MXPA96002822A - Method for installing a flector on a head in an ac exchanger - Google Patents

Abstract

The present invention relates to a method for installing a baffle in a tubular head for a heat exchanger, comprising the steps of: a) providing a baffle with a concave side surrounded by a periphery smaller than the internal periphery of the head; b) locate the baffle at a desired location within the head, and c) apply a compressive force to the baffle through the concave side to compress the baffle to a flat configuration.

Description

DEVIATION FOR HEAD IN A HEAT EXCHANGER FIELD OF THE INVENTION The present invention relates to heat exchangers, and more particularly to deviations used in heat exchangers. BACKGROUND OF THE INVENTION In recent years an explosion in popularity has been observed in the so-called "parallel loose" heat exchangers. a typical construction is illustrated in U.S. Pat. 4,688,311 issued August 25, 1987, issued to Saperstein, et. to the. Heat exchangers of this type have been used in a variety of applications including condensers and evaporators for air conditioners and cooling systems and in oil coolers, which are used to cool the lubricating oil or hydraulic fluid, particularly in automotive applications. There is indeed the suggestion in the prior art that parallel flow heat exchangers have still been employed as radiators to cool the engine coolant in the vehicles. Modern parallel type heat exchangers are typically made of aluminum and employ two separate tubular heads. Flattened tubes extended between the interiors of the heads and are in communication with them. The coil fins are located between the flattened tubes. Conventionally, aluminum is the selected material and the result is a compact lightweight heat exchanger, which operates with exceptional efficiency, particularly when the hydraulic diameter of the fluid passages inside the flattened tubes is 0.17 cm (0.70"). ) or less In many applications, it is desired that the fluid contained within the heat exchanger make more than one pass through the heat exchanger through the cooled air path in which the heat exchanger is disposed. It is conventional to locate one or more deviations in a head or both to achieve as many passes as desired.Deviations have typically been insertion elements similar to a plate that is disposed in the slots of the heads. as the point of contact of the deviation with the inside of the head, when the materials used are aluminum, you have confidence in the flow of a brass alloy to seal any of the holes. The use of slots in the heads can tend to weaken the heads and, in some cases, can result in a significant number of heads with cracks that are formed as a result of pressure in the fluid inside the heads, resulting from the application of heat in the exchanger during the process of welding with brass. In other cases, deviations similar to caps have been inserted in the inner end of the heads in the desired location, and then they are welded with brass in their place. While such deviations are usually completely free of cracks, this method of application does not by itself lead to use with a head whose inner cross section may vary. In the patent of the U.S.A. 4,615,385 issued October 7, 1986 to Saperstein, et al., Discloses a single head for heat exchangers of this type. To provide improved strength in the resulting exchanger, each head is in the form of a generally cylindrical tube with a series of slots in the tube formed on one side thereof. Between each slot of the tube, a dome is formed, the dome has a configuration of a composite curve. Due to the use of the domes between the adjacent grooves of the tube, the stresses in the tube in the joints of the head in the resulting exchangers are considerably reduced and a much stronger exchanger results. However, due to the use of domes, the cross section of the head is relatively large where each dome is formed and is relatively smaller where each groove is formed. Due, until now it has been impossible to provide such heads with deviations that are inserted in the internal end of the heads. The present invention is directed to overcome one or more of the above problems. BRIEF DESCRIPTION OF THE INVENTION It is a main object of the invention to provide a novel and improved method for providing a head with an internal deflection. More specifically, it is an object of the invention to provide a novel and improved method for installing a deviation in a tubular head. It is also an object of the invention to provide a heat exchanger that includes a head provided with a deflection according to the process or method of the invention. It is still another object of the invention to provide a novel deviation preform that can be used in practicing the method of the invention. An exemplary embodiment of the method of installing a deflection in a tubular head for heat intercalation includes the steps of: (a) providing a deviation with a concave lateral periphery smaller than the inner periphery of the head; (b) locating the deviation at a desired location within the head; (c) applying a compressive force to the deviation to compress the deviation to a planar configuration. As a result of the foregoing, the deflection expands peripherally within the head to engage with the interior of the head, where it can be secured and sealed, for example, not necessarily by brass welding. In one embodiment of the method, the deviation which is concave-convex has a generally circular periphery and includes a generally central convex dome surrounded by a peripheral skirt, directed radially outwardly. In a highly preferred