FAN WITH HEAT CUBE MADE OF THERMALLY CONDUCTIVIC PLASTIC

Description

[0001] The invention relates to a fan with a heat sink designed as a plastic cover.

[0002] A heat sink's function is to absorb heat from the component being cooled and transfer it to the surrounding medium. Heat sinks are typically made of a material with high thermal conductivity, such as aluminum or copper.

[0003] Mass production of aluminum heat sinks, especially those whose shape is adapted to a predetermined application, is usually carried out using the die-casting process. In this process, heated aluminum in a liquid or pasty state is pressed under high pressure into a preheated steel mold, which then later serves as the conductive heat sink.

[0004] Heat sinks are also used in motors. For example, DE 19841583 A1 deals with a heat sink for cooling components, in particular semiconductor components, motors and assemblies, especially a cooling unit made at least partially of extruded aluminum or other light metal, consisting of at least two separate base profiles for mounting the electrical components, which are spaced apart from each other and connected to each other by means of a plurality of separate cooling fins. The mounting of at least one fan is also provided between two adjacent base profiles.

[0005] For cooling, heat conduction is a suitable method. In physics, heat conduction—also called thermal diffusion or conduction—refers to the flow of heat resulting from a temperature difference. According to the second law of thermodynamics, heat always flows only in the direction of lower temperature, i.e., towards the heat sink. Heat conduction is a mechanism for transporting thermal energy without requiring a macroscopic flow of material, unlike the alternative mechanism of convection. Heat transport by thermal radiation is also considered a separate mechanism. A measure of heat conduction in a particular material is its thermal conductivity.

[0006] It is therefore logical that a material with good to very good thermal conductivity is used for cooling with a heat sink. Copper and its alloys have typical thermal conductivities of 100–400 W / mK, while aluminum, at 236 W / mK, also falls within a range of high thermal conductivity. Even unalloyed steel, as a metallic material, has a significantly poorer thermal conductivity, possessing a thermal conductivity of around 50 W / mK.

[0007] Industrial plastics such as PUR or polyamide (PA) are considered unsuitable as heat conductors in the current state of the art due to their significantly lower conductivity, which is less than 1 / 1000th that of copper. Copper, therefore, has a conductivity more than 1000 times better than a conventional plastic.

[0008] Fans and fan motors with integrated electronics naturally generate heat and therefore require cooling to prevent damage and extend their lifespan. While typical metal covers dissipate heat effectively, they are expensive to manufacture and, due to the high cost of materials, not cost-effective.

[0009] Further prior art in the present technical field is disclosed in documents KR 101 345 703 B1, US 2016 / 069 352 A1, JP 2005 168 133 A, US 2014 / 325 829 A1, DE 10 2009 045 063 A1, DE 10 2015 121 166 A1 and US 2016 / 087 511 A1.

[0010] The invention is therefore based on the objective of providing a cost-effective and reliably functioning cooling system for the electronics of a fan motor.

[0011] This problem is solved by the combination of features according to claim 1.

[0012] A key concept of the present invention is to cool the electronics of a fan using a plastic heat sink instead of a metallic one. This approach, unknown in the prior art, is achieved by using a heat sink as a cover with a very thin wall thickness and a specific shape and surface area. In addition to increasing the surface area, several effects are specifically and cumulatively utilized, namely heat conduction, heat convection, and the reduction of heat build-up, by using a thin-walled plastic material with a large, efficient surface area and a comparatively large proportion of it in direct contact with heat-generating components.

[0013] In this way, departing from the state of the art, a cover can also be obtained cheaply and efficiently using a plastic material, which enables thermal dissipation of the heat generated.

[0014] According to the invention, a fan comprising electronics on a printed circuit board is provided, with a cover above the electronics that acts as both an active and a passive heat sink. The cover is essentially designed as a flat lid element made of a thin-walled plastic and has a shape that provides a surface area for cooling the electronics located beneath the cover, which is at least twice the size of the projected base area of ​​the cover. According to the invention, the cover has a cooling fin structure with multiple cooling fins, which increase the effective surface area. It is further advantageous if the cover has several recesses in which mounting openings are provided, allowing the cover to be detachably attached to the fan via releasable fasteners.

[0015] According to the invention, the cover in the area of ​​the cooling fin structure has a flat contact surface in direct contact with heat-producing components.

[0016] In a further advantageous embodiment of the invention, it is provided that the cover has the cooling fin structure in one or more areas or forms several areas with such a cooling fin structure.

[0017] Furthermore, it is advantageous if the cooling fins are arranged or designed radially outwards, which allows for a structure open radially outwards and upwards, which has a beneficial effect on the manufacturing and the cooling effect.

[0018] A further improvement can be achieved by having the cooling fins have a varying wall thickness, particularly decreasing towards the outside. Other shapes and wall thickness configurations are also conceivable to improve heat dissipation. In principle, unlike the thick-walled metallic bodies typically used in the prior art, the concept of the present invention aims for an overall thin wall thickness to achieve rapid heat dissipation and prevent heat buildup.

[0019] According to the invention, the cover forms a flat contact surface on the underside facing the electronics and, in the assembled state, this contact surface rests against electronic components at least partially.

[0020] In an advantageous embodiment of the invention for a radial fan, the cover is formed from a substantially round section to which a projection (preferably with a linearly extending side edge) is integrally attached.

