CN101120227B - air cooler - Google Patents

Abstract

An air cooler comprising at least one tubular element (5) having an inner surface (9) and at least one heat-conducting element (11, 11 '), the inner surface (9) defining a passage (10) for air to be cooled in the air cooler, the heat-conducting element (11, 11 ') being secured within the passage (10) and being shaped to divide the passage (10) into a plurality of flow paths (12, 12 '). A medium having a lower temperature than the air to be cooled in the air cooler is caused to flow in contact with the outer surface (8) of the tubular element (5) so that the air in the air cooler is cooled as it flows through the passage (10). The heat-conducting element (11, 11 ') is dimensioned such that it occupies only part of the cross-section of the passage (10), thereby forming an elongate duct (13, 13 ') in the remainder of the passage (10), the cross-sectional area of the elongate duct (13, 13 ') being greater than the cross-sectional area of the respective flow path (12, 12 ') formed by the heat-conducting element (11, 11 ').

Description

air cooler

technical field

The invention relates to an air cooler for cooling compressed air, the air cooler comprising at least one tubular element having an interior defining a passage for the air to be cooled in the air cooler and at least one heat conducting element. surface, a thermally conductive element is fastened within said channel and is shaped to divide the channel into a plurality of flow paths so that a medium at a temperature lower than the air to be cooled in the air cooler flows in contact with the outer surface of the tubular element , so that the air in the air cooler is cooled while flowing through the passage.

Background technique

The amount of air that can be supplied to a vehicle's supercharged internal combustion engine depends not only on the pressure of the air, but also on its temperature. Supplying the largest possible quantity of air to a charged internal combustion engine necessarily requires cooling the compressed air in a charge air cooler before it is led to the internal combustion engine. The charge air cooler is usually located in front of the vehicle's regular radiator. A charge air cooler generally comprises two collecting containers and a plurality of tubular elements arranged in parallel for connecting the collecting containers. The parallel tubular elements are arranged spaced apart from each other to enable ambient cool air to flow between the tubular elements and cool the compressed air in the tubular elements. The compressed air can be cooled to a temperature substantially equal to that of the surrounding air.

The cooling effect of the charge air cooler can be enhanced by fitting one or more folded metal sheets (so-called turbulators) inside the tubular element. Metal sheets divide the tubular element into a plurality of relatively narrow flow paths. The sheet metal provides an additional surface in contact with the compressed air in the tubular element so that the compressed air can be cooled more efficiently. The shape of the sheet metal can also be designed to promote turbulent flow of compressed air. This turbulence further increases the cooling effect of the compressed air passing through the tubular element.

In some climates, the compressed air in the charge air cooler is cooled to a temperature below the air's dew point temperature. Water vapor in the compressed air condenses, with the result that water in liquid form condenses in the charge air cooler. When the temperature of the surrounding air is very low, there is also the danger that water in liquid form will cool down in the charge air cooler and turn into ice. This ice formation on the surface of the metal sheet is severe. Since the sheet metal provides a relatively narrow flow path for the compressed air, this situation entails the danger that ice will block the flow path. Under these conditions, the airflow to the internal combustion engine can be reduced to a level at which operational failure can occur.

US 4 246 963 relates to a heat exchanger preferably used in aircraft. Such heat exchangers consist of cooler banks with separate ducts for cold and hot air. The various ducts are alternately stacked and have substantially vertical lengths passing through the cooler bank relative to each other. Cold air often contains ice crystals. This air directed into the heat exchanger can cause ice to form at the inlet to the cold air duct. This ice formation more or less stops the cool air from flowing through the heat exchanger. To solve this problem, tubular beam elements are arranged at the inlet to the cold air duct. The hot air is guided in parallel through the tubular beam elements and the common ducts for the hot air. The hot air directed through the beam element heats the outer surface of the beam element forming the inlet to the cold air duct. The outer surfaces of the beam elements will thus be at a temperature high enough to prevent ice formation at the inlet to the cold air duct.

Contents of the invention

It is an object of the present invention to provide an air cooler configured to ensure the passage of air through the cooler even if the air is cooled by a medium at a very low temperature.