embodiment of the invention, both the head and the deflection are made of aluminum and the deflection is welded with brass on both of its sides. In one embodiment of the invention, step (b) is carried out by placing the head on a mandrel, abutting against the stop and then placing the deflection inside the head in abutment with the mandrel. In one embodiment of the invention, step (c) is carried out by placing a second mandrel inside the head after step (b) and by moving the second mandrel against the deflection and in the direction of the so-called first mandrel. In one embodiment of the invention, step (b) is preceded by the step of dimensioning the interior of the head at the desired location of the deviation. Preferably, the step of dimensioning an expandable mandrel within the head in the desired location is performed and expanding the mandrel in the head in the desired location. In a highly preferred embodiment of the invention, the expandable mandrel is a slotted mandrel and the step of expanding the expandable mandrel is performed by moving a wedge inside the slotted mandrel. In one embodiment of the invention, a heat exchanger is provided which includes a head with a deflection and which is made according to the process described above. According to another facet of the invention, a diverting preform is provided for use in the manufacture of a heat exchanger with a tubular diverting head. The deflection preform comprises a metal dowel having a convex side and an opposite concave side. The dowel is circular and has a generally hemispherical dome with a diameter smaller than the dowel on one of its sides and a skirt directed radially outwards extended from the base of the dome towards the periphery of the dowel. Preferably, the skirt has a conical body. In a highly preferred embodiment, the lower skirt base is joined at the base of the dome and the skirt also extends axially away from the dome. Preferably, the dowels are formed of an aluminum foil and are coated with brass on both sides thereof. The invention also contemplates a method for making a heat exchanger head with an internal deflection, which comprises the steps of (a) providing a tubular head of a generally cylindrical configuration and having a series of slots that receive the tube in one of its sides that are separated by the domes configured as composite curves, the cross section of the head that is relatively larger in the domes and relatively smaller in the grooves of the tube; (b) providing a concave deviation of a generally circular periphery, and a sufficiently small diameter, so as to be received in the head and located therein in a transverse way to the head in the relatively small cross section; (c) locate the deviation within the head in one of the desired domes; (d) causing the deviation to be generally transverse to the head; and (e) collapsing the deviation to a generally flat configuration in one of the desired domes. Preferably, step (e) is effected by relatively moving the mandrels on opposite sides of the deflection in a mutual direction. Preferably, step (b) is effected by providing a deviation of a material similar to a sheet having a dome surrounded by a skirt generally directed radially outwards. In this embodiment, the dome is generally hemispherical and the skirt preferably is generally tapered. Other objects and advantages will become apparent with the following specification taken in conjunction with the accompanying drawings. DESCRIPTION OF THE DRAWINGS Figure 1 is a partially schematic view of a heat exchanger, specifically a condenser, made according to the invention, which may incorporate a head with an internal deflection made according to the invention; Figure 2 is an enlarged fragamentary section view of a head with a deflection installed therein and made according to the invention; Figure 3 is a side elevation of a biasing preform used in the invention; Figure 4 is a plan view of the deviation preform; Figure 5 is a block diagram of a method for manufacturing a heat exchanger, including a head with an internal deflection, according to the invention; Figure 6 is a fragmentary sectional view of an optional step performed with the method of the invention; Figure 7 is a view similar to Figure 6 but illustrating another step to carry out the invention; and Figure 8 illustrates the cross section of a mandrel used to perform the step illustrated in Figure 7. DESCRIPTION OF THE PREFERRED MODALITY An exemplary embodiment of the invention is illustrated in the drawings in connection with the heat exchanger which will be recognized as a condenser by those with experience in the art. However, it will be expressly understood that the applicability of the invention extends beyond the condensers and can be used in any type of heat exchangers employing tubular heads, including but not limited to, the evaporators and oil coolers. Referring now to Figure 1, a parallel flow condenser is observed with which the invention can be used, including the generally parallel spaced heads 10 and 12. The heads 10 and 12 are preferably made from a generally cylindrical tube. On its surface sides, a plurality of generally parallel slots or openings 14 are provided to receive the corresponding ends 16 and 18 of the flattened condenser tubes 20. The head tubes 10 and 12 are preferably welded, including a seam weld as shown in FIG. shows at 19 in connection with the head tube 12. The slots 14 are perforated on the surface sides of the heads 10 and 12. The slots 14 are naturally elongated and their direction of elongation is transverse to the direction of elongation of the heads 10. and 12.

