Patent Application
20060081358
This invention relates to plate-type heat exchangers for effecting heat transfer between two fluids, for example between a lubricating oil and a liquid coolant.
Plate-type heat exchangers comprising a stack of heat exchanger plates are well known. Such heat exchangers are commonly employed for effecting heat transfer between a first fluid, for example a lubricating oil to be cooled, and a second fluid, for example a liquid coolant.
There is a need for improved heat exchangers of this type which are economical to manufacture and in which the heat transfer between the fluids is optimized.
In accordance with the present invention there is provided a heat exchanger comprising a plurality of first fluid core plates and a plurality of second fluid core plates, each of the core plates comprising a periphery; a first end; a second end; a generally flat base having a top surface and a bottom surface; a first fluid inlet opening proximate the first end of the plate; a first fluid outlet opening spaced from the first fluid inlet opening toward the second end of the plate; a second fluid inlet opening; and a second fluid outlet opening;
wherein the first fluid inlet and outlet openings are spaced from one another along a plate axis and wherein the second fluid inlet and outlet openings are located on opposite sides of the plate axis;
each of the first fluid core plates further comprises a first raised barrier portion having an upper surface which is raised relative to the top surface of the base and relative to the first fluid inlet and outlet openings, the first raised barrier portion having a first end proximate the first fluid inlet opening and a second end spaced from the first fluid inlet opening toward the second end of the plate, the second end of the first raised barrier portion being spaced toward the second end of the plate relative to the first fluid outlet opening, with a first fluid flow gap being provided between the second end of the first raised barrier portion and the second end of the plate through which the first fluid can flow between the first fluid inlet and outlet openings;
each of the first fluid core plates further comprises a first recessed barrier portion having a lower surface which is recessed relative to the bottom surface of the base, with both the first fluid inlet and outlet openings being formed in the first recessed barrier portion, the first recessed barrier portion having a first end proximate the first end of the plate and a second end proximate the second end of the plate, wherein a second fluid flow gap is provided through which the second fluid can flow between the second fluid inlet and outlet openings, the second fluid flow gap being spaced toward the first end of the plate relative to at least one of the second fluid inlet and outlet openings;
each of the second fluid core plates further comprises a second raised barrier portion having an upper surface which is raised relative to the top surface of the base, with both the first fluid inlet and outlet openings of the second plate being formed in the second raised barrier portion, the second raised barrier portion having a first end proximate the first end of the plate and a second end proximate the second end of the plate, wherein a second fluid flow gap is provided through which the second fluid can flow between the second fluid inlet and outlet openings, the second fluid flow gap being spaced toward the first end of the plate relative to at least one of the second fluid inlet and outlet openings;
each of the second fluid core plates further comprises a second recessed barrier portion having a lower surface which is recessed relative to the bottom surface of the base and relative to the first fluid inlet and outlet openings, the second recessed barrier portion having a first end proximate the first fluid inlet opening and a second end spaced from the first fluid inlet opening toward the second end of the plate, the second end of the second recessed barrier portion being spaced toward the second end of the plate relative to the first fluid outlet opening, with a first fluid flow gap being provided between the second end of the second recessed barrier portion and the second end of the plate through which the first fluid can flow between the first fluid inlet and outlet openings;
the first fluid core plates and the second fluid core plates being in alternating stacked relationship with the periphery of each first fluid core plate being sealed to the periphery of an adjacent second fluid core plate to form a plurality of fluid flow passages;
said plurality of fluid flow passages comprising a plurality of first fluid flow passages for flow of the first fluid, each of the first fluid flow passages being formed between the top surface of a first fluid core plate and the bottom surface of an upwardly adjacent second fluid core plate, with the upper surface of the first raised barrier portion of the first fluid core plate being in sealed contact with the lower surface of the second recessed barrier portion of the second fluid core plate and with the gap of the first raised barrier portion communicating with the gap of the second recessed barrier portion, such that the first fluid can flow from the first fluid inlet opening, through the first fluid flow passage, and through the gaps to the first fluid outlet opening;
said plurality of fluid flow passages further comprising a plurality of second fluid flow passages for flow of the second fluid, each of the second fluid flow passages being formed between the top surface of a second fluid core plate and the bottom surface of an upwardly adjacent first fluid core plate, with the upper surface of the second raised barrier portion of the second fluid core plate being in sealed contact with the lower surface of the first recessed barrier portion of the first fluid core plate and with the gap of the second raised barrier portion communicating with the gap of the first recessed barrier portion, such that the second fluid can flow from the second fluid inlet opening, through the second fluid flow passage, and through the gaps to the second fluid outlet opening;
wherein the first fluid flow passages alternate with the second fluid flow passages.
