MXPA99002884A - Construction of aluminum head - Google Patents

Abstract

A heat exchanger is provided which includes a first extruded aluminum head, spaced apart and disposed essentially parallel to a second extruded aluminum head. The first and second heads include a plurality of parallel passages projecting through a longitudinal axis. The passages are fluidly interconnected at least by a transverse drilled hole projecting essentially perpendicular to the longitudinal axis. A core structure is clamped between the first and second heads including a plurality of heat conduits and radiating fins that surround the fluid passages. A bypass valve structure communicates fluidly with the heads and core structure while providing an independent alternating path. Preferably, the bypass structure responds to temperature and / or fluid pressure, to direct fluid flow either inside or outside the core structure of the heat exchanger. In one form, the bypass valve structure is fixedly fastened to one of the heads while in a second embodiment, the bypass valve structure is removably attached to a plate member attached to one of the headstock.

Description

CONSTRUCTION OF ALUMINUM HEAD Background of the Invention Cross Reference to Related Request The present corresponds to a continuation-in-part of the U.S. Patent Application. No. 09 / 049,742 filed on March 27, 1998. 1. - Technical Field The present invention relates in general to heat exchangers and more particularly to heat exchangers having an extruded aluminum head construction and a temperature response bypass structure. 2. Background Thermo-exchangers of the type of fins and tubes, are used to cool and transfer heat between two fluids. In general, one of the fluids is circulated internally through ducts that are provided in the core of the heat exchanger and the other is passed on the outside of the associated heat radiating ducts and fins. These heat exchangers are commonly used in heavy construction machinery as well as in other devices that use cooling oils, hydraulic fluid or the like.

In these applications, the fluid can exert a high level of. The fluid under pressure can damage the head portion or core portion of the heat exchanger if any portion is not designed properly. a relatively high viscosity when cooled such as when starting the equipment and thinning as it is heated during use.This high viscosity can cause higher than desired pressure in the inlet head of these heat exchangers, due to the viscous resistance of the fluid flow Through the relatively small passages in the core of the heat exchanger, the resistance can also prevent a sufficient quantity of fluid from circulating through the system, which in an extreme case can result in excessive wear on the equipment. , it would be convenient to provide an extruded head for a heat exchange which supports extreme internal pressures. It would also be convenient to provide a temperature response bypass means to allow the high viscosity cold fluid to bypass the core of the heat exchanger. These bypass means can also operate to avoid unnecessary cooling of the fluid, thereby helping the apparatus reach a steady state operating temperature more rapidly. SUMMARY OF THE INVENTION The foregoing and other objects are provided by a heat exchanger including a first extruded aluminum head spaced and exposed essentially parallel to a second extruded aluminum head. The first and second heads include a plurality of parallel passages extending through a longitudinal axis. The passages are interconnected in fluid form at least by a transversely drilled transverse perforation, which extends essentially perpendicular to the longitudinal axis. A core structure is clamped between the first and second headers and includes a plurality of restricted fluid conduits and thermal radiating fins surrounding the fluid conduits. An optional valve bypass structure fluidly communicates the head and core structure while providing an independent alternating path. Preferably, the bypass structure responds to the fluid temperature to direct the flow of fluid either to or to the outside of the heat exchanger core structure.

