WO2012052465A1 - Heat exchanger manifold end tank - Google Patents

Abstract

The present invention relates to a heat exchanger manifold end tank comprising side walls defining a flow-through chamber and substantially made from a moulded polymeric material, the end tank being reinforced with a strengthening element consisting of a metallic sheet, extending in between two opposite side walls and comprising parts integrally moulded in the two opposite side walls.

Description

HEAT EXCHANGER MANIFOLD END TANK

The present invention relates to a heat exchanger manifold end tank, in particular a reinforced heat exchanger manifold end tank. The invention further relates to an end tank assembled in a heat exchanger, in particular assembled in an automotive charge-air-cooler. The invention also relates to a process for manufacturing the end tank and to the use of the end tank in a gas- or liquid-circulating system such as for example a heat exchanger, a charge-air cooler, an automotive charge-air cooler, an air-conditioner.

Heat exchangers transfer heat energy from one liquid (or gas) to another liquid (or gas), or from a liquid to a gas, or vice versa, without mixing the two. Radiators, automotive radiators and automotive charge-air-coolers are common examples. Heat exchangers of the type which are employed in automobiles, for example, as charge air coolers for turbochargers, comprise a manifold in the form of a separate tank and header parts which are joined together to define a manifold housing. This housing is connected to a large number of bundled heat exchange tubes through which air to be cooled is passed. The heat exchange tubes are connected at end portions thereof to the header part. The heat exchange tubes, or heat transfer tubes, are also known as cooling pipes or cooling channels. As further heat transfer elements automotive heat exchangers generally comprise fins or corrugated plates, generally made of metal. The tubes and cooling elements are generally stacked together into a larger package and welded or brazed together with the plate comprising the holes, to form a single or unitary heat exchange core. Heat exchange cores are also known under the name of cooler body and are generally made of a lightweight heat conductive metal, such as aluminium.

Such heat exchangers typically have two confronting end tanks, which are also referred to as end caps or manifold bodies, the first tank also being known or referred to as inlet end tank, inlet end cap, inlet manifold, or introduction tank, whereas the other tank also being known or referred to as outlet end tank, outlet end cap, outlet manifold, or discharge tank. With an inlet end tank is understood a conduit like device used to channel the medium to be cooled into the tubes. With an outlet end tank is understood a conduit like device used to channel the medium after being cooled out of the tubes. The end portions of the heat exchange tubes, through which tubes air or other medium (generally water or a water/glycol mixture) to be cooled is passed, are received by the aperture in the end tank and extend into the end tank.

The functioning of such heat exchangers is illustrated with the example of an automotive radiator. Heat from the hot engine water is pumped through the radiator pipes, while air is blown through the radiator fins. The heat energy produced by the engine is transferred via the cooling water to the air, thus keeping the water at the right temperature, to keep the engine from overheating. Essentially automotive radiators are liquid-to-air heat exchangers. Automotive heat exchangers comprise end tanks having an open face delimited by the header part of the heat exchanger core.

Heat exchangers of the type described include, for example as disclosed in Japanese Utility Model Laid-open Publication No. 58-158985, two confronting tanks connected together by a plurality of parallel spaced tubes each having a multiplicity of radial fins. A heat exchange medium led into one of the tanks through an inlet formed therein is circulated through the tubes via the other tank and then discharged from an outlet formed in the one tank. During circulation, the heat exchange medium is subjected to heat-exchange with air passing around the fins so that air is heated by taking up heat from the heat exchange medium.

Such heat exchangers are also known from US patent US-5,351 ,751.

This patent describes heat exchangers of the type, which are employed in automobiles, for example, as charge air coolers for turbochargers. The known heat exchanger from US-5,351 ,751 comprises a manifold body in the form of separate tanks, indicated in US-5,351 ,751 with the name manifold, and a heat exchange core. The manifold body in US-5,351 ,751 can be made of metal, preferably aluminium, and can be joined to the header part, for example by welding. According to US-5,351 ,751 , it is also possible to apply manifold bodies formed of plastic. The heat exchanger tank of US-5,351 ,751 comprises an elongate trough-shaped body having opposite side reinforced with a tie bar.