It will be appreciated that alternatively the first fluid may flow in the reverse direction through the first fluid flow passage in which case the first fluid outlet openings in the plates would function as first fluid inlet openings, and the first fluid inlet openings in the plates would function as first fluid outlet openings.
In order that the invention may be more clearly understood and more readily carried into effect, the same will now, by way of example, be more fully described with reference to the accompanying drawings in which:
The preferred embodiment of the invention relates to a plate-type heat exchanger for effecting heat transfer between a first fluid to be cooled and a second fluid. The first fluid may preferably comprise a lubricating oil such as natural or synthetic engine oil, transmission oil or power steering oil or other fluid to be cooled, such as fuel. The second fluid may preferably comprise a liquid coolant for cooling the oil in the heat exchanger, for example a glycol coolant. Alternatively, at least one of the first and second fluids could be, for example, water, deionized water, or refrigerant, the fluid being in liquid, gaseous or two-phase form. In the following detailed description, the first and second fluids are referred to as the oil and the coolant, respectively and are in liquid form.
Terms such as “top”, “bottom”, “upward”, “downward”, “raised”, “recessed” and the like are used herein as terms of reference to describe features of the heat exchangers and heat exchanger plates according to the invention. It will be appreciated that these terms are used for convenience only, and the heat exchangers and heat exchanger plates according to the invention can have any desired orientation when in use.
The oil core plate 10 is now described in detail below with reference to
Plate 10 further comprises a coolant inlet opening 30 and a coolant outlet opening 32 together with, in the preferred embodiment shown in the drawings, a further opening 34 located between the oil inlet and outlet openings 22, 26. The coolant inlet and outlet openings 30, 32 are preferably located on opposite sides of the plate axis P, and are preferably located proximate the second end 28 of the plate 10. The further opening 34, the purpose of which will be explained later, is preferably located between the oil inlet and outlet openings 22, 26, preferably in close proximity to openings 22, 26 and preferably located along the plate axis P.
The base 12 of oil core plate 10 is provided with a plurality of protrusions and depressions in order to direct flow of the heat exchange fluids along its top and bottom surfaces 14, 16. In particular, the core plate 10 is provided with features which protrude in opposite directions from its top and bottom surfaces 14, 16. For consistency with the terms of reference used to describe the relative orientations of the plates, the features which protrude from the top surface 14 of the base 12 are described as “raised”, while those protruding from the bottom surface 16 are described as “depressed”. Again, it will be appreciated that these terms are used for convenience only. These features of the oil core plate 10 are now described in detail below.
As shown in
The first raised barrier portion 36 has a first end 40 proximate the oil inlet opening 22 and a second end 42 spaced from the oil inlet opening 22 toward the second end 28 of plate 10. An oil flow gap 44 is preferably provided between the second end 42 of first raised barrier portion 36 and the second end 28 of the plate 10, through which oil can flow between the oil inlet and outlet openings 22, 26, as explained in detail below.
As shown in
The first recessed barrier portion 46 has a first end 50 proximate the first end 24 of plate 10 and a second end 52 proximate the second end 28 of plate 10. Both the oil inlet and outlet openings 22, 26 are formed in the lower surface 48 of the first recessed barrier portion 46, with the oil inlet opening 22 preferably being located proximate the first end 50 of barrier portion 46 and the oil outlet opening 26 preferably being located intermediate the first and second ends 50, 52 of barrier portion 46.
