WO2010006875A1

WO2010006875A1 - Improved heat sink, frequency converter comprising said heat sink and method for producing said heat sink

Info

Publication number: WO2010006875A1
Application number: PCT/EP2009/057639
Authority: WO
Inventors: Francesco Battistella
Original assignee: Amer S.P.A.
Priority date: 2008-06-23
Filing date: 2009-06-18
Publication date: 2010-01-21
Also published as: ITVI20080147A1

Abstract

The invention concerns a heat sink (3) comprising wings (5) associated with a support plate (4) at the level of corresponding bases (5a). The support plate (4) is provided with seats (6) matching the bases (5a) of the wings (5) in order to house them.

Description

"IMPROVED HEAT SINK, FREQUENCY CONVERTER COMPRISING SAID

HEAT SINK AND METHOD FOR PRODUCING SAID HEAT SINK".

DESCRIPTION

The present invention concerns a heat sink, particularly suitable for cooling an electronic device like, for example, a frequency converter.

The present invention also concerns a frequency converter comprising the above mentioned heat sink.

The invention finally concerns a method for the production of the above mentioned heat sink, As is known, many electronic devices, including frequency converters, produce a considerable quantity of heat and therefore need to be adequately cooled.

Said cooling action is generally achieved by means of heat sinks that, as is known, comprise wings connected at the base to a support plate, which in its turn is placed in thermal contact with the device to be cooled. The wings are usually immersed in ambient air with forced convection and develop a large heat exchange surface, allowing effective heat dissipation to be obtained.

According to a known embodiment of the invention, the wings and the plate of the heat sink are obtained in a single piece, extruded from a highly conductive malleable material like, for example, aluminium.

However, the above mentioned technique is not suitable for obtaining compact heat sinks that, in order to provide large heat exchange surfaces in reduced spaces, require high and thin wings, arranged next to one another.

In fact, in order to obtain the entire heat sink from a single extrusion cycle, the extrusion die to be provided would be too fragile and therefore would tend to break very frequently.

The known technique used in these cases involves, instead, the extrusion of each individual wing, which is shaped substantially as shown in Figure 1 by way of example. As shown in the figure, each wing has a substantially H-shaped section, with a central core B having considerable height compared to its thickness and ends

C, D enlarged compared to the core B.

The ends C, D are provided with joints for connection with other analogous wings, in such a way as to advantageously obtain a modular heat sink A. The above mentioned known construction form makes it possible to obtain heat sinks that develop a large heat exchange surface per unit of volume.

However, it poses a first drawback represented by the fact that the extrusion of each individual wing separately from the others is a more complex and costly process than a single extrusion cycle as described above. In particular, as the wings require a geometry and dimensional precision such as to ensure their mutual coupling, the related extrusion dies are more expensive and need to be replaced more frequently.

Therefore, the heat sink is more expensive than a heat sink of the type previously described offering analogous performance levels, Furthermore, since the coupling of the wings generates irregularities on the contact surface of the heat sink, there is the need to proceed to a successive rectification operation intended to avoid jeopardizing the contact with the surface of the device to be cooled, involving another drawback that lies in a further increase in the cost of the heat sink. Another, yet not the least drawback is represented by the fact that the high cost of the heat sink considerably affects the final cost of the frequency converter, or the electronic device with which the heat sink is combined.

The object of the present invention is to overcome all the drawbacks described above. In particular, it is a first object of the invention to provide a heat sink that is less expensive than the heat sinks of known type described above, as well as a method for producing the same.

It is also the object of the invention to provide a frequency converter that costs less than an equivalent frequency converter of known type. The objects described above are achieved by a heat sink carried out according to the main claim, as well as by a method for producing said heat sink implemented according to claim 15.

The same objects are also achieved by a frequency converter equipped with the heat sink of the invention, according to claim 13. The said objects and advantages, which will be highlighted in greater detail below, are illustrated in the description of a preferred embodiment of the invention which is provided by way of non-limiting example with reference to the attached drawings, wherein:

- Figure 1 shows a cross section of a heat sink of known type; - Figure 2 shows an axonometric view of the frequency converter of the invention, equipped with the heat sink of the invention;

- Figure 3 shows a front view of the frequency converter of Figure 2;

- Figure 4 shows a component of the frequency converter shown in Figure 2. The frequency converter of the invention is illustrated in Figure 2, where it is indicated as a whole by 1 , and comprises a support base 1a for an electronic device 2 schematically shown in Figure 3 and known per se.

The frequency converter 1 also comprises a heat sink 3, thermally connected to the support base 1a in order to remove the heat produced by the electronic device 2. It is clear that the heat sink 3 of the invention can be applied to devices different from frequency converters, in particular electric or electronic devices that require very compact and efficient heat sinks.