A problem with heat exchangers as described above is that the end tanks are subject to expansions arising from elevated temperatures and pressures, which render them liable to failure. Conventionally, the tank parts are reinforced to resist this expansion by the provision of increased wall thickness, the addition of internal and/or external ribbing, or the addition of internal tie bars which extend between inner walls of the tank, and which are cast with the tank or are welded in position. An increase in the header material gauge may also be employed as a means of reinforcement.

A problem directly related to the expansions of the end tanks due to variations in the pressure is that the aluminium core to which the end tanks are fastened can get damaged. Rigidity and stiffness of the end tank are important to prevent vibrations and expansions in the end tank and damage of the aluminium heater core. That is the reason that different means of strengthening have been proposed, but none has been very successful or completely satisfying.

There are a number of problems with these means of strengthening. The addition of extra material for strengthening adds weight and increases the cost of the tank. Internal ribs made from the same material as the end tank in a one step moulding step generally have a flow line that will be a weak spot and particular prone to effects of degradation under the influence of the heat of the cooling medium. It also complicates the tooling, patterns, moulds etc which are required. Internal ribs disturb the flow of the cooling medium. Where internal tie bars are welded into position within the tank there is a risk of catastrophic failure should a weld joint fail or a tie bar become dislodged. Where the tie bars are cast in position, this complicates the manufacture, and may require secondary operations to complete the casting, or the use of more than one sand core. Such casting procedures also require additional cleansing in order to remove residue created during this additional casting.

In French Patent Application, published No. 2614980 it has been proposed to provide in a plastics tank a transverse generally U-shaped strengthening wire which is fitted across the tank housing, legs of which are received in bores moulded into opposite sides of the tank. It is, however, particularly difficult to locate the wires in the bores since the ends of the wires must be aligned exactly with the bores before they can be received therein. Also, although these provide a strengthening function in a plastics tank, such wires would be quite inadequate for strengthening a cast metal tank for use as a charge air cooler tank.

The heat exchanger tank of US-5,351 ,751 comprises an elongate trough-shaped body having opposite side walls reinforced with a tie bar extending between opposite side walls; said tie bar comprising an elongate body having enlarged head portions at opposite ends thereof which are of generally wedge-shaped section of dimension which decreases in a direction generally perpendicular to the elongate extent of the body of the tie bar, and said tank side walls defining opposite pockets for receiving therein respective head portions of the tie bar. The aim of the invention is to provide a solution for the reinforcement of heat exchanger manifold end tanks that does not have the above problems, or at least so in reduced extent.

This aim has been achieved with the heat exchanger manifold end tank according to the invention comprising side walls defining a flow-through chamber and substantially made from a moulded polymeric material, the end tank being reinforced with a strengthening element consisting of a metallic sheet, extending in between two opposite side walls, and comprising parts integrally moulded in the two opposite side walls.

The effect of the use of a metal sheet is that it can easily be integrated in the end tank during the moulding process for making end tank without the need modification of the basic shape of the end tank, expensive tooling, or additional casting, cleansing or assembly steps. The metal sheet is thin enough to limit disturbing the flow of the cooling medium inside the flow through chamber, meanwhile

contributing significantly to the strength of the end tank. It does not suffer from weak spot of weld lines and deterioration thereof as moulded internal ribs. The solution can simply be applied in existing end tank designs, without the need of extensive design modifications, additional assembly steps or tooling. The invention also contributes significantly to the stiffness of the end tank, thereby reducing the likelihood of damage of the aluminium core of the heat exchanger.

Due to the unique and innovative design of the end tank of the present invention, the heat exchanger surprisingly maintains its performance at a good level for longer time periods. Additional advantages of the end tank of the invention can also be enhanced mechanical stability and structural robustness.

Unless the context clearly indicates otherwise, as used herein plural forms of the terms herein (for example protrusion, undercut) are to be construed as including the singular form and vice versa.

By 'sheet' is meant herein a material's configuration that it is relative thin to its length and width. The sheet can have different shapes, suitably though it is planar, or essentially planar but folded configuration. The sheet may have a rectangular basic configuration, but does not necessarily need to be so. "Basic" means here prior to folding.

With the strengthening element extending in between two opposite side walls is meant herein that said strengthening element is positioned inside the end- tank, at least a central part of it. As a matter of fact, this excludes the parts being moulded into the two opposite side walls. Suitably, the strengthening element comprises a central part freely bridging the two opposite side walls.