Preferably, as shown in the drawings, the first recessed barrier portion 46 extends along the plate axis P, with the coolant inlet and outlet openings 30, 32 being located on opposite sides of the barrier portion 46. At least one coolant flow gap is provided, either through the first recessed barrier portion 46 or between the barrier portion 46 and the first end 24 of plate 10, through which the coolant can flow generally transversely as it flows between the coolant inlet and outlet openings 30, 32. In the preferred embodiment shown in the drawings, a first coolant flow gap 54 is provided between the first end 50 of the first recessed barrier portion 46 and the first end 24 of plate 10, through which the coolant can flow between the coolant openings 30, 32. To maximize the length of the coolant flow path along the bottom surface 16 of base 12, and thereby optimize heat transfer, the coolant flow gap 54 is spaced toward the first end 24 of plate 10 relative to the coolant openings 30, 32, and preferably the coolant flow gap 54 and coolant openings 30, 32 are located at opposite ends of plate 10.
The coolant core plate 60 is now described in detail below with reference to
Plate 60 further comprises a coolant inlet opening 80 and a coolant outlet opening 82 together with, in the preferred embodiment shown in the drawings, a further opening 84 located between the oil inlet and outlet openings 72, 76. The purpose of opening 84 will be explained in detail later. The coolant inlet and outlet openings 80, 82 are preferably located on opposite sides of the plate axis P, and are preferably located proximate the second end 78 of the plate 60. The further opening 84 is preferably located between the oil inlet and outlet openings 72, 76, preferably in close proximity to openings 72, 76 and preferably located along the plate axis P.
The base 62 of coolant core plate 60 is provided with a plurality of protrusions and depressions in order to direct flow of the heat exchange fluids along its top and bottom surfaces 64, 66. In particular, the core plate 60 is provided with features which protrude in opposite directions from its top and bottom surfaces 64, 66. As with the oil core plate, the features which protrude from the top surface 64 of the coolant core plate 60 are described as “raised”, while those protruding from the bottom surface 66 are described as “depressed”. Again, it will be appreciated that these terms are used for convenience only. These features of the coolant core plate 60 are now described in detail below.
As shown in
The second raised barrier portion 86 has a first end 90 proximate the first end 74 of plate 60 and a second end 92 proximate the second end 78 of plate 60. Both the oil inlet and outlet openings 72, 76 are formed in the upper surface 88 of the second raised barrier portion 86, with the oil inlet opening 72 preferably being located proximate the first end 80 of barrier portion 86 and the oil outlet opening 76 preferably being located intermediate the first and second ends 90, 92 of barrier portion 86.
Preferably, as shown in the drawings, the second raised barrier portion 86 extends along the plate axis P, with the coolant inlet and outlet openings 80, 82 being located on opposite sides of the barrier portion 86. At least one coolant flow gap is provided, either through the second raised barrier portion 86 or between the barrier portion 86 and the first end 74 of plate 60, through which the coolant can flow generally transversely as it flows between the coolant inlet and outlet openings 80, 82. In the preferred embodiment shown in the drawings, a first coolant flow gap 94 is provided between the first end 90 of the second raised barrier portion 86 and the first end 74 of plate 60, through which the coolant can flow between the coolant openings 80, 82. To maximize the length of the coolant flow path along the top surface 64 of base 62, and thereby optimize heat transfer, the coolant flow gap 94 is spaced toward the first end 74 of plate 60 relative to the coolant openings 30, 32, and preferably the coolant flow gap 94 and coolant openings 80, 82 are located at opposite ends of plate 60.
As shown in
The second recessed barrier portion 96 has a first end 100 proximate the oil inlet opening 72 and a second end 102 spaced from the oil inlet opening 72 toward the second end 78 of plate 60. An oil flow gap 104 is preferably provided between the second end 102 of second recessed barrier portion 96 and the second end 78 of the plate 60, through which oil can flow between the oil inlet and outlet openings 72, 76, as explained in detail below.
It will be appreciated from the drawings that the first raised barrier portion 36 of the oil core plate 10 and the second recessed barrier portion 96 of coolant core plate 60 correspond in size, shape and location so that their respective upper and lower surfaces 38 and 98 are in sealed contact with one another in the assembled heat exchanger. Preferred features of first raised barrier portion 36 are now described below with reference to the drawings. Except where noted to the contrary, the following discussion also applies to the second recessed barrier portion 96 of plate 60, and corresponding features of the second recessed barrier portion 96 are identified in the drawings with corresponding, primed reference numerals.