Preferably between the slots 14, in the area shown at 22, each of the heads 10 and 12 is provided with a somewhat spherical dome to increase the pressure resistance as more fully described in U.S. Patent No. 4,615,385 commonly assigned, previously mentioned. The head 10 has a closed end by a cap 24 coated with brass or welded thereto. In the preferred embodiment of the invention, all the various components are formed of aluminum and all together are welded with brass and, consequently, in the usual case, of welding with brass by any of the means employed, the cap 24 is clamped. to the head 10. Similarly, the accessories, such as the accessory 26 is welded with brass with the other components and a tube 28 can be connected to the fitting 26 to define an outlet for the condenser. The lower end of the head 12 is closed by a cap 30, preferably welded with brass in place, similarly to the cap 24, while the upper end of the weld 12 is provided with a solder or coated brass in the place of the attachment 32. Typically, accessory 32 will serve as an entry through the direction of flow, which in some cases can be reversed.

A plurality of tubes 20 extended between the heads 10 and 12 are in fluid communication therewith. The tubes are geometrically parallel and also hydraulically parallel. Disposed between the adjacent tubes of the tubes 20 are the coil fins 34, although plate fins may be used, if desired. The upper and lower side channels 36 and 38 extend between the heads 10 and 12 to provide rigidity to the system. Each end of each of the channels 36 and 38 includes an outwardly turned flange 39, which is adapted to be attached to the adjacent head 10 or 12. As can be seen in Figure 1, each of the tubes 20 is a tube flattened and inside it includes an insert element or undulating separator of elongated construction. In cross-section, the insert element appears as completely as disclosed in US Pat. 4,688,311 previously identified. However, it will be understood that extruded tubes with multiple passages may also be used. Those skilled in the art will appreciate from the foregoing description that a one-step parallel flow heat exchanger has been described. However, as noted previously, in some cases, it is desirable that there may be multiple steps. In such a case, one or more deviations are placed in one of the tubes of the head or in the other of the tubes or in both tubes of the head 10 and 12. Turning now to Figure 2, the head 10 is illustrated, although it will be understood that what is illustrated is equally applicable to the head 12. More specifically, the grooves of the tube 20 are illustrated by receiving the ends 16 of the tubes 14. The domes 22 are illustrated between each of the flattened tubes 14 and it will be appreciated that in a parallel section taken in the direction of elongation of the head, the domes are curved. It will also be appreciated that because the heads 10 are generally cylindrical, the domes 22 will also have a curved appearance in cross section to the head 10, taken through either of the domes 22. Thus the domes 22 are formed of curves composite and as seen in Figure 2, is the result of a head having a relatively large cross section 42 in each of the domes 22 and a relatively small section 44 in each of the slots of the tube 20. It will also be appreciated that since the slots of the tube 20 and the domes 22 are located only on one side of each head, at least a part of the head will retain a cylindrical internal configuration greater than an arc length greater than 180 °. A deflection 46 is disposed within the head 10 at the desired location in the center of one of the desired domes 22, and is oriented in order to be transverse to the direction of elongation of the head 10. It is welded with brass in place during assembly in the heat exchanger. As illustrated in Figure 2, the deflection 46 is generally flat, although it will typically have a small shallow recess 48 on one of its sides and an area with a shallow, relatively large elevation 50 opposite the shallow recess 48. In many examples, adjacent the dome 22, the deflection 46 will have a slightly angular displacement as shown at 52. The deflection 46 is formed of a preform as illustrated in Figures 3 and 4. The preform is basically a circular dowel 60 which It has a hemispherical dome 62 on one of its sides. The base 64 of the dome 62 is joined to the minor base of a skirt with tapered body 66. The arrangement is such that the plug of the preform 60 is convex on its left side as illustrated in Figure 3 and concave on its right side , that is, it is concave-convex. The dowel 60 can be formed, taking a circular piece of an aluminum sheet-coated brass on both sides, and pressing it down into a ball bearing whose diameter is equal to that of the hemispherical dome 62 on its inner surface 68. The height of the dowel is designated by "H" as shown in Figure 3, while also in Figure 3 the diameter is shown as, D "In general, the ratio of" D "to" H " "It will be 2: 1 or greater.The following table illustrates the parameters that can be used when forming deviations to be used in standard aluminum tubes used as headers in heat exchangers.A material that can be used to make deviations is a brass sheet of No. 12 with a thickness of 0.15 cm (0.062") 3003-0, an aluminum sheet with metallic coating with a thickness of 4343 on both sides. All dimensions are given in inches unless otherwise indicated. Diameter Diameter of Head Height Diameter Dome Formation Deviation (D) Balls (H) 1. .688 .562 .250 .222 2. .875 .750 .312 .290 Diameter Diameter Size of Diameter Head Height Deviation Dome Formation (D) Balls (H) 3. 25 mm .875 .375 .318 4. 