BRIEF DESCRIPTION OF THE DRAWINGS In order to appreciate the way in which the advantages and objectives of the invention are obtained, a more particular description of the invention will be achieved by reference to its specific embodiments which are illustrated in the accompanying drawings. It is understood that these drawings only illustrate preferred embodiments of the present invention and therefore should not be construed as limiting the scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: Figure 1 is a front elevational view of a heat exchanger according to the present invention, having an extruded aluminum head that includes a plurality of parallel passages, which project longitudinally throughways interconnected at least by a transverse perforation, all in accordance with the present invention; Figure 2 is an end view of the heat exchanger of Figure 1; Figure 3 is a side elevational view of the heat exchanger of Figure 1 illustrating the dashed line passages; Figure 4 is a sectional view of the heat exchanger of the present invention taken on line 4-4 of Figure 2; Figure 5 is a sectional view of the heat exchanger of the present invention taken on line 5-5 of Figure 4, - Figure 6 is a fragmentary front elevation view similar to that of Figure 1, but illustrating a alternate embodiment of the present invention including a branch structure that responds to the temperature provided therein; Figure 7 is an enlarged fragmentary detail view of the bypass structure of Figure 6, Figure 8 is a sectional view similar to Figure 5 but illustrating an alternate embodiment thereof, Figure 9 is a sectional view; similar to that of Figures 5 and 8 but illustrating another embodiment thereof, - Figure 10 is a sectional view similar to that of Figure 6 but showing another embodiment of the present invention: Figure 11 is a similar view to Figure 3 but showing the embodiment of Figure 10; Figure 12 is an end view of the embodiment of Figure 10; Figure 13 is an enlarged elevation view of the plate member to which the valve housing is secured; Figure 14 is a sectional view of the plate member shown in Figure 13, the section taken on line 14-14; Figure 15 is a sectional view of the bypass valve housing, the section is taken on line 15-15 of Figure 11; Figure 16 is another sectional view of the valve housing of Figure 15, the section taken on line 16-16; and "Figure 17 is another sectional view of the valve housing of Figure 15, the section is taken on line 17-17 DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The present invention is directed to a suitable heat exchanger to withstand high cylinder pressures contained therein. The heat exchanger includes a pair of opposed and spaced aluminum extruded heads that include a plurality of parallel passages extending through the longitudinal axis. The passages are fluidly interconnected at least by a drilled transverse bore extending essentially perpendicular to the longitudinal axis. An optional branch structure communicates fluidly with the first head while providing an independent alternating path. In a preferred embodiment of the present invention, the bypass structure includes a bypass valve that responds to temperature. As such, fluid of high viscosity and low temperature is allowed to derive the core of the heat exchanger, thereby reducing the time required for the fluid to reach a normal operating temperature. Turning now to the Figures of drawings, a first preferred embodiment of the heat exchanger 10 according to the present invention is illustrated in Figure 1. The heat exchanger 10 includes a first head 12, a second head 14 spaced from the first head 12 and arranged in substantially parallel. A pair of spaced frame members 16 and 18 extend between them adjacent opposite ends of the first and second headers 12 and 14. A core structure of heat exchanger 20 is disposed between the first and second headers 12 and 14 and is in communication fluent with them. The core structure includes a pair of relatively small diameter fluid conduits 22 that extend generally perpendicular to the longitudinal axis of the first and second headers 12 and 14. The fluid conduits 22 are surrounded by a plurality of fins 24 projecting substantially. parallel to the longitudinal axis of the first and second heads 12 and 14. Preferably, the core structure 20 will be of the stacked fin and tube type, as described in US Pat. Nos. 3,430,692 and 3,601,878, the descriptions of which are incorporated herein by reference. The first head 12 has an inlet opening 26 adjacent an end that is adapted to be connected to a fluid supply line (not shown). The first head 12 has a similar outlet opening 28 adapted to be connected to a discharge line (also not shown). Now with reference also to Figures 2 and 3, a pair of elbow-shaped mounting brackets at L 30 and 32, are fixed by welding or other conventional means to an outer edge of the second head 14. Similarly, a pair of mounting brackets 34 and 36 are fixed by welding or other conventional means to an outer edge of the first head 12. Still with reference to Figures 1 to 3, the first and second heads 12 and 14 include three parallel passages 42 projecting substantially parallel to the longitudinal axis of the first and second heads 12 and 14. The passages 42 fluidly interconnect the inlet opening 26 and the outlet opening 28 by the heads 12 and 14 and the core structure 20. Preferably, each of the heads 12 and 14 are formed to Starting from aluminum through an extrusion process The extruded aluminum material having the desired number of longitudinally projecting fluid passages 42, is easily cut to the desired length required for the intended exchanger and its opposite ends are closed by convenient plate welding. Because the respective passages 42 are interconnected by perforations 50, the exchange between them in the endplates is not of interest. Additionally, when constructing a two-step heat exchanger such as that shown in Figures 1 to 3, two substantially equal lengths of head material are joined in conjunction with a divider plate 44 welded therebetween. Alternatively, it may be possible to extrude the head 12 in such a way that it forms the dividing plate 44 integrally, if desired. As such, the conduits 42 of the first head 12 are divided into supply conduits 46 close to the inlet opening 26 and discharge conduits 48 near the outlet opening 28. Now with reference to Figures 4 and 5, a more detailed view of the second head 14.