Firstly, it will be noted from
As shown in the drawings, the legs 108, 110 of first raised barrier portion 36 extend from the first portion 106 of barrier portion 36 toward the second end 28 of plate 10. Preferably, the terminal ends 112, 114 of legs 108, 110 are located at the second end 42 of barrier portion 36 and are proximate to the second end 28 of plate 10, with the oil flow gap 44 being defined by the distance (measured parallel to axis P) between the terminal ends 112, 114 of the legs 108, 110 and the second end 28 of plate 10.
Preferably, the legs 108, 110 extend along opposite sides of the oil outlet opening 26 for at least a portion of their lengths and are spaced apart so as to define a channel 116. With an axial distance from the terminal ends 112,114 of legs 108, 110 and the second end 28 of plate 10 preferably being less than an axial distance between the oil outlet opening 26 and the second end 28 of plate 10, the channel 116 provides a flow path extending from gap 44 toward the first end of plate 10, along which the oil must flow in order to reach the oil outlet opening 26. This has the effect of lengthening the flow path between the oil inlet and outlet openings 22, 26, thereby maximizing use of the plate surface area and optimizing heat transfer.
Preferably, the channel 116 is coplanar with the first fluid outlet opening 26 and with the first recessed barrier portion 46, i.e. it is recessed relative to the base 12. In the preferred embodiment shown in the drawings, the channel 116 preferably extends continuously along axis P from the oil outlet opening 26 to the second end 28 of plate 10.
As shown in the drawings, a pair of grooves 118 and 120 is formed in the top surface 14 of plate 10. Each groove 118,120 extends along a side of one of the legs 108, 110 opposite the channel 116. Preferably, the grooves 118, 120 are coplanar with the channel 116 and each have an end communicating with the channel 116 at the terminal end 112 or 114 of one of the legs 108 or 110.
Lastly, the base 12 of oil core plate 10 is provided on its top surface 14 with a pair of upstanding bosses 122, 124 having respective upper surfaces 126, 128 in which the coolant inlet and outlet openings 30, 32 are formed. In the preferred embodiment shown in the drawings, the upper surfaces 126,128 of bosses 122, 124 are raised relative to the base 12 and relative to the first raised barrier portion 36, with the corresponding coolant inlet and outlet openings 80, 82 of the coolant core plate 60 being coplanar with the base 62 thereof. It will, however, be appreciated that this is not necessarily the case. For example, the upper surfaces 126, 128 of raised bosses 122,124 could be coplanar with the upper surface 38 of raised barrier portion 36, and the coolant core plate could be provided with corresponding recessed bosses (not shown) which come into sealed contact with the raised bosses 122,124.
It will further be appreciated from the drawings that the first recessed barrier portion 46 of the oil core plate 10 and the second raised barrier portion 86 of coolant core plate 60 correspond in size, shape and location so that their respective lower and upper surfaces 48 and 88 are in sealed contact with one another in the assembled heat exchanger. Preferred features of first recessed barrier portion 46 are now described below with reference to the drawings. Except where noted to the contrary, the following discussion also applies to the second raised barrier portion 86 of plate 60, and corresponding features of the second raised barrier portion 86 are identified in the drawings with corresponding, primed reference numerals.
It will be noted that the first recessed barrier portion 46 is comprised of a plurality of bosses, including a first boss 130 in which the oil inlet opening 22 is formed and a second boss 132 in which the oil outlet opening 26 is formed. In preferred embodiments where the plate 10 includes a further opening 34, the barrier portion 46 further comprises a third boss 134 located between and in close proximity to the first and second bosses 130,132. The third boss 134 surrounds the further opening 34 and is located radially inwardly of the approximately circular rib comprising the first portion 106 of the first raised barrier portion 36, discussed above.
As shown in the drawings, the first coolant flow gap 54 is located between the first boss 130 and the first end 24 of plate 10. In addition a second coolant flow gap 136 is located between the first boss 130 and the third boss 134, and a third coolant flow gap 138 is located between the second boss 132 and the third boss 134. The first gap 54 is preferably wider than the second and third gaps 136, 138 so that most of the coolant flowing from the coolant inlet opening 30 to the coolant outlet opening 32 will be forced to flow around the first boss 130, thereby maximizing the distance travelled by the coolant and maximizing use of the plate surface area, thereby optimizing heat transfer.
