Heat exchange – Flow passages for two confined fluids – Interdigitated plural first and plural second fluid passages
Reexamination Certificate
2000-12-28
2002-12-24
Leo, Leonard (Department: 3743)
Heat exchange
Flow passages for two confined fluids
Interdigitated plural first and plural second fluid passages
C165S916000, C123S1960AB
Reexamination Certificate
active
06497274
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to heat exchangers, including oil coolers of the so-called “doughnut” type that can be used separately or in conjunction with oil filters in automotive and other engine and transmission cooling applications and heat exchangers or oil coolers having a rectangular shape. This invention also relates to manifolds for the transfer and distribution of two fluids, particularly heat exchanging fluids.
Oil coolers have been made in the past out of a plurality of stacked plate pairs located in a housing or canister. The canister usually has inlet and outlet fittings for the flow of engine coolant into and out of the canister circulating around the plate pairs. The plate pairs themselves have inlet and outlet openings and these openings are usually aligned to form manifolds, so that the oil passes through all of the plate pairs simultaneously. These manifolds communicate with oil supply and return lines located externally of the canister. An example of such an oil cooler is shown in Japanese Utility Model Laid Open Publication No. 63-23579 published Feb. 16, 1988.
Where the oil cooler is used in conjunction with an oil filter, the plate pairs are usually in the form of an annulus and a conduit passes through the center of the annulus delivering oil to or from the filter located above or below the oil cooler and connected to the conduit. The oil can pass through the filter and then the oil cooler, or vice-versa. Examples of such oil coolers are shown in U.S. Pat. Nos. 4,967,835 issued to Thomas E. Lefeber and 5,406,910 issued to Charles M. Wallin.
A difficulty with these prior art heat exchangers (HXs) however is that they have limited performance efficiency. This limitation is exacerbated in applications where compact HX configurations are required. In particular, in prior art HXs at least one of the fluids must be circulated through the stack plate passages in a circumferential, or split-flow circumferential flow direction. This results in a high flow resistance, or pressure drop for this fluid. Also, the necessity to include relatively large fluid ports within prime regions of the plate area that could otherwise be used for heat transfer, detracts from overall performance or compactness. Thirdly, there are inherent flow distribution problems with one or all of the fluids being distributed around, or between the plate heat transfer passages, which are difficult to overcome in prior art designs. Finally, to maximize heat transfer efficiency it is desirable to achieve a true counter-flow direction between the two fluids, yet this is impractical in prior art constructions. In these cases, the two fluids flow at essentially perpendicular directions.
The present invention provides a high performance compact heat exchanger in which the two fluids can have a true parallel flow direction including counterflow direction and yet low pressure drop. Further the HXs described herein can achieve extremely uniform flow distribution according to the flow conditions required, and a graduation means to control this in changing section, or irregular shaped HXs. There is also provided a novel manifold that allows flexibility in locating external fluid connections, while providing a low pressure drop and balanced flow distribution interface with the HX internal fluid distribution manifolds.
The present invention is expected to have particular applicability to compact automotive heat exchangers, including oil/water transmission and engine oil heat exchangers and other high performance liquid to liquid or liquid to gas heat exchangers. The present invention offers particular benefits for refrigerant to water (or other liquid) HX's in as much as two phase fluids are normally particularly sensitive to flow maldistribution effects, both within the heat exchange passages and the connection manifolds, and which the present invention overcomes.
More specifically, a preferred embodiment of the present invention is a high performance, plate type compact HX based on structural provision of cross-over passages that intersect internal fluid distribution manifolds. These cross-over passages allow both fluids to be directed in a short path, counterflow relationship. A low pressure drop is simultaneously achieved for both fluids, based on the resultant short paths, and by judicious selection of appropriate heat transfer augmentation means.
In one preferred version of the invention, there is a deliberate adjustment of the size and shape of fluid transfer apertures that are arranged in groupings to allow parallel flow distribution, the adjustment being used to achieve uniform flow distribution across the plate surfaces, and over a range of HX shapes.
A preferred embodiment of the present invention is a heat exchanger having a self-enclosing configuration, ie without the need for an external housing to contain one of the fluids. If desired, the invention can still be used in a form having an external “can” or housing that contains the heat exchanger.
Optional design features of these HXs are also described that include a fluid passage to allow partial bypassing of one fluid, in the case that an excess flow supply needs to be accommodated, and internal cones to improve flow distribution.
The heat exchanger of the present invention is very efficient with relatively low pressure drop. In one version of the present heat exchanger employing mating ringlike plates which are placed in a stack, the two heat exchanging fluids are able to travel radially so the two fluid flows are parallel to one another. Thus, the first heat exchanging fluid can flow radially through inner flow passages formed between the plates while a second heat exchanging fluid is able to flow through outer flow passages formed between back-to-back plate pairs. In another version of the heat exchanger of the invention which can employ generally rectangular plates, again, the two heat exchanging fluids are able to flow in inner and outer flow passages in parallel directions.
In one version of the invention employing ringlike or annular plates and annular primary and secondary bosses, radially extending ribs are formed about the circumference of one or more of the primary bosses and extend substantially across their respective boss. These ribs are located between and separated from openings formed in their respective primary bosses and they form cross-over passages that permit one of the heat exchange fluids to flow radially across the primary bosses and through inner flow passages. In a rectangular embodiment of the heat exchanger, each plate in the stack is formed with first and second elongate primary ridges and at least one secondary ridge and at least a portion of the primary ridges have ribs extending transversely across the width of the ridge and distributed along the length thereof. Again, these ribs are located between and separated from openings formed in the primary ridges and form cross-over passages that permit one of the heat exchanging fluids to flow transversely across the primary ridges and through inner flow passages.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a heat exchanger comprises an plurality of stack plate pairs consisting of face-to-face, mating ringlike plates, each plate having a peripheral flange and annular inner and outer primary bosses each having a portion thereof located in a common first plane with the peripheral flange. Each plate also has an annular secondary boss having a portion thereof located in a second plane spaced from the first plane and parallel thereto. Intermediate areas are located between the inner and outer primary bosses and the peripheral flanges and the primary bosses in the mating plates are joined together. The intermediate areas of each plate pair have spaced-apart portions to form an inner flow passage between the plates. The secondary boss is located adjacent to one of the primary bosses and on a side thereof furthest from the other of the primary bosses. Both the primary bosses and the secondary bosses have openings formed the
Dykema Gossett PLLC
Leo Leonard
Long Manufacturing Ltd.
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