While the following description is directed to the second head 14, a person skilled in the art will appreciate that, except for the splitter 44, the first head 12 is substantially similar to the second head 14- and that the following description equally applies. Each of the passages 42 of the second head 14 is in fluid communication with an adjacent passage 42 by a transverse bore 50 projecting essentially perpendicular to the longitudinal axis of the second head 14. Preferably, the transverse bore 50 is formed by transverse drilling of the second extruded head 14. The end of the transverse bore 50 at the outer edge of the second head 14 is sealed by a convenient plug 52 welded in place to prevent leakage of the second head 14._ Each of the conduits 42 communicates in fluid form with a plurality of fluid conduits 22 arranged perpendicularly and forming part of the core structure. As best seen in Figure 5, each of the fluid conduits 22 includes a bifurcated inlet 54 in a pair of parallel pipes 56, which project through the structure of the core 20 to the first head 12 (see Figure 1) . Although not illustrated in detail, a person skilled in the art will appreciate that the pair of parallel pipes 56 converge at an opposite end toward a single outlet 58 (Figure 1) communicating with the first head 12. It will be appreciated that the terms "in" and "out" as used herein are interchangeable and simply indicative of the direction of fluid flow. In the embodiment illustrated in Figure 5, the plane defined by the pair of parallel pipes 56 is parallel to the frame members 16 and 18, thus allowing inclusion of a greater number of flow paths between the two heads for a size of certain envelope. As such, a short and wide heat exchanger can be provided while still providing significant surface area for heat exchange. In operation, fluid such as oil is provided to the inlet opening 26 by a supply line and enters the supply passages 46 of the first head 12. When the fluid enters the first of the supply passages 46 (i.e. 46 communicates with the inlet opening 26), the fluid fills the remaining supply passages 46 in the first head 12 as it propagates through one or more transverse perforations 50. This ratio can be controlled (i.e., improved or reduced) by changing the diameter and / or number of transverse perforations 50 that are provided, although it is preferred to incorporate a sufficient amount and / or sufficiently large diameter perforations to ensure substantially free flow between and equal pressure in each of the passages 42. Of the delivery passages 46, the fluid is propagated through the fluid conduits -22, in communication with the second head 14. When it enters the second head 14, the fluid l the passages 42 therein formed by transverse perforation 50. The fluid then propagates from the second head 14 through the remaining fluid conduits 22, to the discharge passages 48 formed in the first head 12. From the discharge passages 48. , the fluid is discharged from the heat exchanger 10 through the outlet opening 28 and a discharged discharge line. As the fluid travels through the conduits 22 of the core structure 20, its temperature is reduced as the heat is conducted and transferred by convection from the fluid to the walls of the conduits 22 and ~ to the fins 24. It should be noted that the heat exchanger 10 as illustrated and described is a two-step heat exchanger (ie the fluid circulates through the core twice). However, if desired the heat exchanger 10 can be easily manufactured as a one-way exchanger, by simply removing the divider 44 from the head 12 and moving the outlet fitting 28 to the other head 14. Alternately, a multi-step heat exchanger can be easily manufactured by providing any number of splitters 44 properly positioned in each of the heads 12 and 14. Turning now to Figure 6, an alternate embodiment of the present invention is illustrated, this embodiment is substantially similar to the embodiments shown in Figures 1 to 5, except that the plurality of fluid conduits 22a including the pair of parallel pipes 56a have been rotated 90 degrees relative to the horizontal such that the plane defined by the pair of parallel pipes 56a , is perpendicular to the frame members 16a and 18a. This structure is preferred, since it allows the longitudinal spacing between openings 22 to be increased. In addition, the inlet opening 26, the outlet opening 28 and the bypass openings 38 and 40 of the first embodiment, have been combined into a structure bypass valve 58. Bypass valve 58 is operable to direct fluid flow within or independent of exchanger 10a in response to either pressure or fluid temperature or both. As best seen in Figure 7, the bypass valve structure in response to temperature and pressure 58, includes a bypass valve inlet 60 that communicates fluidly with the inlet opening 26a and a valve chamber 62. Similarly , the bypass valve structure 58 includes a bypass valve outlet 64 that communicates fluidly with the outlet opening 28a and the valve chamber 62. A thermal response valve 65 is disposed within the valve chamber 62 and includes a valve member 66 operable to open and close the passage defined between the inlet 60 and the outlet 64. The valve 65 is preferably of the type that includes a wax motor operable to move the valve structure 66 in a position such that , the communication between