As shown in the drawings, the second boss 132 is elongate and extends axially from the oil outlet opening 26 to the second end 28 of plate 10, thereby preventing short circuit flow of coolant across the plate between inlet and outlet openings 30, 32. It will also be appreciated that the second boss is coextensive with the recessed channel 116, discussed above, which is formed in the top surface 14 of plate 10.
The first recessed barrier portion 46 further comprises a pair of legs 140, 142 to help direct flow of the coolant. These legs 140, 142 extend alongside and in close proximity to the second boss 132 and are coincident with the grooves 118,120 on the other side of the plate 10. Each of the legs 140, 142 has a free end which terminates proximate the third coolant flow gap 138 and an opposite end which is joined to a side of the second boss 132. The legs 140, 142 are spaced from the second boss 132 by a pair of narrow grooves 144, 146, comprising the undersides of the legs 108, 110 formed in the top surface 14 of plate 10. The grooves 144, 146 are preferably coplanar with a groove 148 surrounding the third boss 134, which forms the underside of the first portion 106 of the first raised barrier portion 36, described above.
Referring now to
The bases 12, 62 of alternating oil and coolant core plates 10, 60 are in spaced relation to one another to define a series of alternating oil flow passages 152 and coolant flow passages 154. Oil flow passages 152 are formed between the top surfaces 14 of oil core plates 10 and the bottom surfaces 66 of upwardly adjacent coolant core plates 60. Similarly, coolant flow passages 154 are formed between the top surfaces 64 of coolant core plates 60 and the bottom surfaces 16 of upwardly adjacent oil core plates 10.
It will be seen from the drawings of heat exchanger 150 that the first raised barrier portions 36 of the oil core plates 10 are in sealed contact with the corresponding second recessed barrier portions 96 of an upwardly adjacent coolant core plate 60, the barrier portions 36, 96 being in sealed contact along their upper and lower surfaces 38, 98, respectively. As mentioned above, the barrier portions 36, 96 are preferably identical in size and shape and are of sufficient height so that each raised element making up barrier portion 36 (i.e. first portion 106 and legs 108, 110) is in sealed contact with a corresponding recessed element of barrier portion 96 (i.e. first portion 106′ and legs 108′, 110′). Furthermore, the oil flow gaps 44 and 104 of the respective oil and coolant core plates 10, 60 are aligned, as are the channels 116, 116′ and the grooves 118,118′, 120 and 120′ of respective plates 10, 60.
It will also be seen that the second raised barrier portions 86 of the coolant core plates 60 are in sealed contact with the corresponding first recessed barrier portions 46 of an upwardly adjacent oil core plate 10, the barrier portions 86, 46 being in sealed contact along their upper and lower surfaces 88, 48, respectively. The barrier portions 46, 86 are preferably identical in size, shape and height so that each recessed element making up barrier portion 46 (i.e. first boss 130, second boss 132, third boss 134 and legs 140, 142) is in sealed contact with a corresponding raised element of barrier portion 86 (i.e. first boss 130′, second boss 132′, third boss 134′ and legs 140′, 142′). Furthermore, the first coolant flow gaps 54 and 94 of the respective oil and coolant core plates 10, 60 are aligned, as are the second coolant flow gaps 136, 136′, the third coolant flow gaps 138, 138′ and the narrow grooves 144, 144′, 146 and 146′ of the respective plates 10, 60.
It will also be appreciated that the bosses 122, 124 formed in the top surface 14 of each oil core plate 10, in which the coolant inlet and outlet openings 30, 32 are formed, are sealed along their upper surfaces 126, 128 to the bottom surface 66 of an upwardly adjacent coolant core plate 60. Furthermore, the plates 10, 60 are sealed together with the openings of each oil core plate 10 (i.e. oil inlet opening 22, oil outlet opening 26, coolant inlet opening 30, coolant outlet opening 32, further opening 34) being in alignment with the corresponding openings of each coolant core plate 60 (i.e. oil inlet opening 72, oil outlet opening 76, coolant inlet opening 80, coolant outlet opening 82, further opening 84).
