Device for cooling the electric motor of a fan, fan, and method for cooling the electric motor of a fan

Abstract

The invention relates to a device for cooling the electric motor of a fan with air, wherein during operation the fan generates a pressure difference between the inflow side and electric motor and the outflow side and wherein the pressure difference is used to guide cooler ambient air from the outflow side to the electric motor.

Description

[0001] DEVICE FOR COOLING THE ELECTRIC MOTOR OF A FAN, FAN AND METHOD FOR COOLING THE ELECTRIC MOTOR OF A FAN

[0002] The present invention relates to a device for cooling the electric motor of a fan with air, a fan with such a device and a method for cooling the electric motor of a corresponding fan.

[0003] Fans of this generic type are well known in practice. Reference is made to WO 2020 / 015792 A1 for an example.

[0004] Fans are often operated under high thermal loads, for example at temperatures > 60°C. Particularly in "suction" configurations, where, for example, hot air from a heat exchanger is sucked through a fan, problems arise with fan components. EC fans in particular have integrated electronics with temperature-sensitive components. Other components of the fan, such as bearings, insulation materials, winding wires, etc. are also subject to certain upper temperature limits, which limit the performance or speed. It is not uncommon for the motor to be cooled using air warmed or heated by the heat exchanger, since the electric motor is located in the conveying medium flow of the main fan flow. This also applies if the motor or its housing is surrounded by cooler ambient air.

[0005] The invention is based on the object of eliminating, or at least reducing, the disadvantages occurring in the prior art. To this end, a special device for cooling the electric motor is to be specified, in which sufficiently good cooling can be achieved using simple means. Such cooling is to be achieved by utilizing the flow characteristics and functions inherent in the fan. Furthermore, the device according to the invention is to be distinguished from competing devices. The same applies to the fan according to the invention and the method according to the invention. The above object is achieved with regard to the device according to the invention by the features of claim 1, according to which the fan generates a pressure difference between the upstream side or electric motor and the downstream side during operation, and the pressure difference is used to direct cooler air from the downstream environment to the warm electric motor.There, cooling occurs due to the cooler air. According to the invention, a method for cooling the electric motor of a fan is thus realized, whereby the fan conveys a warmer flow medium. Cooling occurs with cooler air present in the area surrounding the fan on the downstream side. According to the invention, the fan's own flow drive is thus utilized.

[0006] In other words, the electric motor is at least partially cooled by cool ambient air that surrounds the fan at a higher pressure level in an area associated with the downstream side (fan pressure side). The invention takes advantage of the fact that negative pressure regularly prevails in the motor area, i.e., a lower static pressure compared to the downstream side and the pressure-side environment there. The invention utilizes a device that directs cooler ambient air to the motor in a targeted manner and based on the previously discussed pressure difference, where it is used for cooling. The air then returns to the downstream side together with the main fan flow.

[0007] A key advantage of the device according to the invention is that the cooling, in its fluidic function, relies exclusively on the flow-pressure field generated by the fan, using only the fan's own flow drive. Therefore, special structural measures or redesigns of the fan are generally not required.

[0008] A cooling pot can be provided that surrounds the electric motor or its stator and / or its electronics housing, which can be easily integrated into the fan arrangement. This cooling pot can have a largely enclosed area, at least on the flow side and radially outward, defining an environment filled with cooling air that has a lower temperature level than the main fan flow. This enclosed area is preferably provided in a region of the fan arrangement close to the axis.

[0009] A further additional component can be a suction line that connects the interior of the cooling pot with the pressure-side or downstream environment of the fan. The suction line can be designed in the form of a suction pipe. In the downstream environment, the pressure level and temperature level are higher than that of the main fan flow drawn in through the fan inlet nozzle. This is due to the fact that at the point of inflow into the suction line, at least some of the air is from a free environment with a lower temperature level than in the area of ​​the engine, e.g. from an atmospheric environment or from a free, moderately temperature-controlled room. Depending on the arrangement of the suction line or suction pipe, the cooler air flows through the suction line into the cooling pot, if one is provided, or at least to the engine and its components, based on the pressure difference.

[0010] It is further advantageous if the cooling pot has openings on the fan inlet side or toward the impeller or its hub, through which cooling air can flow from the cooling pot toward the impeller hub. The cooling flow flowing from the cooling pot can be directed so that it flows into a main cooling system of the electric motor, for example, heat-dissipating cooling fins can be formed on a flange of the electric motor's stator. Other suitable heat exchange measures can also be provided alternatively or in addition.

