CROSS REFERENCE TO RELATED APPLICATION(S)
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
Not applicable.
TECHNICAL FIELD
The present invention is directed toward heat exchangers, and particularly toward heat exchanger cores having flat tubes with ribs therebetween.
BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEMS POSED BY THE PRIOR ART
Heat exchangers are well known in the art. In the automotive and other fields, for example, heat exchangers typically include a core consisting of a plurality of tubes carrying a liquid or gas fluid with corrugated ribs disposed between the tubes. Collecting tanks are typically connected to the ends of the tubes to facilitate re-circulation of the fluid through the associated system (e.g., engine block) and then back through the heat exchanger tubes. The fins are heated by their contact with the fluid carrying tubes, and the cooling air takes away heat by cooling the fins.
Due to the advantages of minimized weight and size in many environments, particularly automobile engine compartments, a variety of structures have been proposed to provide efficient heat exchange in compact and lightweight heat exchangers. Among those proposals is the heat exchanger disclosed in U.S. Pat. No. 5,505,257, which is directed to heat exchangers which are tilted at an angle α from vertical 10 rather than normal to the flow of cooling air as is sometime necessitated by space constraints (as illustrated in FIG. 2 hereof). In that proposal, the ribs 12 are angled relative to the longitudinal orientation of the tubes 14 so as to account for the tilt and still define flow channels which are parallel to the direction of air flow into the core (whereby their inlets 16 and outlets 18 are aligned in the direction of air flow).
The present invention is directed toward overcoming one or more of the problems set forth above.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a heat exchanger core is provided with the front substantially vertical and facing cooling air flow. The core includes at least one row of flat tubes through which a liquid or gas flows, and corrugated ribs arranged in between the flat tubes. The ribs have wave flanks defining channels, each channel being for cooling air flow between an air inlet on the front of the core and an air outlet on the rear of the core. The wave flanks are at an angle β which is oblique to the core front and rear whereby the air inlet of each channel is offset relative to the corresponding air outlet.
In one form of this aspect of the present invention, the wave flanks are substantially planar with louvers in a significant section of the wave flanks protruding from the plane of the flank. In a further form of this aspect of the present invention, the louvers have an angle of bending defining protrusions in a common direction from the wave flank plane, with the angle of bending of each louver being substantially the same. In a still further form, the louvers have an angle of bending defining protrusions in opposite directions from the wave flank plane whereby half of the louvers are sloped in the direction of cooling air flow and the other half are sloped against the cooling air direction, the angle of bending of each louver being substantially the same. In yet another further form, a connector has edges bent at an angle corresponding to angle of bending of the louvers, with the connector being substantially in the center of the section of the wave flanks having louvers.
In a further form of this aspect of the present invention, the surface of the wave flanks is substantially flat.
In another form of this aspect of the present invention, the wave flanks have a curved contour between the air inlet and air outlet.
In another aspect of the present invention, a corrugated rib for a heat exchanger core is provided, where the corrugated rib is formed by rolling a longitudinally extending metal sheet and includes wave flanks defining cooling flow channels therebetween. The wave flanks have an oblique slope angle relative to the edges of the metal sheet and further include louvers protruding from the plane of the wave flanks.
In one form of this aspect of the present invention, the surfaces of the wave flanks are substantially flat.
In another form of this aspect of the present invention, the surfaces of the wave flanks are a contour consisting of a single arc.
In still another form of this aspect of the present invention, the louvers are fields of louvers arranged generally parallel and close to each other.
In still another aspect of the present invention, a heat exchanger core oriented with the front substantially vertical and facing cooling air flow is provided, the core including at least one row of flat tubes through which a liquid or gas flows and corrugated ribs arranged in between the flat tubes. The ribs have wave flanks defining channels, each channel being for cooling air flow between an air inlet on the front of the core and an air outlet on the rear of the core. The air inlet of each channel is aligned relative to the corresponding air outlet with the wave flanks between such inlets and outlets having a contour consisting of a single arc.
In one form of this aspect of the present invention, louvers protrude from the surface of the wave flank in a significant section of the wave flanks.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a portion of a heat exchanger incorporating the present invention;
FIG. 2 illustrates the previously described aspect of one prior art heat exchanger;
FIG. 3 is a perspective view of one embodiment of a corrugated rib according to the present invention;
FIG. 4 is a plan view illustrating the orientation of the wave flanks of a corrugated rib relative to the adjacent tube according to the present invention;
FIG. 5 is a perspective view of the corrugated rib and tube of FIG. 4;
FIG. 6 is a plan view illustrating the orientation of the wave flanks of a corrugated rib relative to the adjacent tube according to another embodiment of the present invention;
FIG. 7 is a perspective view of the corrugated rib and tube of FIG. 6;
FIG. 8 is a side view of a corrugated rib according to another aspect of the present invention;
FIGS. 9-12 illustrate alternate orientations of louvers in wave flanks along cross-sectional line A-A of FIG. 8;
FIG. 13 is similar to FIGS. 9-13, illustrating an orientation of louvers in contoured wave flanks;
FIGS. 14-16 are exemplary cross-sectional profiles of corrugated ribs which may be used according to the present invention;
FIGS. 17-18 illustrate one manner of producing corrugated ribs with flat wave flanks according to one aspect of the present invention;
FIG. 19 illustrates a corrugated rib formed according to FIGS. 17-18;
FIGS. 20-21 illustrate one manner of producing corrugated ribs with contoured wave flanks according to one aspect of the present invention;
FIG. 22 illustrates a corrugated rib formed according to FIGS. 20-21; and
FIG. 23 is a top view of a corrugated rib according to yet another aspect of the present invention, with contoured flanks and aligned inlets and outlets.