[0021] It has also proven advantageous if the cover material is polyamide (PA), polyurethane (PUR), polycarbonate (PC) or polyethylene (PE).

[0022] According to the invention, the thickness of the cover in the area parallel to the arrangement of the printed circuit board and / or in the area of ​​the flat contact surface is at least twice as thin as in an edge region or an area of ​​the cover extending towards the electronics. This allows the essential stabilizing properties to be concentrated in the edge region and the essential thermal properties in the flat area and the areas with the cooling fins.

[0023] Other advantageous embodiments of the invention are characterized in the dependent claims and are described in more detail below together with the description of the preferred embodiment of the invention with reference to the figures.

[0024] They show: Fig. 1 a schematic sectional view through a radial fan, Fig. 2 a perspective view of the radial fan from Figure 1 , Fig. 3 a top view of the cover of the electronics of the radial fan made of Figure 1 , Fig. 4 a perspective view of the cover made of Figure 3 , Fig. 5 a sectional view through the cover made of Figure 3 .

[0025] The invention is described below using an exemplary embodiment with reference to the Figures 1 to 5 explained in more detail, whereby identical reference symbols indicate identical structural and / or functional features.

[0026] The Fig. 1shows a schematic cross-sectional view through a fan 1, here a radial fan.

[0027] The fan 1 is equipped with electronics on a circuit board 2.

[0028] Above the electronics, a cover 10 according to the invention is shown, which is designed as both an active and a passive heat sink. The cover 10 is, as shown in the Figures 3 to 5 The cover element is essentially formed as a flat lid element made of a thin-walled plastic and has a shape that provides a surface 11 effective for cooling the electronics arranged under the cover 10, which, compared to the projected base area of ​​the cover 10, is formed by the Figure 2 The visible cooling fin structure with multiple cooling fins (12) is at least twice as large. As can also be seen, the cooling fins extend radially outwards.

[0029] The projected floor area is derived from the diagram in the top view. Figure 3 As additionally stated in the Figure 5 As can be seen, the ribbed structure significantly increases the effective surface area. The cover 10 is formed from an essentially central round section 17 to which a projection 18 with a straight side edge is integrally attached.

[0030] In the Figures 3 and 4 It can be seen that the cover 10 forms several recesses 13 in which fastening openings 14 are provided.

[0031] The cover 10 is detachably attached to the fan 1 via removable fasteners 15 (e.g., screws) in conjunction with the electronics. The underside of the cover 10, facing the electronics, forms a flat contact surface so that, when installed, it rests at least partially against electronic components.

[0032] In the sectional view through cover 10, as shown in the Fig. 5 As shown, this cooling fin structure has a flat contact surface 16 for contacting heat-generating electronic components. It can also be seen that the cooling fins 12 have a changing wall thickness, decreasing slightly from bottom to top, and thus taper slightly conically.

[0033] The invention is not limited in its implementation to the preferred embodiments specified above. Rather, it is conceivable to adapt the shape and design of the lid to the respective requirements and, for example, to adjust the number of areas with ribbed structures to the specific cooling task. However, the scope of protection of the invention is exclusively defined by the following claims.

Claims

1. A fan (1) comprising an electronic system on a printed circuit board (2) and a cover (10) arranged above the electronic system, which is embodied both as an active cooling body and a passive cooling body, wherein the cover (10) has a cooling fin structure with a plurality of cooling fins (12), wherein the cover (10) is designed substantially as a flat covering element made of a thin-walled plastic material and has a shape with a surface (11) which is effective for the cooling of the electronic system arranged beneath the cover (10), said surface being greater than the projected base area of the cover (10) by a factor of at least 2 due to the cooling fin structure with the plurality of cooling fins (12), wherein the cover (10) has a flat contact side (16) in contact with heat-producing components of the electronic system in the region of the cooling fin structure, and wherein the cover (10) is designed with a flat contact surface on the bottom side facing the electronic system, said contact surface at least partially contacting electronic components when mounted, characterised in that the thickness of the cover (10) in the region parallel to the arrangement of the printed circuit board (2) and / or in the region of the flat contact surface is less than in an edge region or a region of the cover (10) extending towards the electronic system at least by a factor of 2.

2. The fan (1) according to claim 1, characterised in that the cover (10) is designed with a plurality of recesses (13) in which securing openings (14) are provided at which the cover (10) is detachably secured to the fan (1) by detachable securing means (15).

3. The fan (1) according to claim 2, characterised in that the cover (10) has the cooling fin structure in one or multiple regions.

4. The fan (1) according to any one of preceding claims 2 or 3, characterised in that the cooling fins (12) are attached or designed to extend radially outwards.

5. The fan (1) according to any one of preceding claims 2 to 4, characterised in that the cooling fins (12) possess a wall thickness which is variable, in particular decreasing towards the outside.

6. The fan (1) according to any one of the preceding claims, characterised in that the cover (10) is designed from a substantially round portion (17) integrally followed by a cantilever (18).

7. The fan (1) according to any one of the preceding claims, characterised in that the material of the cover (10) is a polyamide (PA), polyurethane (PUR), polycarbonate (PC) or polyethylene (PE).

8. The fan (1) according to any one of the preceding claims, characterised in that the fan is a radial fan.