Patent Application
20100175863
The invention relates to a heat-exchange insert for a heat-exchange device and to heat-exchange devices comprising such inserts.
It relates more particularly to a heat-exchange device, notably for motor vehicles, comprising a core of tubes spaced by a gap and a plurality of corrugated heat-exchange inserts in the form of metal strips folded so as to form a succession of substantially flat portions each placed between two tubes and connected in twos by a bent joining portion with a dimension suited to the gaps.
The function of a heat-exchange device is to allow the exchange of heat between a fluid circulating inside tubes and an external fluid passing through the heat-exchange device. To increase the performance of heat exchange between the fluid circulating inside the tubes and the external fluid, it is a common practice to provide the heat-exchange device with means making it possible to increase the surface area of exchange between the external fluid and the fluid circulating inside the tubes.
Accordingly, such a heat exchanger commonly comprises one or more rows of aligned tubes in which a coolant fluid circulates. The assembly of these tubes is usually called the core. The function of such a heat exchanger is to allow an exchange of heat between the coolant fluid circulating in the tubes and a fluid passing outside the heat-exchange device.
Therefore, it is known practice to provide the heat-exchange device with a plurality of heat-exchange inserts with a generally corrugated appearance formed by the succession of substantially flat portions connected in twos by a bent joining portion. Usually, a corrugated insert is placed between two tubes so that a part of the bent portion is in contact with a tube.
Such a heat-exchange device may, for example, be incorporated into an air conditioning system of a motor vehicle. In this case, the external fluid passing through the device is usually air intended to be blown into the interior of the vehicle, and the coolant fluid a refrigerant fluid. The heat exchange, in this case, is intended to cool the blown air. The heat-exchange device is then an evaporator.
The circulation of the fluid inside the air conditioning circuit is provided by a compressor, usually driven directly by the engine of the motor vehicle.
Currently, a weight reduction in the components incorporated into vehicles is being sought. Notably, the heat-exchange device is made of metals, in particular of aluminum. In order to comply with current requirements, it has been deemed necessary to reduce the thicknesses of the metal sheets used for producing such heat-exchange devices.
The thickness of the metal sheets used tends to be less than 70 micrometers for the inserts and less than 270 micrometers for the tubes. Such thickness reductions result in disadvantages such that the mechanical strength of the heat-exchange device is reduced causing an increased risk of failure and of accelerated deterioration.
The risk of deterioration is all the greater when, in the production phase of the heat-exchange device, the core of tubes and of inserts is placed under retention stress in order to ensure a good cohesion during the final manufacturing phase consisting in bracing the various elements together.
Under such retention forces, the core of tubes and of inserts may be deformed and/or shifted and therefore be defective, for example by the creation of leaks, or be less efficient, for example by an increase in pressure loss.
The object of the invention is therefore to propose a new type of heat-exchange device of the type mentioned in the introduction that overcomes the aforementioned drawbacks.
The invention therefore provides for an insert for a heat-exchange device made from a metal strip or metal sheet. The insert comprises at least a first zone having a first thickness and at least a second zone having a second thickness.
The first thickness and the second thickness are such that the second thickness is less than or equal to two times the first thickness and the second thickness is greater than or equal to one and a half times the first thickness.
In a preferred embodiment of the invention, the second zone defines a localized extra thickness obtained by folding the metal strip over a first length, in a preferred manner arranged at the ends of the insert.
In a particularly advantageous manner, the localized extra thickness is thinned, notably by rolling.
Alternatively or additionally, the first zone is obtained by locally thinning the metal strip, achieved by machining, by rolling, by stamping or by forming.
Advantageously, the localized extra thickness of the insert defines at least one transverse excrescence of a given height, for example equal to the difference between the second thickness and the first thickness.
The present invention is also specific to a heat-exchange device comprising at least one insert as defined above.
In a preferred embodiment of the invention, the insert comprises two localized extra thicknesses arranged on one and the same side or on two opposite sides of the insert.