DETAILED DESCRIPTION OF THE INVENTION
A heat exchanger 30 according to the present invention is illustrated in FIG. 1. The heat exchanger 30 is set up perpendicular to the flow direction of the cooling air (arrow 32) as is prescribed in most applications in the automotive field or elsewhere, and includes a collecting tank 36 with an inlet or outlet connector 40 through which liquid or hot charge air flows in order to flow through a series of flat tubes 44 to the other collecting tank (not shown) lying on the opposite end of flat tube 44.
The gas or liquid flowing in the flat tubes 44 is cooled by cooling air flowing through corrugated ribs 46 firmly bonded to the flat tubes 44 (e.g., by soldering) to together form the heat exchanger grate or core such as is generally well known in the art.
In accordance with the present invention, the corrugated ribs 46 include wave flanks 50 which define channels 52 therebetween, with the channels 52 being laid out so that the corresponding air inlet 54 into each of the channels 52 is offset relative to the corresponding air outlet 56 from each of the channels 52. As illustrated in the embodiment of FIG. 1, in which the flat tubes 44 are vertically oriented, the air inlets 54 are higher than the level of the air outlets 56 for each channel 52. It should also be appreciated that other variants would be within the scope of the present invention. For example, the air outlets could lie higher than the associated air inlets or, in a heat exchanger having horizontally oriented tubes and ribs, the air outlets may lie to the right or left of the associated inlets (offset by 60 as indicated in FIGS. 4 and 6).
With an offset 60 between inlets 54 and outlets 56 such as shown in FIGS. 4 and 6, each air molecule, if possible, may advantageously come into contact with the wave flanks 50 of the corresponding channel 52 so that a higher efficiency of heat exchange is present. Inefficient horizontal flow through the channels 52 or flow without deflection, as generally can occur in the prior art, is avoided. It should also be appreciated that the size of the offset is influenced by the size of the angle between the wave direction and vertical or horizontal, as well as the depth of the heat exchanger grate. With a deeper heat exchanger grate at the same angle, the offset is larger than in a flatter heat exchanger grate.
Louvers 64 may also be advantageously provided in the wave flanks 50 for heat exchange efficiency whereby air turbulence may be improved without undesirably increasing the pressure loss of the cooling air stream. As illustrated in FIG. 3, the louvers 64 extend over a significant section of the wave flanks 50. The heat exchange rate between the liquid flowing in flat tubes 44 or, for example, a strongly heated charge air with the cooling air may thereby be significantly raised. The louvers may be variously configured as desired, depending upon the application.
Where louvers 64 are provided such as illustrated, it should be appreciated that the channels 52 will not be discrete, whereby an air particle entering a channel 52 through its inlet 54 may not emerge through the corresponding outlet 56. As a result, at least one part of the cooling air can be distributed to adjacent channels before it leaves the heat exchanger core again at the outlets.
The louvers may be advantageously configured to protrude from the plane of the wave flanks 50 running with the slope angle, with the heat exchanger core arranged with a slope to the direction of flow of the cooling air.
It should be appreciated that the depicted heat exchanger 10 may be designed with or without a tube bottom.
Since the corrugated ribs 46 in the depicted FIGS. 4-5 embodiment generally represent a parallelogram in top view, an angle a is produced between the ends of the flat tubes 44 running perpendicular to the vertical 66 and between the plane of the indicated tube bottom 68 (see FIG. 1) running perpendicular to vertical 66 and the corrugated rib 46. Should this angle a be perceived as a disadvantage, it can be avoided by appropriate choice of the position and contour of the separation cut during production of the corrugated ribs 46, which is done from a metal sheet.
FIGS. 4 and 5 show views of a flat tube 44 over its broad side with a corrugated rib 46 with obliquely running wave flanks 50 resulting in the indicated offset 60 between air inlets 54 and air outlets 56. The angle β1 between the wave direction 70 and the vertical 66 is indicated in FIG. 4, with vertical 66 coinciding with the trend of the edges of flat tube 44. The wave direction 70 is always the direction perpendicular to the wave flanks 50.