Where the plates are made of a metallic material, they may be provided with a brazing filler metal in the form of a cladding, a coating or shim plates so that, after assembly of the plurality of oil core plates 10 and the plurality of coolant core plates 60 as described above, the assembled plates 10, 60 may be disposed in a brazing furnace or other suitable heating means thereby to provide the above-described sealing contact between the plates 10, 60. Metallic plates can also be joined by alternate suitable means such as welding, adhesive bonding, or mechanical assembly using sealing gaskets. Non-metallic plates can be joined by other means, such as ultrasonic welding.
Ends plates 156 and 158 are schematically shown in the drawings for sealing the ends of the plate stack and connecting it to the oil and coolant systems.
As shown in
The upper end plate 156 is also provided with an oil return opening 180 through which filtered oil is returned to the engine block 168 via the aligned further openings 34, 84 of the stacked plates 10, 60 which together form an oil return passage 182 which is sealed from the oil flow passages 152. The oil return passage 182 is in communication with an oil return opening 184 in the lower end plate 158 and with an oil return passage 186 of the engine block 168.
In operation, oil from engine block 168 enters the heat exchanger 150 through the oil inlet opening 172 in the lower end plate 158 and then flows into one end of the aligned oil inlet openings 22, 72. Since the other end of the aligned openings 22, 72 is blocked by upper end plate 156, the oil is forced to flow through the oil flow passages 152 as indicated in chain-dotted lines in
The oil flowing from the heat exchanger through the aligned oil outlet openings 26, 76 flows through the oil outlet opening 176 in the upper end plate 156 and into oil filter 170 where it passes through a filter medium 188 and enters a perforated central tube 190 for return to the engine block 168 through the oil return passage 182 and the oil return openings 180, 184. The flow of oil through the engine block 168, heat exchanger 150 and oil filter 170 is indicated by arrows in
In the alternative, the oil flow may be reversed so that it is filtered before being cooled by heat exchanger 150. In this embodiment, the oil flows from passage 186 of engine block 168 into the passage 182 of heat exchanger 150. The oil flows through passage 182 and enters the oil filter 170 to be filtered. The filtered oil then enters the heat exchanger 150 through opening 176 in upper end plate 156 and exits the heat exchanger through the opening 172 in the lower end plate 158, returning to engine block 168 through passage 174.
In the preferred heat exchanger 150 shown in
As shown in
The heat exchanger 150 according to the invention thus achieves a high rate of heat transfer between the oil and the coolant. It will, of course, be appreciated that the openings 32, 82 could be the coolant inlet openings with the openings 30, 80 being the coolant outlet openings. Furthermore, the openings 26, 76 could function as the oil inlet openings, with the openings 22, 72 functioning as the oil outlet openings.
It will be appreciated that the height of each oil flow passage 152 and the height of each coolant flow passage 154 is partly dependent on the extent of the nesting of the alternate plates 10, 60 and therefore is partly dependent on the angle of inclination of the flanges 20, 70. It will also be appreciated that the heights of the flow passages 152, 154 are also partly dependent on the heights of the barrier portions 36, 46, 86, 96 and the heights of bosses 122, 124.
Turbulisers which may be of conventional form, such as the turbulisers 60 of U.S. Pat. No. 6,244,334 issued on Jun. 12, 2001 to Wu, et al., are preferably disposed in one or more of the oil flow passages 152 and may also be disposed in one or more of the coolant flow passages 154, these turbulisers serving to disrupt the oil or coolant flow in each of the oil or coolant flow passages 152, 154 in which they are installed and to disturb the boundary layers of the oil or coolant flow at the surfaces of the plates 10, 60, thereby improving the efficiency of heat transfer from the oil to the coolant in the heat exchanger 150. For clarity, these turbulisers are shown only in
Instead of using turbulisers 178, 180, the base 62 of one or more of the coolant core plates 60 may be formed with spaced protrusions such as ribs and/or dimples, similar to those shown in FIGS. 1 and 2 of U.S. Publication No. 2004/0040697 A1 (St. Pierre et al.) published on Mar. 4, 2004 and incorporated herein by reference in its entirety.
Although the invention has been described in connection with certain preferred embodiments, it is not limited thereto. Rather, the invention includes all embodiments which may fall within the scope of the following claims.