[0011] It is also conceivable for the cooling pot to be arranged close to the axis or hub in an area downstream of the impeller, where the main fan flow has significant circumferential speeds. This results in a pressure field which has a significantly lower static pressure level radially inward, i.e. close to the axis, than is the case radially further outward. This is particularly true compared to an outer area on the casing. Cooling air flows through the suction line towards the cooling pot or into the cooling pot and then through openings in the cooling pot to the outside or towards the inflow side of the fan, preferably into a cooling system integrated into the motor. The cooling air then mixes with the main fan flow.

[0012] From a design perspective, it is advantageous if the cooling chamber and / or the suction line are integrated as a single piece into a supporting structure for the motor and impeller. This integration can advantageously be realized in a supporting fan guide vane unit.

[0013] It is also conceivable that flow guides are provided in the cooling pot, which direct the cooling air at relatively high speed and / or high turbulence close to a wall surface of the electronics housing or stator that is to be cooled. This promotes the cooling effect.

[0014] The fan according to the invention solves the problem mentioned at the outset by the features of the independent claim 13, wherein this fan comprises a device according to the invention corresponding to the above embodiments.

[0015] It's conceivable that the fan draws in air on its inlet side that has previously passed through a heat exchanger. This raises the air temperature.

[0016] In advantageous embodiments, it is also conceivable that no cooling chamber surrounding the motor is provided, but rather that the cooling air, after passing through one or more intake lines, is directed into an area within the motor (or its electronics housing and / or its stator). For this purpose, the intake line is connected directly or indirectly to an interface on the motor provided for the cooling air inlet.

[0017] If cooling air enters the interior of an engine from one or more intake lines, an internal cooling air duct or one or more internal cooling air areas are advantageously formed there, through which the cooling air flows, absorbing the engine's waste heat. After flowing through the interior of the engine, the heated cooling air flows out again from the engine interior, for which purpose one or more cooling air outlets are provided.

[0018] Advantageously, internal cooling air ducts or cooling air areas, if designed, through which a cooling air flow sucked in via one or more suction lines flows, are designed to be encapsulated from electronic areas or winding areas or other electrical or electronic components, so that no possibly moist or contaminated cooling air can come into direct contact with electrical or electronic components.

[0019] An interface on the engine intended for the cooling air inlet can advantageously be designed in such a way that the optional connection of a suction line is possible. The interface is advantageously designed in such a way that connection is easy, e.g., by snapping or snapping, in particular without the need for tools.

[0020] In a further advantageous embodiment, it is conceivable that an active element, for example a separate fan or a fan wheel, increases the flow of cooling air through the intake manifold and the cooling pot or the inner cooling air ducts or areas.

[0021] Advantageously, a separate small fan, e.g. a housing fan, can be placed outside the intake manifold inlet to force cooling air from the pressure-side environment through the inlet into the intake manifold in order to achieve a higher cooling air flow and thus a better cooling effect.

[0022] The outflow of the air has high velocities, so that the warm air of the fan's main flow is thrown downstream of the fan away from the fan, so that this warm air does not reach the inlet area of ​​the suction line and therefore cannot be sucked in there.

[0023] The method according to the invention solves the problem mentioned at the outset by the features of the further independent claim 18, wherein the method uses a device according to the invention and / or a fan according to the invention.

[0024] There are now various possibilities for advantageously embodying and developing the teaching of the present invention. For this purpose, reference is made, on the one hand, to the dependent claims and, on the other hand, to the following explanation of preferred embodiments of a cooling device according to the invention with reference to the drawing. In conjunction with the explanation of the preferred embodiments of the invention with reference to the drawing, generally preferred embodiments and developments of the teaching are also explained. The drawing shows:

[0025] Fig. 1 shows a perspective view from the downstream side of a fan with a supporting guide unit with housing and guide vanes and with a cooling device according to the invention,

[0026] Fig. 2 in perspective view from the inflow side the fan with cooling device according to Fig. 1

[0027] Fig. 3 in a side view and in section on a plane through the axis of the fan with cooling device according to Fig. 1 and 2,

[0028] Fig. 3a a detailed view from Fig. 3 in the area of ​​the cooling pot of the cooling device,