The angle β2 between the wave direction 70 and the horizontal 60 is present when a heat exchanger grate or core is arranged vertically with the flat tubes 44 extending horizontally (it being understood that the direction of flow of the cooling air is generally horizontal. In these cases as well, the cooling air stream naturally impinges on one of the narrow sides of flat tube 44 to then flow through the corrugated ribs 46.
FIGS. 6 and 7 differ from FIGS. 4 and 5 in that the wave flanks 50 of the ribs 46c are provided with a rounding or a contour 80.
FIG. 8 shows a perspective view of the corrugated rib 46 in which the trend of a cross-section A-A is indicated, and FIGS. 9-13 show different variants of louvers 64 in wave flanks 50 according to cross-section A-A. A connector 84 is provided between the louvers 64 arranged in two fields, the edges 85 of connector 84 being bent, with the angle of bending corresponding to the set angle 86 of the individual louvers 64. The louvers 64 can either be all aligned in one direction (e.g., FIGS. 11, 13) or in fields with opposite directions of alignment (e.g., FIGS. 9-10). As another alternative, FIG. 12 shows a variant in which the louvers 64 alternately protrude from the plane 88 of wave flanks 50.
FIG. 13 shows a variant with a contour 80 in the wave flanks 50 also provided with louvers 64, as well as an offset 60a between air inlet 54 and air outlet 56. Depending on the choice of contour 80, different alignment angles 86 can also be used with the alignment angle 86 being, for example, changed along the contour 80 to become larger or smaller. While louvers have been used in the art, to the knowledge of the applicant they have thus far not been suggested for use with a slope angle and/or with corrugations of the corrugated rib running with a contour.
FIGS. 14-16 illustrate alternate cross-sectional profiles of corrugated ribs 46 which may be produced by rolling. Such profiles may include, for example, the provision of the edges 90 with a larger bending radius 92 than the other bending edge. This may simplify production by rolling, with loosening of the corrugated rib 46 from the roller die facilitated by such profile.
FIGS. 17-18 show production of corrugated ribs 46 with flat wave flanks 50 having a slope relative to the edges. Rolls 100, 101 are designed with a corresponding oblique toothing 103. In order to form the louvers 64, the roller elements 100, 101 consist of a corresponding number of disk-like parts 104 that are assembled into a roller body. Each disk-like part 104 on the upper roll 100 cooperates with a corresponding part 104 on the lower roll 101 in the fashion of a blade in order to produce louvers 64 and their alignment from the plane 88 of wave flanks 50 (e.g., FIG. 19). Thus, it should be appreciated that corrugated ribs 46 according to the present invention may be produced cost-effectively on a roller machine (commonly used for large series production) with relatively high advance speed. Such roller machines may include a roll pair in a so-called roll stand and have an appropriate drive unit.
FIGS. 20 and 21 also illustrate rolling, in this case forming corrugated ribs 46c with a contour 80 of the wave flanks 50 such as previously described. The contour of the oblique toothing 103a must naturally correspond to the contour on the wave flanks 50, and emergence of the finished corrugated ribs 46 from the roll pair must be provided with an angle β corresponding to the slope angle. In front of this oblique exit, a region of the corrugated rib 46 is pushed together (tightened) before being brought to the desired division length L (see FIG. 3) at an angle corresponding to the slope angle.
FIG. 23 shows a top view of a corrugated rib 46 with an arc-like contour 80a of wave flanks 50, as proposed in an independent alternative solution, with no offset 60 between the air inlets 54 and the air outlets 56. Louvers 64 (not shown) may also be provided in this version), and the particular shape of the contour 80a may be selected depending upon the particular technical considerations of the heat exchanger and expected environment. It should be appreciated that the corrugated rib 46 of this variant also offers many of the advantages of the invention including enhanced heat exchange between the media as a result of a lengthened path for the cooling air.
It should thus be appreciated that the present invention may offer improved efficiency of heat exchange for the common situation in which the heat exchanger core may be mounted perpendicular to the direction of air flow. According to one aspect of the invention, the channels of the corrugated ribs are formed by the corrugated flanks so that the corresponding air inlet into each of the channels is arranged offset relative to the corresponding air outlet from each of the channels. In vertical flat tubes with corrugated ribs according to the invention the air can no longer flow horizontally through the channels, as in the prior art, since it is diverted by the vertical offset. If, on the other hand, horizontal flat tubes with corrugated ribs in-between are chosen according to the invention, the horizontally-flowing cooling air is diverted according to the offset in the horizontal. In either case, each air particle is forced to intensive contact with the wave flanks. Further, increased heat exchange intensity is achieved as a result of a longer connection path between the corrugated rib and the broad sides of the flat tubes, causing more intense heat exchange because it runs obliquely to the longitudinal axis of the flat tube.
Still other aspects, objects, and advantages of the present invention can be obtained from a study of the specification, the drawings, and the appended claims. It should be understood, however, that the present invention could be used in alternate forms where less than all of the objects and advantages of the present invention and preferred embodiment as described above would be obtained.
Patent Application
20050199378