Preferably, the exchanger comprises at least one heat-exchange tube arranged between at least two localized extra thicknesses.
As a variant, the heat-exchange tube comprises at least one localized deformation capable of interacting with the localized extra thickness of the insert.
Other features and advantages of the invention will appear on examination of the following detailed description and of the appended drawings which may serve to supplement the understanding of the present invention, but also, as appropriate, to contribute to its definition in which:
The corrugated inserts 10 take the form of a metal sheet or strip 20 folded so as to form a succession of flat or substantially flat portions 22 each placed between two tubes 8 and connected in twos by a bent joining portion 24 with a dimension suitable for the gaps 12 arranged between two successive tubes 10.
The heat-exchange device 2 also comprises a first collector ring 4 and a second collector ring 6 respectively receiving one and the other of the ends of fluid-circulation tubes 8, notably a refrigerant or coolant fluid. The tubes 8 are placed in line, evenly spaced from one another, and thus form the core of tubes 8.
The first collector ring 4 is connected to an inlet manifold 14 and the second collector ring 6 is connected to an outlet manifold 16 connected respectively to an air conditioning circuit in which a fluid, notably a refrigerant or coolant fluid, circulates.
Therefore, the fluid, originating from an upstream portion of the air conditioning circuit, enters, via the inlet manifold 14, the first tubular collector ring 4, circulates in the tubes 8 and reaches the second collector ring 6. From there, the fluid travels through the second collector ring 6 before leaving via the outlet manifold 16, which is connected to a downstream portion of the air conditioning circuit.
According to an alternative embodiment, the heat-exchange device 2 comprises a single collector ring having two internal portions separated by an internal partition or produced by two collector chambers placed side by side so that the inlet manifold 14 and the outlet manifold 16 are respectively placed in the single collector ring.
The core of tubes 8 and of inserts 10 comprises two end plates 18 contributing to the general holding and overall strength of the heat-exchange device 2.
The present invention also covers heat-exchange devices that do not comprise end plates 18.
The heat-exchange device 2 makes it possible to achieve an exchange of heat between an external fluid, for example air, passing through the heat-exchange device 2 and the fluid circulating inside the tubes 8, for example a refrigerant or coolant fluid.
In the example of
As shown in
Each insert 10 is made in the form of a folded metallic metal sheet or strip, for example made of aluminum alloy. Each insert 10 is provided with louvers 26 made by cutting into the metal strip 20.
The corrugated insert 10 is made, for example, by successive folds of the metal strip sometimes called a “flat band”. The insert 10 has a succession of flat portions 20 arranged so that two adjacent flat portions 20 are connected together by a joining portion 24.
The heat-exchange device 2 is traversed by an airflow F. The result of this is therefore that the airflow F travels over the core of tubes 8 and of inserts 10.
The heat-exchange device 2 therefore has an upstream face forming the face by which the airflow F enters the heat-exchange device 2 and a downstream face forming the face at which the airflow F leaves the heat-exchange device 2.
According to the present invention, the insert 10 also comprises a localized extra thickness 30. This localized extra thickness 30 makes it possible to increase the rigidity of the insert 10 and therefore to contribute to the increased strength of the heat-exchange device 2.
Preferably, two localized extra thicknesses 30 are arranged at the two ends of the insert 10 in the direction of flow of the airflow F. Therefore, the first localized extra thickness 30 is placed at the upstream face of the heat-exchange device 2 and the second localized extra thickness 30 is placed at the downstream face of the heat-exchange device 2.
According to a first exemplary embodiment, the localized extra thickness 30 is made by localized turning, notably by folding, over a first length A of the metal strip 20 forming the insert 10. Therefore, if the metal strip has a first thickness Th1, the localized extra thickness 30 has a second thickness Th2, such that the second thickness Th2 is equal to twice the first thickness Th1.