[0029] Fig. 4 in a flat axial plan view from the downstream side, the fan with cooling device from Fig. 1 to 3,

[0030] Fig. 4a shows a planar axial plan view of the fan with cooling device from Figs. 1 to 4, seen from the downstream side, whereby, in contrast to Fig. 4, the downstream cover of the cooling pot is not shown, whereby elements in the cooling pot become visible, Fig. 5 shows a perspective view of a one-piece component of a cooling device, which comprises the elements of the cover of the cooling pot towards the pressure side and the suction line,

[0031] Fig. 5a shows a perspective view of a one-piece component of a cooling device comprising the elements of the cover of the cooling pot towards the pressure side and a connection of a suction line,

[0032] Fig. 6 shows a perspective view of an air handling unit with two fans sucking in air via heat exchangers, each with a supporting guide unit and cooling device, seen from the outflow side of the fans,

[0033] Fig. 7 shows a perspective view from the downstream side of a fan with a supporting guide unit with housing and guide vanes and with a further embodiment of a cooling device according to the invention with an axially directed suction pipe,

[0034] Fig. 8 in a side view and in section on a plane through the axis of the fan with cooling device according to Fig. 7,

[0035] Fig. 9 in a side view and in section on a plane through the axis of a fan with a supporting guide unit with housing and guide vanes and with a further embodiment of a cooling device according to the invention with an axially directed suction pipe with a variable equivalent flow cross-section, and

[0036] Fig. 10 is a diagram illustrating, by way of example, the relative improvement achieved experimentally in a test setup, i.e., the reduction in the temperature of a thermally critical electronic component as a function of the temperature difference between the fan main flow and the pressure-side environment for two different diameters of a suction line. Fig. 1 shows, in a perspective view from the downstream side, a fan 57 of axial design with a supporting guide vane unit 1 with an exemplary embodiment of a cooling device 40 according to the invention, which in particular has a cooling pot 8, a suction line 12, and a cooling pot cover 43. The guide vane unit 1 consists in particular of a housing 2, an intermediate ring 5, a hub ring 4, inner guide vanes 11 extending between the hub ring 4 and the intermediate ring 5, and strut vanes 3 extending between the intermediate ring 5 and the housing 2 or its diffuser region 10.The guide vane unit 1 is preferably manufactured in one piece using a casting process, preferably by plastic injection molding. The hub ring 4 also forms the outer ring, the outer wall, of the cooling pot 8.

[0037] The housing 2 defines the outer boundary of a fan flow extending within the housing 2, also referred to as the main fan flow. The housing 2 consists of various sections, initially an inlet nozzle 9, then an advantageously cylindrical section 29, within which the impeller 19 with its blades 22 is arranged, and a diffuser section 10, to which strut blades 3 are attached.

[0038] Downstream of the impeller 19 within the housing 2, an inner guide vane device is arranged, consisting in particular of aerodynamically effective inner guide vanes 11, which extend between the hub ring 4 and the intermediate ring 5. Due to the aerodynamic effect of the inner guide vanes 11 in interaction with the intermediate ring 5 and the hub ring 4, the static efficiency and the air performance, especially the static pressure increase, of the fan 57 are particularly high at a specific flow rate, i.e., the volume flow of the main fan flow sucked in by the fan 57 through its inlet nozzle 9.

[0039] The hub ring 4 complements the radially outer wall of a cooling pot 8 of the cooling device 40. The cover 43 largely closes off the cooling pot 8 from the main fan flow, so that the cooling pot 8 only has openings or flow connections to the main fan flow on its front side, which is not visible here and faces the impeller 19 or the inlet nozzle 9 (see also Fig. 3, 3a). Connected to the cooling pot 8 is the cooling air line 12 or suction line 12. This runs approximately transversely to the main fan flow and shields an internal flow of cooling air from the main fan flow. With regard to the flow of cooling air, it connects the interior of the cooling pot 8 with an area assigned to the fan pressure side (see also Fig. 6) radially outside the fan 57 or the guide vane 1 or its housing 2, for which purpose the suction line 12 traverses the wall of the housing 2.