By 'moulded' is meant herein that an object is made in a mould. In the context of the present invention, a mould is a shaped cavity used to give a definite form to a polymeric material.

By "integrally moulded' as in 'metallic sheet (being) integrally moulded in the two opposite side walls' is meant herein that the metallic sheet is integrated in a larger body by a moulding process, to form an undivided, inseparable part of the body. In this particular case, the body is the end tank.

In this respect it is noted that with the term "substantially" in 'the end tank (being) substantially made from a moulded polymeric material' is meant that the larger part of the end-tank is made from a moulded polymeric material', but that small parts thereof can be made from another material, such as the strengthening element being made from a metallic material.

By 'metallic' in metallic sheet is meant herein substantially consisting of elemental metal and/or of a metal alloy. Suitable metals include iron, aluminium and cupper. Suitable alloys include steel. Preferably a corrosion resistant metal such as corrosion resistant steel is used.

"Substantially consisting of" as used herein means that the elemental metal or alloy is present in a given object i.e. metallic sheet, in an amount greater than or equal to about 95 % w/w, preferably greater than or equal to about 96 % w/w, even more preferably greater than or equal to about 97 % w/w, most preferably greater than or equal to about 98 % w/w, even most preferably greater than or equal to about 99 % w/w, for example greater than or equal to about 99.1 % w/w, for example greater than or equal to about 99.5 % w/w, for example greater than or equal to about 99.7 % w/w, for example greater than or equal to about 99.8 % w/w, for example greater than or equal to about 99.9 % w/w, for example the elemental metal or metal alloy accounts for 100 % w/w of the total amount of given object

In the context of the present invention, an alloy is a solid

homogeneous mixture of two or more elements, at least one of which is a metal that itself has metallic properties. Suitably, the alloy is a solid homogeneous mixture of two or more elements. Exemplary alloys are, but not limited to, brass (is an alloy made from copper and zinc) and bronze (is an alloy of tin and copper), steel (is an alloy of carbon and iron), duralumin (aluminium and copper). Preferably, the alloy is steel or bronze or duralumin, most preferably the alloy is steel. The metal sheet used for the strengthening element in the present invention suitably has a thickness of 3 mm or less. Preferably the thickness is in the range of 0.5 - 2 mm. A metal sheet with a thickness of more than 3 mm might be used; however, this would require thicker walls parts to embed the end of the metal sheet. If the metal sheet would be much thicker it would also be hard to fold or bend to provide it with protrusions, as described further below. The metal sheet can be thinner than 0.5 mm, for example 0.3 mm, however if it would be much thinner, it would hardly contribute anymore to the stiffness of the end tank.

A thickness around 1 mm is a good optimum in both increasing stiffness of the tank, good foldability, good integration in the side walls of the end tank, and limited flow resistance for the hot medium flowing through the end tank.

In the context of the present invention, with "polymeric material" is meant a thermoplastic composition or a cured thermosetting composition. With

'thermoplastic composition' is meant herein a composition comprising at least a thermoplastic polymer. With the term 'thermosetting composition' is meant herein a mixture of components that may form a liquid or a solid a powder-like material which mixture is liquid at room temperature and which mixture has the ability to form an irreversibly crosslinked network (the so-called 'cured thermosetting composition" or "thermoset material").

Both the thermoplastic composition and the thermoset material can comprise various additives, next to the polymeric components. Additives that can form part of the polymeric material include additives commonly known to the skilled person such as lubricants, nucleating agents, stabilizers, impact modifiers, flame retardants, impact modifiers, fillers, plasticizers, reinforcement agents such as glass fibers, inorganic fibers, nanofillers, etc.