The insert 10 is therefore such that it comprises a first zone having the first thickness Th1 and at least a second zone having the second thickness Th2.
Such an embodiment makes it possible to have a first thickness Th1 less than or equal to twice the second thickness Th2.
Moreover, it is, for example, possible to locally thin the metal strip 20, for example by rolling, in order to define a first zone of thickness Th1 and a second zone of thickness Th2, such that the first thickness Th1 is less than the second thickness Th2.
Notably, the localized extra thickness 30 is thinned, for example by rolling, in order to reduce the dimension of the localized extra thickness 30 and obtain the second thickness Th2.
According to this embodiment, it is desirable that the second thickness Th2 is between one and a half times and twice the first thickness Th1.
Moreover, the present invention makes it possible for the localized extra thicknesses 30 to define end abutments having a height h2 at least equal to the difference between the second thickness Th2 and the first thickness Th1.
Such end abutments also help to hold the inserts 10 in position between the tubes 8. Specifically, as shown notably in
Alternatively, according to a second embodiment, not shown, it is possible to obtain the localized extra thickness 30 by thinning a first portion of the insert 10, in particular by machining operations. Preferably, the first portion of the insert 10 which is thinned is located symmetrically relative to the midplane of the core of tubes 8 and of inserts 10. The midplane is a plane equidistant from the upstream and downstream faces of the heat-exchange device 2 and parallel to the latter.
Such a retention is illustrated in greater detail in
As shown in
Thus held, the inserts 10 are placed in position and held so that they cannot move between the tubes 8 when placed under pressure for the assembly of the heat-exchange device 2.
According to the example of
According to this example, the insert 10 is held in position on the tube 8.
According to another variant embodiment, it can be envisaged that the two localized extra thicknesses 30 are placed on either side of the insert 10. This is more particularly shown in detail in
As illustrated in
Such an arrangement makes it possible to define alternating end abutments. Thus produced, an insert 10 can be held in position between two adjacent tubes 8.
The present invention finds a particular application in heat-exchange devices for a heating, ventilation and/or air conditioning installation designed for motor vehicles, such as an evaporator, a condenser, or a gas cooler or a heating radiator.
Moreover, the examples described above are based on heat-exchange devices comprising tubes of folded types. However, the present invention also covers the embodiments of tubes with plates or of extruded tubes.
Note that the tubes 8 for the circulation of fluid are of “monochannel” type. The tubes 8 described here, are described only as an example. Other types of tubes may be used here as tubes 8 for the circulation of fluid. The present invention also covers the embodiments in which the tubes 8 are furnished with internal partitions delimiting several internal channels. Such tubes are usually called “multichannel tubes”. Therefore, the tubes 8 are known as “multichannel flat tubes”.
This variant has the advantage of reducing the thickness of the core of tubes 8. For this purpose, the tube 8 comprises a localized deformation 32. The localized deformation 32 makes it possible to create a space suitable for receiving the localized extra thickness 30 of the insert 10.
Preferably, the localized deformation 32 is arranged at the end portions 36 of the tube 8. The localized deformation 32 is such that it interacts by matching shape with the localized extra thickness 30 of the insert 10.
According to the example of
The embodiment of
Such an insert 10 is the result, notably, of a reverse double fold, that is to say in two opposite directions, of the metal strip over a first length (A) of the ends of the insert 10. Afterward, this double fold may be reduced in thickness by a thinning operation, preferably by rolling as described above.
Such an embodiment also has the same advantages of holding the inserts 10 in the core of tubes 8 when it is placed under pressure for the installation of the heat-exchange device 2.
The present invention is not limited to evaporators. It has a value for all types of heat-exchange devices such as condensers, gas coolers, heating radiators, etc.
Clearly the invention is not limited to the embodiments described above and is supplied only as an example and encompasses other variants that those skilled in the art could envisage within the context of the claims and notably all the combinations of the various embodiments described above.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR09/00160 | Jan 2009 | FR | national |