The heat sink 3 comprises a series of wings 5 provided with a base 5a associated with a support plate 4. According to the invention, the support plate 4 is provided with seats 6 matching the bases 5a of the wings 5, so that each wing 5 is housed in the seats 6, preferably with a slight interference.

It can therefore be understood that the heat sink 3 is constructed in a very simple manner, by inserting the wings 5 directly in the seats 6 so as to avoid the need to assemble them together in advance.

Avoiding the assembly of the wings 5 means avoiding the rectification operation on the coupling surface, which simplifies the production process and thus reduces its overall cost.

In particular, each wing 5 is a thin body 8 with uniform thickness W, defining an edge 8a that is coupled with the support plate 4 at the level of the corresponding seats 6.

Advantageously, the thin bodies 8 can be obtained from a sheet of material with constant thickness easily available on the market, for example a strip, thus allowing the production costs of the heat sink 3 to be considerably reduced. Furthermore, the thin bodies 8 can be obtained from the sheet of material by means of a shearing operation, which is considerably simpler than the extrusion technique adopted in the known art.

The shearing of the wings 5 from a sheet of thin material offers, compared to extrusion, the further advantage of allowing lower thickness values W to be obtained, near to the minimum structural stability limit of the wings 5. Consequently, and advantageously, it is possible to provide a higher number of wings 5 in the same volume, and therefore to increase the overall surface of the heat sink 3 with the same overall dimensions.

Furthermore, a reduced thickness W of the wings 5 makes it possible to reduce their overall weight, with the further advantage of reducing the cost of the material compared to a heat sink of known type with equivalent dissipation surface.

It can be understood, therefore, that the use of thin bodies 8 considerably contributes to achieving the object to reduce the cost of the heat sink, The sheet of material is preferably aluminium, offering advantages such as reduced weight, high workability and optimum thermal properties.

The seats 6 are visible in particular in Figure 4 where, for the sake of simplicity, the wings 5 have been omitted.

Preferably, and as shown in the figure, each seat 6 is a slot 7 that develops mainly along a longitudinal direction X and houses a corresponding thin body 8 at the level of the corresponding edge 8a.

The slots 7 preferably have a constant width L along the above mentioned longitudinal development direction X and the thickness W of the thin bodies 8 exceeds the above mentioned width L. In this way a coupling by interference is obtained, which advantageously favours the heat exchange between the wings 5 and the support plate 4.

The ratio between the thickness W and the width L is preferably less than 1.1 , so that a fair compromise is achieved between the opposing needs to guarantee heat transfer and at the same time facilitate the insertion of the wings 5 in the seats 6.

According to a construction variant of the invention, not illustrated herein, the slots 7 are provided with localized throttled parts suited to favour the assembly stability of the wings.

The slots 7 are preferably arranged parallel to one another and determine an arrangement of the wings 5 according to parallel planes.

Owing to the arrangement just described, the wings 5 define a series of channels for the passage of the cooling air, which can thus come into contact with the surface of the wings in an optimal way, thus advantageously achieving effective removal of heat. The cost of the heat sink 3 and the complexity of the production process are further reduced by employing wings 5 that are polygonal, preferably rectangular, in shape.

Construction variants of the invention may also include wings 5 whose shape is other than rectangular and which are arranged in a different manner than described above.

By way of example, in one of the above mentioned variants the thin bodies 8 can be arranged according to planes that are transversal to the longitudinal direction X of the seats 6, and the corresponding edges 8a can have different profiles matching the profile of the cross section of the support plate 4 according to the above mentioned transversal planes.

The support plate 4 is preferably incorporated in the support base 1a of the converter 1 , as shown in Figure 4, which illustrates the support base 1a without the other components, for the sake of clarity.

Advantageously, the construction of the support plate 4 in a single piece with the support base 1a reduces the complexity of the production process and consequently reduces the overall cost of the heat sink 3 and of the converter 1.

Preferably but not necessarily, the support base 1a and the heat sink 3 are both made of aluminium that, advantageously, is light, easy to work and has optimal thermal properties. The method for producing the heat sink 3 of the invention comprises a first operation for producing the wings 5 separately from the support plate 4 of the heat sink 3.

According to the method, furthermore, a plurality of seats 6 whose profile matches the bases 5a of the wings 5 is provided in the support plate 4. The method also includes a further operation for inserting the wings 5 in the above mentioned seats 6 at the level of the corresponding bases 5a.