the inlet 60 and the outlet 64 is prevented by the valve chamber 62, when the fluid exceeds a predetermined temperature. The wax motor is placed in the fluid flow path through the chamber 62, to be responsive to the fluid temperature. Additionally, the valve 65 may include a bypass spring operable to resiliently bypass the valve member 66 to a closed position but which allows communication between the inlet 60 and the outlet 64 by the chamber 62, when the valve member (íTse moves within of an open position in response to an increase in the differential pressure between the inlet 60 and outlet 64 over a predetermined level When the bypass valve 65 is open, the fluid accesses the inlet of the bypass valve 60 from a line of supply and propagates through the valve chamber 62 and exits through the bypass valve outlet 64. Although the inlet opening 26a is open in this mode, the majority of the fluid derives the fluid opening 26 due to the flow of restricted fluid that is allowed through the opening 26a as well as the resistance to the aggregate flow from the core 20. In this way, since the passage through of the bypass valve 58 provides the path of least resistance, the fluid travels through and drifts the heat exchanger 10. On the other hand, when the bypass valve 65 is closed, i.e. the valve member 66 engages the valve seat, the fluid flows through the bypass valve inlet 60 and into the inlet opening 26a. After passing through the first head 12, the structure of the core 20, the second head 14 and returning to the first head 12, the fluid propagates through the outlet opening 28a and passes through the outlet of the bypass valve 64 to a download line. In this way, when the fluid is insufficiently hot (and thus too viscous) it can be directed away from the heat exchanger 10. Turning now to Figure 8, an alternate mode of head, as the first head 12b is illustrated. Although the first head 12b is illustrated, it can be appreciated that the second head 14 can easily replace it. In contrast to the previous embodiments, the first head 12b includes two parallel passages of enlarged diameter 42b, projecting through the longitudinal axis. The passages 42b communicate with conduits 22b and are interconnected by a transverse perforation 50b which is sealed with a convenient cap 52b. According to this embodiment, a narrower head 12b is provided. Still another embodiment of the present invention is illustrated in Figure 9. In this embodiment, a head, such as the first head 12c, includes 6 parallel passages of relatively small diameter 42c, extending through the longitudinal axis. The passages 42c are fluidly interconnected by a transverse perforation 50c sealed at an outer edge of the head 12c with a convenient plug 52c. The passages 42c also communicate with the conduits 22c. As can be appreciated, the embodiments illustrated in Figures 5, and 9 demonstrate that the number and diameter of passages 42c in the head 12c can be controlled by a designer in accordance with the particular needs of the application in which the present invention is incorporated, such as fluid viscosity and available space as well as the required cooling capacity. For example, the modality illustrated in Figure 9 is well suited for use in a large space, but probably short. Another embodiment of the present invention is illustrated in and will be described with reference to Figures 10 to 12. In this embodiment, the heat exchanger 70 is a two-pass heat exchanger, generally similar to the heat exchangers 10 and 10a described above and includes a structure of core 72 preferably of the type stacked fins and tubes having a pair of heads held at their opposite ends (only the input / output head 74 is illustrated). The head 74 and the return head (not shown) are of the extruded construction described above, with the head 74 which is substantially identical to the head 12a except for the placement and connection shape of the bypass valve structure 76 and the location of the entrance and exit openings that are provided there. As shown, the inlet and outlet openings 78 and 80 are provided in immediate proximity to each other in the side wall portion 82 of the head 74. A plate member 84 is attached to the side wall portion 82 and includes a pair of spaced openings 85, 87 that are placed in aligned relation with respective inlet and outlet openings 78 and 80. Preferably, the plate member 84 is secured to the side wall portion 82 to form a fluid tight connection such as by welding , although other convenient means for securing the plate 84 can be employed. The bypass valve structure 76 is generally similar to the bypass valve structure 58 and includes a housing 86 having an inlet passage 88 opening to a valve chamber. 