For clarity, in the context of the present invention, the metallic sheet, since being integrally moulded in the two opposite side walls, forms an undivided, inseparable unit with the end tank, thus being part of the end tank without the use of any glue and/or screws and/or welds, and/or joints, or alike. For the metallic sheet to becoming such an inseparable part of the body in the way described above, it is clear that end parts of the metallic sheet have to be embedded in the side walls, more particular embedded in the moulded polymeric material constituting the side walls. This is achieved by a moulding process, wherein a polymeric composition is injected into a mould such that the polymeric composition envelops parts of the metallic sheet. Next to end parts embedded in the moulded polymeric material, the metallic sheet will have a central part, positioned between the opposite side walls. This central part is preferably planar. Also preferably the central part is barren, i.e. not covered with polymeric material. The central part may be covered by polymeric material, but this would not contribute in significant extent to the stiffness of the end tank. A polymeric layer on the central part will also more easily deteriorate under the influence of the hot medium in the heat exchanger flowing through the end tank. The central part of the strengthening element is subjected to the hot medium at both sides. This in contrast to the side walls of the end tank, which are so exposed only at one side (the inside), while the other side (the outside) will remain relatively cool. The metallic strengthening element according to the invention is not only very simple in the way it is integrated in the end tank, but also very effective in terms of strengthening the end tank as well as in retaining the increased stiffness under exposure to the hot medium.

Suitably, the end tank according to the invention has an elongated through-shaped body with a spout wherein, wherein the metal sheet is positioned closely to the spout. The metal sheet shall be positioned such that the flow of the medium is not seriously hindered, and the planar part shall not be perpendicular to the flow direction. Preferably the planar part is parallel, or essentially so, to the main flow direction of the cooling medium flowing through the end tank. As a result thereof the end tank of the present invention is a durable stiff construction with a reduced noise level. The reduced level of noise generated by the end tank is manifested in that the heat exchanger surprisingly maintains its performance at a good level and for longer time periods in operation.

Preferably, the metallic sheet in the end tank according to the invention comprises protrusions being integral to the metallic sheet.

By 'integral to' is meant herein constituting an undiminished entirety. For clarity, the term 'integral to' does not include gluing, screwing, welding or other means of integrating an object onto another object. For example, in the context of the present invention, the protrusions are integral to the metallic sheet is to mean that the protrusions are undivided, inseparable from the metallic sheet, being a constituent of the metallic sheet without the use of any glue and/or screws and/or welds.

In a preferred embodiment of end tank according to the invention, the metallic sheet comprises at least two protrusions, one of which is embedded in one of the two opposite side walls and the other protrusion is embedded in the other of the two opposite side walls. A 'protrusion' is an extension above or below a plane. In case of this metallic sheet, a protrusion is meant herein to be an integral part of the metallic sheet, extending above or below the central part of the metallic sheet. The denomination which side is above and which side is below is arbitrary.

More preferably, the metallic sheet comprises at least four protrusions, two of the four protrusions are embedded in one of the two opposite side walls and the other two of the at least four protrusions are embedded in the other of the two opposite side walls. More particularly, the at least two protrusions embedded in one and the same side walls are pointing to opposite directions. Suitably, the metallic sheet comprises multiple protrusions embedded in one and the same side wall, wherein adjacent protrusions are pointing to opposite directions. Also suitably, alternating and non-adjacent protrusions are pointing to the same direction.

By 'adjacent' is meant herein a position that is linked to another position by an edge.

By 'non-adjacent' is meant herein is meant herein a position that is not linked to another position by an edge.

By 'direction' is meant herein the direction in which the protrusions extend away from the central part, i.e. either above or below the central part of the metallic sheet.

The advantage of such metal sheet, comprising one or more protrusions embedded in the side walls, is that the end tank is even more robust and the metallic sheet contributes even better to the mechanical strength of the end tank. With protrusions pointing at opposite directions, the mechanical properties are even further improved.

The metallic sheet can be provided with protrusions, simply by bending an end part, such that that end part extends above or below the plane of the central part. Multiple protrusions can be provided for example by making cuts in the end parts of the metallic sheet and bending adjacent pieces of metallic sheet, separated from each other by said cuts, in opposite directions.

In a special embodiment, the protrusions comprise undercuts.

Suitably, the undercuts consist of holes and/or corrugations and/or lips.

By 'undercut' is meant herein an underside recess either cut-out or moulded into an object so as to leave a topside lip or protuberance. In case of the metallic sheet the undercuts are suitably made by cut-out holes or cut-out lips. The lips can also be used in the production process to position the metallic sheet in the cavity of a meld.

The advantage of the presence of said undercuts in the protrusions is that the metallic sheet is even more firmly fixed in the opposite side walls.

