatively liberal. The dimpled projections 15 extend from a root portion 22 extending to a pinnacle in the form of a "flat" 23. The flat 23 provides a good contact surface for brazing with the underside of an above nesting plain shell 4. The water side galleries are defined between dimpled shells 2 and above nested shells 4 in the space across which dimples 15 project. Dimples 15 ensure good brazing contact between nested shells 4, 2 and also ensure that the water side galleries do not deform when the oil cooler is pressurised. The oil side galleries are defined between dimpled shells 2 and underlying plain shells 4, a turbulator plate 13 being present in the space between the upper surface 18 of plain element 4 and the dimpled depression underside of an overlying dimpled shell 2. The turbulator plate 13 may be of a form generally known in the art, and comprises a pressed aluminium component having a plurality of ridge formations extending generally transversely to the major axis of the turbulator plate, the ridges including a multiplicity of apertures permitting oil flow throughout the gallery. The upper surface of the turbulator plate 3 is brazed to the dimpled depression underside of overlaid dimpled shell 2. The underside of turbulator plate 3 is brazed to the planer surface of an underlaid plain shell 4. The turbulator plates 3 are nested in respective plain shells 2 during assembly. The side wall 21 extends upwardly beyond the top surface of turbulator plate 3 permitting the nesting of an overlaying dimpled shell 2 within the side wall 21. The dimensions of dimpled projections 15 and the depth of turbulator to plate 3 are arranged such that the "water side" galleries are of less depth than the "oil side" galleries. This is because it has been found that in view of the relatively higher heat capacity of water compared to oil, an "additional" turbulator (corresponding to the oil side turbulator 3) is not required in the water side gallery, the dimples 15 providing sufficient water agitation and surface area for good oil cooler performance to be achieved. The dimple projections 15 provide good brazing and sufficient structural integrity to avoid collapsing or bursting of the water galleries when the heat exchanger is pressurised with oil and water. The overall dimensions of the oil cooler can therefore be reduced compared to prior art arrangements. The nesting arrangement in which peripheral walls nest with dimpled shells 2 (and vice versa) provides an extremely convenient way of assembling a stacked oil cooler for brazing.

Claims: A vehicle heat exchanger (1) comprising a plurality of stacked galleries, including a first gallery system for containing a first fluid, and a second gallery system for containing a second fluid, the first and second gallery systems being substantially sealed from one another, the gallery systems being defined by a plurality of stacked elements comprising: i) a dimpled shell element (2) including an outwardly and upwardly inclined peripheral wall (14) and a plurality of spaced dimples (15) formed in and projecting away from a surface (13) of the dimpled shell element (2); ii) a plain shell element (4) nested within the dimpled shell element (2) and having a surface (18) contacted by the plurality of projecting dimples (15) of the dimpled shell element (2), the plain shell element (4) including a tapered peripheral, wall (21) nested in contact with the corresponding outwardly and upwardly inclined peripheral wall (14) of the dimpled shell element (2), such that the projecting dimples (15) of the dimpled shell element (2) abut the nesting plain shell element (4) and define the nesting overlap of the peripheral tapered walls (14, 21), a first gallery being defined between the plain shell element (4) and the dimpled shell element (2); iii) a turbulator element (3) nested within the plain shell element (4); and, iv) a further dimpled shell element (2) being nested in the plain shell element (4), the further dimpled element (2) including an outwardly and upwardly inclined peripheral wall (14) nesting in contact with the corresponding tapered peripheral wall (21) of the plain shell element (4), and a plurality of spaced dimples (15) projecting away from the turbulator element (3), a second gallery being defined between the further dimpled shell element (2) and the nesting plain shell element (4), and occupied by the turbulator element (3) ; characterised in that the dimples formed in the dimpled shell elements (2) project upwardly in the same general direction as the tapered peripheral wall (14) of the respective dimpled shell element (2). A vehicle heat exchanger (1) according to claim 1, wherein first galleries are of a depth less than second galleries. A vehicle heat exchanger (1) according to claim 1 or claim 2, wherein the peripheral wall (21) of the plain shell element (4) extends beyond the peripheral wall (14) of the dimpled shell element (2) within which the plain shell element (4) is nested. A vehicle heat exchanger (1) according to any preceding claim, wherein the spaced dimples (15) taper from a root portion (22) to a head portion (23), the head portion (23) of a respective dimple comprising a flat. A vehicle heat exchanger (1) according to any preceding claim, wherein the turbulator element (3) has an undulating profile including a series of undulations defining contact points with the adjacent dimpled shell element (2) and shell element (4), the undulations preferably comprising spaced elongate ridges, preferably wherein the spaced elongate ridges of the turbulator (3) are so spaced and arranged relative to the dimpled plate (2) that contact with the dimpled shell (3) is substantially with un-dimpled contact points. A vehicle heat exchanger (1) according to any preceding claim of brazed aluminium construction, wherein the plain shell element (4) and dimpled shell element (2) have nested peripheral walls (14, 21) brazed together, the dimples (15) of the dimpled shell elements (2) are brazed to respective adjacent plain shell elements (4). A vehicle heat exchanger (1) according to any preceding claim, wherein a first fluid supply inlet (5) and outlet is provided for the first gallery system, and a second fluid supply inlet (7) and outlet provided for the second gallery system, fluid communication means being provided between successively stacked galleries in respective gallery systems, the fluid communication means comprising co-aligned pairs of apertures (9a, 9b; 10a, 10b; 16a, 16b; 17a, 17b) in a plain shell element (4) and an adjacent dimpled shell element (2), a first co-aligned pair of apertures (9a, 9b; 10a, 10b) having respective rims formed to seal against one another, and a second co-aligned pair of apertures (16a, 16b; 17a, 17b) having rims formed to be spaced from one another. A vehicle heat exchanger (1) according to any preceding claim, wherein: i) the galleries are stacked alternately, such that a adjacent galleries comprise galleries from alternate gallery systems; and/or ii) the heat exchanger (1) comprises an oil cooler in which coolant (such as water) is supplied to the first gallery system and oil to be cooled supplied to the second gallery system.

Inventors: THOMAS GWYN, THOMAS, GWYN
Applicants: CALSONIC KANSEI UK LTD, CALSONIC KANSEI UK LIMITED
Application year: 2000
Main classification: F28D9
IPC codes: F28D9, F28F3