[0040] It is also conceivable that it is guided past the downstream end of the housing 2 on the downstream side. During operation of the fan 57, which increases the total pressure or the static pressure of the main fan flow it conveys from the suction side assigned to the inlet nozzle 9 to the pressure side assigned to the outflow end of the diffuser 10, air now flows radially outwards into the cooling device 40 or its suction line 12 as a result of the pressure gradient generated by the fan 57 and thus through the suction line 12 into the cooling pot 8, in which an electric motor to be cooled is arranged. This air then flows out of the cooling pot 8 through openings towards the impeller 19 of the fan 57 and mixes with the main fan flow. In many typical systems (see also Fig.6) The temperature level of the fan's main flow, which is sucked in through the inlet nozzle 9, is considerably higher than the temperature level of the ambient air surrounding the fan outside its housing 2 on its downstream or pressure side, which often corresponds to the free atmospheric environment or a large, moderately temperate space into which the fan blows the fan's main flow. This means that the cooling air sucked in by the suction line 12 and subsequently flowing into the cooling pot 8 has a considerably lower temperature level than the fan's main flow. The electric motor arranged within the cooling pot 8 is thus at least partially located in an environment with a lower temperature than, for example, the impeller 19 of the fan 57 with its blades 22, which are exposed to the high temperature level of the fan's main flow. This can significantly facilitate or improve the cooling of this electric motor.

[0041] The outer strut vanes 3 are provided to hold the motor 34 with the impeller 19 as shown in Fig. 3, as well as the inner guide vane device to the outer housing 2. These have at most a subordinate fluidic function and serve primarily to attach the inner guide vane device and thus the motor 34 and the impeller 19 to the outer housing 2. They are designed to be noise-efficient, so that their presence during operation of the fan 57 generates little or no additional noise. Overall, within the housing 2 in the axial region of the diffuser 10, viewed in the span direction (from the hub ring 4 to the diffuser 10), two different flow areas are formed: an outer flow area 6 between the intermediate ring 5 and the diffuser wall 10 of the housing 2, and an inner flow area 7 between the hub ring 4 and the intermediate ring 5.

[0042] The inner flow area 7 has the supporting inner guide elements 11, which have a fluidic function and, for example, reduce flow swirl, cause a build-up of static pressure, avoid or reduce hub backflow and, due to their radially inner position, generate only little noise.

[0043] The outer flow area 6 has the supporting strut vanes 3, 6 in the exemplary embodiment, advantageously 4-8, distributed around the circumference. These vanes are designed for noise reduction. On the supporting guide vane unit 1, flanges are integrally formed on the edge areas of the housing 2 on the inflow and outflow sides, which advantageously feature various fastening devices.

[0044] At this point, it should be noted that cooling devices according to the invention can also be used in fans with guide vanes without an intermediate ring, in which the guide vanes extend continuously from a hub ring, which advantageously also serves as the outer wall of the cooling pot, to the housing. Particularly in such embodiments, the intake pipe 12 can advantageously also extend following a guide vane, or be fully or partially integrated into a guide vane, or at least partially utilize the respective guide vane as a wall or be attached to it. Multiple intake pipes can also be used, for example, with multiple guide vanes.

[0045] Cooling devices according to the invention can also be used with fans without guide vanes, in which case suspension struts must be provided for connecting the motor to the housing, which can be used to attach the intake manifold(s). Even more advantageously, the intake manifold(s) can be integrated into suspension struts. The only essential requirement is that cooler air is directed from the pressure-side environment into a cooling pot without mixing with the main fan flow, or at most only very slightly. In other embodiments, intake manifolds can simply be designed as hoses, pipes, flexible conduits, or the like, for example also in the form of commercially available standard products. The key requirement is that the inner diameter of the intake line is sufficiently large to convey sufficient cooling air into the cooling pot.

[0046] For example, the inner diameter (the equivalent hydraulic diameter for non-circular cross-sections) can be greater than 5%, preferably greater than 10%, of the fan impeller diameter. When using multiple suction pipes, the equivalent hydraulic diameter of the total cross-section of all suction pipes serves as the design basis. On the other hand, the suction pipe should not represent an excessive obstruction to the main fan flow, to which it runs perpendicular. Therefore, integrated or combined designs with guide vanes or suspension struts, or elongated, non-circular cross-sectional shapes, or the use of multiple slender suction pipes, can be particularly advantageous.

[0047] On the upstream flange, fastening provisions 20 are provided for fastening the downstream guide unit 1 and thus the fan 57 to a higher-level device or system, just as fastening provisions 21 are provided on the downstream flange for fastening the downstream guide unit 1 to a higher-level device or system, such as a cooling device (chiller) or a heat pump.