1.25 1.125 .500 .325 Turning now to Figure 5, the steps of the manufacturing method of a heat exchanger. As a first step is the formation of a head with domes and grooves in the tube, shown in block 70. This step increase makes heads 10 and 12 such as those disclosed in US Pat. 4,615,385 previously identified. After the head is formed, it is optionally placed on an expanded mandrel, as shown in block 71, and the expanded mandrel gives the size to the head as shown in block 72. The steps shown in block 71 and 72 are optional and depend on the ability to maintain the tolerances in blocks 71 and 72 in the formation of the head. The manner in which the step shown in block 71 and 72 is achieved is illustrated in Figure 6. As seen, a mandrel 80 is located on stop surface 82. A formed head such as head 10 is located on the mandrel 80. At its upper end, the mandrel 80 has a slot shown at 84 and is formed of a relatively elastic material. A generally circular ball 86 is formed in one leg 88 of the slotted mandrel, while a similar ball 90 is formed in the other leg 92 of the slotted mandrel 80. The balls are nominally the same radius as the internal diameter of the head 10, but when they are close together, they are sufficiently narrow one with respect to the others, so that they can quickly pass to the head in spite of the presence of the relatively small cross sections 44 (Figure 2). The length of the mandrel 80 in relation to the abutment surface 82 is such that the balls 86 and 90 will be placed at the central point of the selected dome 22., where the deviation is located eventually. A wedge-like element 94 moves from the opposite end of the head 10 between the legs 88 and 92 of the slotted mandrel 80 to urge the balls 86 and 90 to a coupling with the dome 22, and the opposite part of the wall of the head 10. The resulting size of the interior of the selected dome 22 is dependent on the degree of incursion in the mandrel of the wedge-like element 94 which, in turn, is selected to obtain the desired cross-sectional configuration in this location, the The cross-sectional configuration is uniformly produced from a head 10 at the next location as a result of the sizing operation. It will be appreciated naturally that if the tolerances can be maintained during the manufacture of the heads 10, there is no need for the preform of the steps shown in block 70 and 72 in Figure 5. In such case, the method can proceed directly as a block 100, which represents the step of placing the head 10 in a mandrel or fixed shaft 102 against the stop surface 103. As shown in Figure 7, the fixed mandrel 102 has an upper surface 104 that is located 0.031"(half the thickness of the sheet from which the preform 60 is made) below the midpoint of the selected dome 22 in relationship with the stop surface 103. This distance is selected for an aluminum sheet with a thickness of 0.062", which is used to make the preform 60 as previously mentioned. The preform 60 can be inserted laterally inside the head and in turn be transverse with the direction of elongation of the head 10, resting on the upper surface 104 with the dome in the uppermost part. This step is shown in block 102 in Figure 6, and the resulting orientation of the components is evident in Figure 7. The deflection is then expanded by compressing it to a planar configuration. That is, the preform 60 is collapsed and this is achieved through the application of a compressive force by moving an axis or mandrel 110, which moves downwardly within the head 10 in a coupling with the dome 22. Once this step is completed, the preform 60 will appear as the deviation 46 shown in Figure 2. To facilitate the compressive process, the shafts or mandrels 102, 110 are generally cylindrical, having a configuration that is closely close to the internal peripheral configuration of the head 10 and 12. It is also provided with a flat surface 112 (Figure 8) on one of its surfaces, in order to allow a space in the relatively small cross sections adjacent to the slots of the tube 20. The step of expanding the Deviation is shown in Figure 5, in block 114 and after performing the step, the head 10 is removed from the mandrel as shown in block 116. The head 10 is then moved to a Detection station where the determination is made as to whether or not the deviation is in fact in place. This is shown in block 118 and can be as simple as placing a light source at one end of head 10 and a photosensitive device at the opposite end. Assuming the presence of a deviation has been detected in the step represented by block 118, an identification mark is placed on the head as shown in step 120, to facilitate subsequent inspection. After marking the head, a brass solder flux, such as a potassium fluoaluminate flux used in the brass welding process called Nocolok ™, is introduced into the deflection side 46 that was originally the side of the dome. This is shown in block 122. The components are then assembled to the configuration generally illustrated in Figure 1 and held in place by a suitable fastener as is well known. This is represented by block 124. The clamping element is then placed in the brass welding furnace and the components are jointly subjected to brass welding as shown by a block 126. The resulting assembly can be tested, packed and shipped. From the foregoing, it will be appreciated that the method of the present invention does not comprise weakening the heads when grooving and does not depart from the cost of such forming operation. Cracks associated with the deviations introduced through the slots are avoided and a relatively better seal, obtained through the insertion at the ends of the deviations, can be achieved, notwithstanding the fact that the heads in a preferred embodiment are type that have domes located between the grooves of the tube and, and therefore, have an irregular interior. Naturally, the method can be used if desired with heads that have perfectly cylindrical interiors, that is, without the domes.