As already explained, the wings 5 are obtained preferably by shearing from a sheet of material with uniform thickness W, not represented herein, and inserted in the seats 6 by interference. As regards, on the other hand, the arrangement of the seats 6 on the support plate 4, it takes place at the same time as the production of the support plate 4 itself, preferably by die casting.

It is evident, however, that in construction variants of the invention the seats 6 can be created after producing the support plate 4, for example by mechanical machining with chip removal. Since according to the method of the invention the wings 5 must be inserted in the seats 6, this makes it possible to avoid the rectification operations that are necessary in the production methods of known type, as the thermal contact between the wings 5 and the support plate 4 in ensured by their mutual coupling.

Furthermore, as the wings 5 are obtained by shearing from a sheet of material, the extrusion cycle typical of the known methods for manufacturing heat sinks is avoided. The features considered above make the method described simpler than the methods of known type.

Obviously, the greater simplicity of the method described above makes it possible to limit the production costs of the heat sink of the invention compared to equivalent heat sinks of known type, thus achieving one of the objects of the invention. The above shows that the heat sink, the frequency converter and the method of the invention achieve all the set objects.

Upon implementation, further changes or variants departing from the above description will be possible. Said changes and variants may regard, in particular, the number of wings of the heat sink, as well as their shape and their arrangement in the frequency converter.

In any case, the above mentioned changes or variants, even if they are neither described herein nor illustrated in the drawings, must all be considered protected by the present patent, provided that they fall within the scope of the following claims.

Where technical features mentioned in any claim are followed by reference signs, those reference sings have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1 ) Heat sink (3) comprising a plurality of wings (5) associated with a support plate (4) at the level of corresponding bases (5a), characterized in that said support plate (4) is provided with seats (6) matching said bases (5a) of said wings (5) in order to house them.

2) Heat sink (3) according to claim 1 ), characterized in that each one of said wings (5) is a thin body (8) that defines an edge (8a) suited to ensure the coupling with said support plate (4).

3) Heat sink (3) according to claim 2), characterized in that said thin body (8) has uniform thickness (W).

4) Heat sink (3) according to claim 3), characterized in that each one of said seats (6) is a slot (7) developed mainly along a longitudinal direction (X).

5) Heat sink (3) according to claim 4), characterized in that said slot (7) has substantially constant width (L) along said longitudinal direction (X).

6) Heat sink (3) according to claim 5), characterized in that each one of said slots (7) houses the edge (8a) of a corresponding one of said thin bodies (8).

7) Heat sink (3) according to claim 6), characterized in that said thickness (W) of each thin body (8) exceeds said width (L) of said slot (7).

8) Heat sink (3) according to claim 7), characterized in that the ratio between said thickness (W) and said width (L) is less than 1.1.

9) Heat sink (3) according to claim 4), characterized in that the profile of said edge (8a) of each thin body (8) matches the profile of the cross section of said support plate (4) in relation to a plane transversal to said longitudinal direction (X).

10) Heat sink (3) according to any one of the claims from 4) to 9), characterized in that said slots (7) are arranged parallel to one another.

11 ) Heat sink (3) according to claim 10), characterized in that said wings (5) are arranged parallel to one another.

12) Heat sink (3) according to any one of the preceding claims, characterized in that said wings (5) have a substantially polygonal shape.

13) Frequency converter (1 ) comprising a support base (1 a) for an electric or electronic device (2), characterized in that it comprises a heat sink (3) according to any one of the preceding claims, thermally connected with said support base (1 a).

14) Frequency converter (1 ) according to claim 13), characterized in that said support plate (4) of said heat sink (3) belongs to said support base (1 a). 15) Method for producing a heat sink (3) of the type comprising a support plate (4) and a plurality of wings (5) associated with said support plate (4) at the level of a base (5a), characterized in that it comprises the following operations:

- producing said wings (5) separately from said support plate (4); - preparing, in said support plate (4), a plurality of seats (6) whose profile matches the bases (5a) of said wings (5);

- inserting said wings (5) in said seats (6) at the level of the corresponding bases (5a).

16) Method according to claim 15), characterized in that said wings (5) are obtained from a sheet of material.

17) Method according to claim 16), characterized in that said wings (5) are obtained by shearing from said sheet of material.

18) Method according to any one of the claims 16) or 17), characterized in that said sheet of material has uniform thickness (W). 19) Method according to any one of the claims from 15) to 18), characterized in that said seats (6) are created at the same time as said support plate (4) is produced.

20) Method according to claim 19), characterized in that said support plate (4) with said seats (6) is produced through a die-casting process. 21 ) Method according to any one of the claims from 15) to 20), characterized in that said insertion of said wings (5) in said seats (6) takes place by interference.