90 which is provided in the housing 86. A passage projecting transversely 92 intersects the entrance passage 88 and opens at its inner end a passage extending further ally 94, which in turn opens outward of the housing 86 in a position to be aligned with the opening 85 in the plate member 84 when the housing 86 is clamped there. An exit aperture 96 is also provided projecting inwardly in a spaced relation substantially parallel to the entry passage 92 and opening at its inner end to a transversely projecting passage 98. The transversely projecting passage 98 extends through the valve chamber 90 and has its outer end sealed by a convenient plug 100. Similarly, the outer end of the transversely extending passage 92, it is also sealed by a convenient plug 102. A laterally extending passageway 104 projects in spaced relation parallel to the laterally extending passageway 94 from the transversely extending passageway 98 and opens outwardly from the housing 86 in a position for align with the opening 87 in the plate member 84, when the housing 86 is clamped there. A valve member 106 is removably held in the housing 86 and projects to the valve chamber 90. The valve member 106 includes a valve member 108 engageable with a valve seat 110 positioned at the junction between the inlet passage 88. and the valve chamber 90, to prevent fluid communication between the passage 188 and the valve chamber 90. Preferably, the valve member 106 will be substantially identical to the valve 65 described above and will include a wax motor operative to move the element. valve between open and closed positions in response to fluid temperature flowing through heat exchanger 70. Housing 86 is preferably removably attached to plate member 84 by a plurality of threaded fasteners 112, 114 and 116. O-rings? Convenient may be employed in joining the passages 94 and 104, with the passages 87 and 85 in the plate member 84 to secure a relationship seal hermetic to safe fluid between them.

In operation, a fluid supply line is connected to the inlet opening 88 and a fluid discharge line is connected to the outlet opening 96. When the operation of the equipment in which the heat exchanger is installed is started and the fluid is cold, the wax motor of valve member 106 will have operated to move valve member 108 out of seat 110, thereby allowing fluid to flow directly from inlet 88 to outlet 96 through valve chamber 90, in this way deriving the core structure 72. As the fluid begins to heat during continuous operation, the valve member 106 will begin to close in this manner increasing the restriction in the flow through the valve chamber 90, which will result in increase volume of fluid directed through the heat exchanger core 72. Once the fluid temperature has risen to the desired operating level, the valve 106 close completely, thus directing all fluid flow through the heat exchanger core. The wax motor of the valve 106 is positioned to be able to continuously detect the fluid temperature as it leaves the core of the heat exchanger and in this way in case the temperature drops below the desired level for some reason, the valve element 108 it will open again to allow it to derive some fluid to the core structure thereby reducing its cooling. It will be noted that the valve member 106 can also be operated to equally provide a pressure response bypass feature. In this way, in case that for some reason the pressure drop through the core structure as detected between the inlet and the outlet increases above a pre-determined level, this pressure differential will operate to open the valve element 108, to allow the fluid to bypass the core structure in this way allowing continuous operation of the equipment. It will be noted that while the embodiments of Figures 10 to 17 are shown and described using a head having three fluid passages, heads having a greater or lesser number of passages for fluid can easily be substituted. The use of a secure valve structure in a "removable" manner as described above, offers the advantage of increased flexibility as well as reduced non-operating time in the event of a failure, for example, in case it is convenient for some reason to withdraw the bypass valve structure due to some operational aspects, the valve housing 86 can be easily removed by removing the retaining clips 112, 114, 116. Subsequently, a second plate having convenient openings for connection to the lines of the inlet fluid and output, it can be replaced by the valve housing 86 and the equipment then operated without the bypass feature.Also, in the event that for some reason the valve member 106 fails, the entire structure can be easily replaced or, if a replacement valve member is not available, a second convenient plate without the bypass structure, can settle in your site. Additionally, the modular valve housing structure described above can facilitate the manufacture of the heat exchanger in which the entire heat exchanger can be assembled and subjected to a tin-welding process, to ensure a fluid-tight seal between the various components after which the Valve structure can be easily assembled. In this manner, the present invention provides a heat exchanger including extruded aluminum heads having a plurality of parallel passages extending through a longitudinal axis. The parallel passages are interconnected fluidly by a transverse perforation drilled through the head. A bypass valve external to the heat exchanger, provides a fluid passage independent of the core structure of the heat exchanger. In a preferred embodiment, the bypass valve responds to temperature and pressure of the fluid passing through. Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of ways. Therefore, while this invention has been described in connection with particular examples thereof, the actual scope of the invention should not be thus limited since other modifications will be apparent to the practitioner with skill in the art before a study of the drawings, specification and following claims.