[0048] Furthermore, fastening provisions 25 for a contact protection grille are provided on the downstream flange, which can also be provided similarly on the upstream flange. The contact protection grilles can be screwed countersunk into the area 25 so that they do not protrude axially beyond the downstream guide unit 1, which results in good handling and stackability of the fans 57. For this purpose, the cooling device 40 according to the invention, comprising in particular the suction line 12, the cooling pot 8 with the cooling pot cover 43, is located in its entirety axially between the upstream and downstream flanges of the downstream guide unit 1 of the fan 57.

[0049] Fig. 2 shows a perspective view from the inflow side of the fan 57 with cooling device 40 according to Fig. 1. In addition and supplementing the illustration according to Fig. 1, the impeller 19 with its blades 22 attached as one piece to a hub 31 can be seen more clearly. A hub cap 37 is attached to the hub 31 of the impeller 22, advantageously latched in place with locking hooks. The hub cap 37, in interaction with the hub 37, ensures a streamlined contour in the hub area of ​​the impeller 19, which is advantageous for high efficiency and low noise levels. The rotor 35 of the motor 34, here advantageously an electric external rotor motor, can be seen within the hub cap 37, which has a large opening in a radially inner area. This design of the hub cover 37 with an inner opening ensures good cooling of the rotor 35 of the motor 34, at least with the air of the main fan flow.It is also conceivable to design impeller hubs that are closed towards the inflow side in order to achieve a flow around the rotor 35, completely or partially, with the cooler air of the cooling device 40, which flows in through a suction line 12.

[0050] When the fan 57 is in operation, the impeller 19, driven by the rotor 35 of the motor 34 to which it is attached, rotates in the direction of rotation 32, here approximately clockwise. As a result, the fan 57 conveys a conveying medium, frequently air, in the form of the main fan flow from the inflow side visible here in the foreground in the flow direction through the axial areas of the inlet nozzle 9, impeller area 29 and diffuser 10 to the outflow side axially opposite the inflow side. In particular, energy is transferred to the conveying medium flow thus conveyed, which is measurable in the form of an increase in pressure, in particular an increase in total pressure and / or an increase in static pressure. Downstream of the impeller, the conveying medium flow is divided into two main components: one component that flows through the outer flow area 6 and a second component that flows through the inner flow area 7.

[0051] The impeller 19 with its blades 22 imposes a significant circumferential component in the flow velocity on the main fan flow, which is present at least immediately after the main fan flow has passed through the impeller 19. These circumferential velocities inevitably create a static negative pressure in the areas close to the axis compared to the areas far from the axis and in particular to the area on the housing 2. The static pressure on the housing 2 corresponds, at the outlet of the main fan flow from the diffuser 10 or at the downstream end of the housing 2, approximately to the ambient pressure of the pressure-side environment into which the outer end of the suction pipe 12 (Fig.1) opens.This means that the pressure level at the outer end of the intake manifold 12 is higher than the pressure level in the cooling pot 8, which is arranged close to the axis and is fluidly connected to the main fan flow, which inevitably leads to air flowing from the outside to the inside through the intake manifold 12 into the cooling pot 8. In many applications, this air has a lower temperature level than the main fan flow, which is why its use for cooling, for example, the electric motor 34 within the cooling pot 8 is particularly advantageous. In the exemplary embodiment, the cooling air flows out of the cooling pot 8 in an area between the cooling pot 8 and the hub 31 of the impeller 19 after flowing through the cooling pot 8, where it initially flows past the main cooling system of the electric motor 34 with its stator cooling fins 50 integrated into the stator 36, where it contributes significantly to improved cooling of the electric motor 34.

[0052] Fig. 3 shows a side view and a section through the axis of the fan 57 with cooling device 40 according to Figs. 1 and 2, wherein the motor 34 and the impeller 19 are not shown in section. Fig. 3a is a detailed view in the area of ​​the cooling pot 8, which is delimited radially on the outside by the hub ring 4 and is part of the cooling device 40. In addition to the relevant figures, the contour of the hub cap 37, which is designed to be aerodynamically favorable, rounded and tangentially continuous to the hub 31 of the impeller 19 and is attached in the area of ​​the hub of the impeller 19, can also be clearly seen here. The impeller 19 with its hub 31 and vanes 22 is fastened to the rotor 35 (see Fig. 2) of the motor 34, wherein a small radial distance is formed and a flow gap is present between the impeller vanes 22 with the winglets 38 and the impeller area 29 of the housing 2, in which the impeller 19 is approximately arranged as seen in the axial direction.