Suitably, the metal sheet has a closed structure, but alternatively it may be perforated as well. By 'perforated' is meant herein pierced with one hole or a plurality of holes.

The end tank according to the invention, as well as any modification or embodiment thereof as described hereabove, is suitably assembled in a heat exchanger. The heat exchanger preferably is an automotive charge-air-cooler.

The present invention also relates to a process for making a heat exchanger manifold end tank. The process comprising the steps of:

o providing a mould with a cavity;

o providing a metallic sheet;

o positioning the metallic sheet in the mould in a way that parts of the sheet are positioned inside the cavity;

o injecting a polymeric composition into the mould so that the polymeric

composition envelops the parts of the metallic sheet that were positioned in the cavity, thereby forming the end tank;

o removing the moulded end tank out from the mould.

In a preferred embodiment of the process according to the invention, the metallic sheet comprises protrusions and at least one protrusion is used to position the metallic sheet in the mould in a way that at least the protrusions are to be enveloped by the polymeric composition.

The present invention also relates to use of the reinforced heat exchanger manifold end tank as defined above or obtained by the process described above in a gas- or liquid-circulating system.

By 'gas- or liquid-circulating system' is meant herein a stand alone equipment or a part of a device that can circulate a gas or a liquid, such as for example a heat exchanger, a charge-air cooler, an automotive charge-air cooler, an air- conditioner.

Fig. 1. Schematic drawing of a metallic sheet for use in the end tank according to the invention.

Figure 1 shows a schematic drawing of an embodiment of a metallic sheet (1) for use in the end tank according to the invention. The metallic sheet comprises a central planar part (14) and various protrusions (2, 4, 6, 8, 10, 12). 2 and 4 constitute adjacent protrusions pointing into opposite directions. The same holds for protrusions 8 and 10: 8 extends in one direction at one side of the central planar part (14), while 10 extends in opposite direction at the other side of the central planar part (14). Protrusion 12 comprises several small undercuts. The metal sheet with the protrusions of figure 1 has been made from a single metal sheet by folding pieces of the metal sheet along lines (16) and (18). The metallic sheet of Figure 1 can be integrally moulded in opposite side walls of a heat exchanger manifold end tank, by overmoulding end parts of the metallic sheet comprising the protrusions during the production process of the end tank with a polymeric moulding material. The so integrally moulded metallic sheet becomes a strengthening element for the end tank.

Claims

A heat exchanger manifold end tank comprising side walls defining a flow- through chamber and substantially made from a moulded polymeric material, the end tank being reinforced with a strengthening element consisting of a metallic sheet, extending in between two opposite side walls and comprising parts integrally moulded in the two opposite side walls.

An end tank according to claim 1 , wherein the metallic sheet comprises protrusions being integral to the metallic sheet.

An end tank according to claim 1 or 2, wherein the metallic sheet comprises at least two protrusions, one of which is embedded in one of the two opposite side walls and the other protrusion is embedded in the other of the two opposite side walls.

An end tank according to claim 3, wherein the metallic sheet comprises at least four protrusions, two of the four protrusions are embedded in one of the two opposite side walls and the other two of the at least four protrusions are embedded in the other of the two opposite side walls, and wherein at least two protrusions embedded in one and the same side walls are pointing to opposite directions.

An end tank according to any one of claim or 3 or 4, wherein the protrusions comprise undercuts.

An end tank according to any one of claims 1-8, wherein the end tank is assembled in a heat exchanger, preferably being an automotive charge-air- cooler.

A process for making a moulded heat exchanger manifold end tank as defined in any one of claims 1-6, comprising the steps of:

o providing a mould with a cavity;

o providing a metallic sheet;

o positioning the metallic sheet in the mould in a way that parts of the sheet are positioned in the cavity;

o injecting a polymeric composition into the mould such that the polymeric composition envelops the parts of the metallic sheet that were positioned in the cavity, thereby forming the end tank;

o removing the moulded end tank out from the mould. A process according to claim 7, wherein the metallic sheet comprises protrusions and at least one protrusion is used to position the metallic sheet in the mould in a way that at least the protrusions are to be enveloped by the polymeric composition.

Use of the reinforced heat exchanger manifold end tank as defined in any one of claims 1-6 or obtained by the process according to claim 7 or 8 in a gas- or liquid-circulating system.