Claims (1)

1. CLAIMS 1.- A heat exchanger, characterized in that it comprises: a first head including a plurality of parallel passages extending through a longitudinal axis, the passages are fluidly interconnected at least by a transverse perforation extending essentially perpendicular to the longitudinal axis; a second head spaced from the first head and including a plurality of parallel passages, projecting through a longitudinal axis, the passages are fluidly interconnected at least by a transverse bore that extends essentially perpendicular to the longitudinal axis; and a core structure held between the first and second heads, the core structure includes a plurality of fluid passages extending between the first and second thermal radiating heads and fins surrounding the plurality of fluid passages. 2. - The heat exchanger according to claim 1, wherein the first and second heads further comprise extruded aluminum members. 3. The heat exchanger according to claim 1, characterized in that the transverse perforations also comprise lateral passages drilled through the first and second heads. . - The heat exchanger according to claim 1, characterized in that it also comprises a bypass mechanism that provides a passage inside and independent of the core structure. 5. - The heat exchanger according to claim 4, characterized in that the bypass mechanism includes a valve housing, the valve housing is removably attached to one of the first and second heads. 6. The heat exchanger according to claim 4, characterized in that the bypass mechanism further comprises a bypass valve that responds to temperature to change between an open and a closed mode. 7. - The heat exchanger according to claim 1, characterized in that the first head is bifurcated into a plurality of parallel supply conduits and a plurality of parallel discharge conduits. 8. - The heat exchanger according to claim 1, characterized in that the fluid conduits further comprise an inlet and an outlet and a pair of parallel pipes extending between them. 9. - The heat exchanger according to claim 8, characterized in that the pair of parallel pipes form a plane perpendicular to the plane defined by a pair of frame members projecting between ends of the first and second heads. 10. - The heat exchanger according to claim 8, characterized in that the pair of parallel pipes form a plane parallel to a plane defined by a pair of frame members projecting between ends of the first and second heads. 11. The heat exchanger according to claim 1, characterized in that the transverse perforations are sealed at an outer edge of the heads by a plug. 12. - The heat exchanger according to claim 1, characterized in that the plurality of parallel passages further comprises two parallel passages. 13. - The heat exchanger according to claim 1, characterized in that the plurality of parallel passages extends through the first "and" second heads and further comprises three parallel passages. 14. - The heat exchanger according to claim 1, characterized in that the plurality of parallel passages further comprises six parallel passages. 15. Method for producing a heat exchanger, characterized in that it comprises: extruding .aluminum in a first head having a plurality of parallel passages extending through a longitudinal axis; providing a transverse perforation through the first head, for fluidly interconnecting the plurality of parallel passages; and coupling a core structure between the first head and a second head, the core structure includes a plurality of fluid passages communicating with the plurality of parallel passages and thermal radiating fins surrounding the plurality of fluid passages. 16. - The method according to claim 15, characterized in that the step of providing a transverse perforation further comprises: drilling transversely drilling the transverse to the first head; and sealing one end of the transverse perforation on one edge of the first head with a stopper. 17. - The method according to claim 15, characterized in that it further comprises: extruding the aluminum in the second head having a plurality of parallel passages extending through a longitudinal axis. 18. - The method according to claim 15, characterized in that it further comprises: coupling a bypass mechanism to the first head to provide a fluid path inside and independent of the first head. 19. - The method according to claim 18, characterized in that the bypass mechanism responds to temperature to change between an open and a closed mode. 20. The method according to claim 15, characterized in that the plurality of conduits further comprises an inlet and an outlet and a pair of parallel pipes projecting between them forming a plane parallel to a plane defined by a pair of limb members. frame extending between ends of the first and second heads. 