This object is achieved by the air cooler of the invention, characterized in that the size of the heat-conducting element is such that it occupies only part of the cross-section of the passage, thereby forming a cross-sectional area in the remainder of the passage which is larger than that produced by the heat-conducting element. An elongated conduit of a cross-sectional area corresponding to the flow path formed. When the medium, which may be the ambient air, is at a very low temperature, there is a risk that the water vapor in the air cooled in the air cooler will condense and freeze into ice. This ice formation occurs on the inner surface of the tubular element and on the surface of the heat conducting element. Since the heat-conducting element divides the passage into relatively narrow flow paths, there is clearly a risk that the flow paths will be clogged to varying degrees if ice forms on the surface of the heat-conducting element. Arranging the heat conducting element over only part of the cross-section of the passage forms an elongated conduit in the remainder of the passage. If this pipe is of sufficient size, it is almost certain that it will not freeze. The air flow through the air cooler is thus substantially maintained at all times. Relatively hot air flowing through the elongated tubes can also supply heat to the thermally conductive elements. Ice formed on the heat conducting element can thus gradually melt, thereby clearing the adjacent flow paths.

According to one embodiment of the invention, said elongated duct is arranged on the front side of the tubular element with respect to the flow direction of the medium. On the front side, the medium will initially flow in contact with the surface of the tubular element. This is where the medium temperature is the lowest. The most efficient cooling of the tubular element thus takes place at said front side. This positioning of the elongated duct is usually sufficient to provide quite acceptable cooling of the air in the duct without the aid of heat conducting elements. According to another embodiment, the elongated duct can optionally be arranged on the rear side of the tubular element with respect to the flow direction of the medium. Since the temperature of the medium increases as it flows through the heat conducting element, the cooling effect is less at the rear side of the heat conducting element. There is thus less risk of ice forming on the slender pipe. Thus the elongated duct may be of smaller size. It is also possible to arrange the pipes in the middle part of the passage, and to install the heat conducting elements on the sides opposite to each other.

According to another preferred embodiment of the present invention, the dimension of the cross-sectional profile of the channel in the medium flow direction is larger than the dimension in the direction perpendicular to the flow direction. This configuration of the tubular element results in a relatively elongated contact surface with the flowing medium, thereby promoting cooling of the air in the tubular element. Advantageously, the cross-sectional profile of said elongated duct has substantially the same width as height. If, for example, the pipe has a cross-sectional profile that is insufficient in height or width, there is a clear risk that ice will form in the direction of the underdimensioning of the pipe so that it blocks the pipe. If instead the pipe is oversized in one direction, the result is a pipe that is unnecessarily tall or wide. Such overdimensioned ducts reduce the number of flow paths, resulting in insufficient cooling of the air passing through the tubular element. The optimal pipe is therefore likely to be substantially the same height and width.

According to a preferred embodiment of the invention, the cooler comprises a plurality of tubular elements spaced apart from each other and arranged in parallel in a row such that adjacent tubular elements have gaps in which the medium can flow. The tubular elements can be arranged at a substantially uniform distance from each other. The result is a substantially uniform flow of air in the gaps between adjacent tubular elements. The air is thus cooled to substantially the same temperature in all tubular elements.

According to a preferred embodiment of the invention, the tubular element is made of a material with good thermal conductivity. The result is efficient heat transfer between the medium outside the tubular element and the air inside. The tubular element can be made of aluminum which has good thermal conductivity. The heat-conducting element is preferably likewise made of a material with good heat conductivity. Here again, aluminum is a suitable material. The heat conducting element can be made from folded sheet material. The sheet material provides a contact surface that can be easily shaped so that a suitable flow path is formed in the channel. The contact surfaces can be shaped in such a way as to promote turbulent flow through the flow path. The surface may for example have gill-like structures, resulting in a more efficient cooling of the air in the tubular element.

According to a preferred embodiment of the invention, the cooler is a charge air cooler adapted to cool air at a pressure higher than ambient. The charge air cooler itself is used in the vehicle to cool the compressed air before it is directed to the charged internal combustion engine. The compressed air is usually cooled below the dew point temperature in the charge air cooler, with the result that the water vapor in the air condenses in the charge air cooler. Conventional charge air coolers are usually cooled by ambient air. If the temperature of the surrounding air is very low, there is also the danger that the condensate in the charge air cooler will freeze and form ice. The elongated ducts in the charge air cooler according to the invention make it possible to maintain a sufficient air flow through the charge air cooler for operation of the supercharged internal combustion engine under substantially all circumstances.

Description of drawings

Preferred embodiments of the present invention are described below by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a charge air cooler according to the invention,

Figure 2 shows a cross-section through the charge air cooler along the plane A-A in Figure 1, and

Figure 3 shows a charge air cooler according to an alternative embodiment.