Claims (19)

1. NOVELTY OF THE INVENTION Having described the invention as above it is considered of our property that contained in the following: CLAIMS 1. A method for installing a deviation in a tubular head for a heat exchanger comprising the steps of: a) providing a deviation with a concave side, and a periphery smaller than the internal periphery of the head; b) locate the deviation in a desired location within the head; and c) applying a compressive force to the deflection to compress the deflection into a planar configuration. The method of claim 1, wherein the deviation is concave-convex and generally has a circular periphery and includes a generally convex central dome, surrounded by a peripheral skirt directed radially outwardly. 3. The method of claim 1, wherein both the head and the deflection are made of aluminum and the deflection is coated with brass on both sides. The method of claim 1, wherein step b) is carried out by placing the head on an axis, abutting against a stop, and then placing the deviation within the head in abutment with the axis or mandrel. The method of claim 1, wherein step c) is carried out by placing a second axis or mandrel inside the head after performing step b) and moving the second mandrel against the deviation in the direction of the so-called first mandrel or axis. The method of claim 1, wherein step b) is preceded by the step of sizing the interior of the head to the desired location. The method of claim 6, wherein the sizing step is performed by locating an expandable mandrel within the head in the desired location and expanding the mandrel within the head in the desired location. The method of claim 7, wherein the expandable mandrel is a slotted mandrel, and the step of expanding the expandable mandrel is effected by moving a wedge inside the slotted mandrel. 9. A heat exchanger including a head with a deflection therein, made by the process of claim 1. 10. A diverting preform for use in the manufacture of a heat exchanger with a diverted tubular head and comprising : a metal dowel having a convex side and an opposite concave side, the dowel is circular and has a generally hemispherical dome of a diameter smaller than the dowel on one of its sides, and a skirt directed radially outwards extended from the base of the dome towards the periphery of the plug. 11. The diverting preform of claim 10, wherein said skirt is generally tapered. 12. The diverting preform of claim 11, wherein the minor skirt base joins the base of said dome and the skirt also extends axially away from said dome. 13. The diverting preform of claim 12, wherein said dowel is formed of an aluminum foil and is coated with brass on both of its sides. A method for manufacturing a head of a heat exchanger with an internal deflection comprising the steps of: a) providing a tubular head of a generally cylindrical configuration having a series of slots that receive the tubes on one of their sides , which are separated by domes configured as composite curves, the cross section of the head is relatively larger in said domes and relatively smaller in the slots of the tubes; b) providing a concavo-convex offset of a generally circular periphery, and a diameter small enough to be received in the head, located generally transverse thereto in a relatively large section, greater than the relatively small cross section; c) locating the deviation within the head in one of said desired domes; d) make the deviation is generally transverse to the head; and e) collapsing the deviation to a generally flat configuration in one of the desired domes. The method of claim 14, wherein step e) is effected by relatively moving the mandrels mutually on opposite sides of the deflection. 16. The method of claim 14, wherein step b) is effected by providing a deflection of a material similar to a sheet having a dome generally surrounded by a skirt generally axially directed outwardly. 17. The method of claim 16, wherein the dome is generally hemispherical. 18. The method of claim 16, wherein said skirt is generally tapered. 19. A method for installing a deflection in a circular head for a heat exchanger comprising the steps of: a) providing a deviation with a convex side and a periphery smaller than the internal periphery of the head; b) locate the deviation in a desired location with the spindle; and c) applying a compressive force to the deflection to compress the deflection into a planar configuration.