21. The method according to claim 15, characterized in that the plurality of conduits further comprises an inlet and an outlet and a pair of parallel pipes extending between them forming a plane perpendicular to a plane defined by a pair of limb members. frame projecting between ends of the first and second heads. 22. A heat exchanger, characterized in that it comprises: a core structure, - first and second heads subject to opposite ends of the core structure, at least one of the first and second heads includes an elongated member having a plurality of first spaced longitudinally extending fluid passages, each of the first passages is closed at opposite ends of the elongate member and second passages for fluid, operative to place the first passages for fluids in fluid communication with each other. 23. - The heat exchanger according to claim 22, characterized in that - the second passages for fluid are formed in the elongate member. 24. - The heat exchanger according to claim 22, characterized in that opposite ends of each of the first passages for fluid are closed by means of plugs that are sealingly fastened. 25. The heat exchanger according to claim 22, characterized in that one of the first and second headers includes a second one-piece member having a plurality of third passages for fluids extending longitudinally, substantially parallel therein, each of the third passages for fluid are closed at opposite ends and third passages for operative fluid to place the first passages for fluid in fluid communication with each other, opposite ends of the first and second elongate members are held together. 26. The heat exchanger according to claim 22, characterized in that the first elongate member has an inlet opening communicating with the first passages for fluid, which is provided adjacent to the opposite end and the second elongated member has an outlet opening that communicates with the third passages for fluid that are provided adjacent to the opposite end. 27. The heat exchanger according to claim 26, characterized in that it also comprises a bypass valve structure that is provided in the head, the bypass valve structure is operative to allow the fluid to derive the core structure when the fluid is below a pre-determined temperature and to direct- the flow of fluid through the core structure when the fluid is at or above a predetermined temperature. ~ The heat exchanger according to claim 27, characterized in that the bypass valve structure is also operative to allow the fluid to derive the core structure in response to a pressure differential between the outlet and inlet openings on a default pressure. 29. The heat exchanger according to claim 27, characterized in that the bypass valve structure is removably attached to the head. 30. - The heat exchanger according to claim 29, characterized in that the head includes a plate member subject to first and second elongated members, the plate member includes openings aligned with each of the inlet and outlet openings, the bypass valve structure is removably attached to the plate member. 31. The heat exchanger according to claim 30, characterized in that the bypass valve structure includes a first passage for fluid entry communicating with the entrance passage through one of the openings in the plate member, an exit passage of fluid in fluid communication with the exit passage by another opening in the plate member, a bypass passage for placing the fluid inlet passage in fluid communication with the passage for fluid outlet and a valve member that is operative for selectively allow and avoid fluid communication between the fluid inlet passage and the fluid outlet passage. 32. The heat exchanger according to claim 31, characterized in that the valve member responds to the fluid temperature in the outlet opening. 33. - The heat exchanger according to claim 32, characterized in that the valve member also responds to an excessive pressure differential between the inlet and outlet openings. 34. The heat exchanger according to claim 22, characterized in that it also comprises a bypass valve structure that is provided in the head, the bypass valve structure is operative to allow the fluid to derive the core structure when the fluid is below a predetermined temperature and to direct the flow of fluid through the core structure when the fluid is at or above a predetermined temperature. 35.- The heat exchanger according to claim 34, characterized in that the bypass valve structure is fixed in a removable manner to the head. 36.- The heat exchanger according to claim 35, characterized in that the bypass valve structure is also operative to allow the core structure to flow fluid, in response to a pressure differential between the inlet and outlet openings on a pressure default