Detailed ways

Figure 1 shows a charge air cooler which can be mounted, for example, at the front of a vehicle driven by a supercharged internal combustion engine which requires a supply of compressed air. The purpose of the charge air cooler is to cool the compressed air before it is introduced into the combustion engine. The charge air cooler comprises an inlet 1 to a first collection vessel 2 for receiving hot compressed air from the compressor. The first collection container 2 comprises a plurality of internal bores, whereby compressed air can be directed to the cooler group 3 extending between the first collection container 2 and the second collection container 4 . The cooler group 3 comprises a plurality of tubular elements 5 extending in a substantially rectilinear manner between the first collection container 2 and the second collection container 4 . The tubular elements 5 are stacked parallel in the vertical direction. The tubular elements 5 are arranged substantially equidistant from each other such that there are regular gaps 7 between adjacent tubular elements 5 . Ambient air can thus flow through said gap 7 between adjacent tubular elements 5 . The flow of ambient air through the cooler bank 3 can be caused by the movement of the vehicle and/or by the radiator fan pulling air through the cooler bank 3 . The second collection container 4 comprises an internal bore for receiving cooled compressed air from the corresponding tubular element 5 . The cooled compressed air is led out of the second collection container 4 via the outlet 6 before being led through a suitable line into the supercharged internal combustion engine.

FIG. 2 shows a cross-sectional view of four tubular elements 5 of a cooler group 3 . The tubular element 5 is of the same construction. The tubular element 5 is made of a material with high thermal conductivity, such as aluminium. The tubular element 5 has a substantially elongated profile in cross-section and has two substantially planar opposite long sides 5a, 5b. The opposite long sides 5a, 5b are connected by two opposite short sides 5c, 5d, and the short sides 5c, 5d are circular shapes convex outward. The tubular element 5 has an outer surface 8 defining a contact surface with the surrounding air. The tubular element 5 has an inner surface 9 which defines a passage 10 for the compressed air to be guided between the collection containers 2 , 4 .

Each tubular element 5 comprises a heat conducting element 11 secured within the passage 10 and in contact with the inner surface 9 at several points. A heat conducting element 11 is arranged in the passage 10 to increase the cooling contact surface with the compressed air directed through the passage 10 . The heat conducting element 11 is made of a material with good heat conductivity, such as aluminum. The heat conducting element 11 may be made of a sheet of aluminum which is folded so as to divide the channel into a plurality of substantially parallel flow paths 12 . Each flow path 12 thus has a relatively limited cross-sectional area. The compressed air flowing through the channels 10 in each tubular element 5 is adapted to be cooled by the surrounding air. The ambient air has a main flow direction 14 towards the cooler group 3 , which direction is substantially parallel to a plane 15 extending centrally through the vertically stacked tubular elements 5 . However, part of the ambient air encounters the front short side 5c of the tubular elements 5 before flowing through the gap 7 between two adjacent tubular elements 5 . The temperature of the ambient air is usually significantly lower than the temperature of the compressed air in the tubular element 5 . When the ambient air comes into contact with the outer surface 8 of the tubular element 5 it causes cooling of the outer surface 8 . Since the tubular elements 5 and the heat conducting elements 11 are made of a material with good thermal conductivity, they also provide effective cooling to the inner surface 9 and the heat conducting elements 11 of the respective tubular elements 5 . The inner surface 9 and the heat conducting element 11 thus provide a very effective cooling of the compressed air in the passage 10 of the respective tubular element 5 .

When the temperature of the surrounding air is low, the compressed air in the charge air cooler can be cooled to a temperature below the dew point of the compressed air. In this case, the water vapor in the compressed air condenses, with the result that water in liquid form condenses in the channels 10 of the respective tubular elements 5 . If the temperature of the surrounding air is very low, there is a risk that the condensate will freeze and form ice in the channel 10 . This ice will form on the inner surface 9 of the tubular element 5 and on the surface of the heat conducting element 11 . Since the heat-conducting element 11 comprises a flow path 12 with a relatively small cross-sectional area, there is a distinct risk that the flow path 12 will become clogged to varying degrees if ice forms on the surface of the heat-conducting element 11 . This situation can lead to malfunctions in the operation of the internal combustion engine due to insufficient air supply.

However, according to the invention, the heat-conducting element 11 is dimensioned such that it occupies only part of the cross-section of the passage 10, so that the remainder of the passage cross-section forms a cross-sectional area larger than the respective flow path 12 formed by the heat-conducting element 11. The cross-sectional area of the pipe 13. In Fig. 2, the heat conducting element 11 is arranged in the channel 10 in such a way that said duct 13 is formed on the front short side 5c of the tubular element 5 with respect to the flow direction 14 of the surrounding air. In this case, the elongated ducts 13 have substantially the same height and width. The conduit 13 is at least not so narrow in either direction that the risk of the conduit 13 being frozen increases. Suitably sized such passages 13 enable the airflow through the charge air cooler to be maintained substantially at all times when the ambient temperature is very low and the flow passage 12 freezes. The compressed air in the duct 13 also provides heat to the heat conducting element 11 . Therefore, the ice formed on the heat conduction element 11 can be gradually melted, so that the blocked flow path 12 can recover its air conduction function.

Figure 3 shows a cross-sectional view of four tubular elements 5 according to an alternative embodiment.

In this case, the heat conducting element 11' is arranged in the passage in such a way that a duct 13' is formed on the rear short side 5d of the tubular element with respect to the flow direction 14 of the surrounding air. Here again, the cross-sectional shape of the elongated duct 13' has substantially the same height as the width. The heat conducting element 11' is folded in such a way that the passage is divided into a plurality of substantially parallel flow paths 12' of smaller cross-sectional area. The heat conducting element 11' is also provided with a surface having protrusions and holes, thereby promoting turbulent flow of air through the flow path 12'. The heat conducting element 11' thus provides very effective cooling of the compressed air as it passes through the flow path 12'. The cooling air flow leads to a gradually increasing temperature along the elongated gap 7 . The cooling effect at the rear end side 5d of the tubular element is therefore not the same as at the front short side 5c, thereby further reducing the risk of the pipe 13' freezing. Suitable dimensions of such ducts 13' make it possible to maintain the air flow through the charge air cooler at all times when the ambient temperature is very low. The compressed air in the pipe 13' also provides heat to the heat conducting element 11', so that the ice formed on the heat conducting element 11' can gradually melt.

The invention is in no way limited to the embodiments described with respect to the figures, but may be varied freely within the scope of the claims. A plurality of separate heat conducting elements may be arranged in the passage. The elongated conduits may be placed in any desired portion of the pathway.

Claims (9)

1. An air cooler for cooling compressed air, the air cooler comprising at least one tubular element (5) and at least one heat conducting element (11, 11'), the tubular element (5) having a defined The inner surface (9) of the channel (10) of the cooled air in the air cooler, the heat conducting elements (11, 11') are fastened in said channel (10) and the shape is designed to divide the channel (10) into multiple flow paths (12, 12') so that the medium having a lower temperature than the air to be cooled in the air cooler flows in contact with the outer surface (8) of the tubular element (5), so that the air in the air cooler The air is cooled while flowing through said passage (10), characterized in that the heat-conducting element (11, 11') is dimensioned such that it occupies only part of the cross-section of the passage (10) so that the passage Formed in the remainder of (10) are elongated ducts (13, 13') having a cross-sectional area greater than that of the corresponding flow paths (12, 12') formed by the heat conducting elements (11, 11'). 2. Air cooler according to claim 1, characterized in that said elongated duct (13) is arranged on the front side (5c) of the tubular element with respect to the flow direction (14) of the medium. 3. Air cooler according to claim 1, characterized in that said elongated duct (13) is arranged on the rear side (5d) of the tubular element with respect to the flow direction (14) of the medium. 4. The air cooler according to any one of claims 1-3, characterized in that: the dimension of the cross-sectional profile of the passage (10) in the medium flow direction (14) is larger than that perpendicular to the flow direction Dimensions in the direction of (14). 5. An air cooler according to any one of claims 1-3, characterized in that the cross-sectional profile of the elongated duct (13, 13') has the same width as the height. 6. An air cooler according to any one of claims 1-3, characterized in that the cooler comprises a plurality of tubular elements (5) spaced apart from each other and arranged in parallel in a row such that adjacent tubular elements Between (5) there is a gap (7) through which the medium can flow. 7. An air cooler according to any one of claims 1-3, characterized in that the tubular element (5) is made of a material with good thermal conductivity. 8. The air cooler according to any one of claims 1-3, characterized in that the heat conducting element (11, 11') is made of a material with good heat conductivity. 9. Air cooler according to claim 8, characterized in that the heat conducting element (11, 11') is made of folded sheet material.

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