[0053] The motor 34, consisting of stator 36 and rotor 35, is arranged with its stator 36 within the cooling pot 8. The stator 36, with the electronics pot 13 integrated therein, is fastened to the front flange 54 of the cooling pot 8, which also serves as the motor mounting flange 59. The motor 34, in conjunction with the front flange 54, thus limits the cooling pot 8 towards the rotor side of the motor 34 or towards the inflow side of the main fan flow, which is on the right in the illustration shown. However, the cooling pot 8 is not completely sealed on this side, but cooling air can flow out to this rotor side through cooling openings 42. Towards the downflow side of the main fan flow, which is on the left in this illustration, the cooling pot 8 is largely sealed by the cooling pot cover 43.The suction line 12, which has an inlet 23 outside the housing 2 in the pressure-side connection space of the fan 57, which may also be a connection to another cooling flow line, opens inside into the cooling pot 8.

[0054] As a result of the pressure field generated by the fan 57 during its operation, air now flows from the pressure-side connection chamber into the cooling pot 8 at right angles to the main fan flow, then out through the cooling passages 42 towards the rotor side and ultimately mixes with the main fan flow, with which it is entrained and conveyed to the fan outlet side. On its flow path, this cooling air flow can now contribute in various ways to cooling the electric motor 34, here advantageously designed as an external rotor motor with integrated control electronics. Firstly, the stator 36 or the electronics housing 13 attached to or integrated therewith is cooled on its outer walls within the cooling pot 8 as a result of the lower temperature level in the cooling pot 8, i.e. heat can be effectively dissipated to the relatively cool cooling air (compared to the main fan flow).

[0055] It is also particularly advantageous in the exemplary embodiment that the cooling air is guided through cooling flow channels 41 defined by cooling flow guides 14 at a relatively high flow velocity close to the outer wall of the electronics housing 13 to be cooled, advantageous in particular in areas that are particularly easy to cool, in the vicinity of power electronics components inside the electronics housing 13 that dissipate a lot of heat, such as an output stage (IGBT), an input stage, or even opposite particularly temperature-sensitive components. This leads to particularly efficient cooling of these areas. As the cooling flow continues, cooling air flows out of the cooling pot 8 through one or more cooling passages 42 toward the rotor side.

[0056] In the exemplary embodiment, a rotor-side receiving area 46 is also provided, which represents an area that is also delimited radially outwards by the hub ring 4 and within which the flange 49 of the stator is arranged and fastened to the motor support flange 59 or flange 54 of the cooling pot 8. The stator cooling fins 50, which represent a significant heat-dissipating element of the main cooling system of the motor 34, are advantageously manufactured on the stator flange 49. The cooling fan impeller 51 attached to the rotor 35 sucks in cooling air at its radially inner inflow area, which previously flows over the cooling fins 50 of the stator 36, and hurls this cooling air, which has already absorbed waste heat at the stator cooling fins 50, radially outwards, where it mixes with the main fan flow and is conveyed with it to the downstream side of the fan 57.In any case, with regard to the cooling device 40 according to the invention, the cooling air flowing from the cooling pot 8, after passing through at least one cooling passage 42, is introduced into the main cooling system of the engine 34 due to the operation of the main cooling system of the engine 34 and guided past the cooling fins 50, where it can absorb heat particularly effectively due to its still relatively low temperature level. In this respect, the cooling device 40 utilizes, among other things, the already provided main cooling system of the engine 34 by introducing particularly cool air there and significantly increasing the effect of the main cooling system without causing additional power consumption, noise generation, or the like.

[0057] To reinforce and stabilize the connection of the motor 34 to the supporting guide vane unit 1, into which the cooling pot 8 is advantageously integrated as a single piece, stiffening ribs 58 are also provided within the cooling pot 8. These reinforce the connection of the hub ring 4 of the supporting guide vane unit 1 to the mounting flange 59 for the motor 34, which also represents the flange of the cooling pot 8 or its rotor-side boundary.

[0058] It is conceivable to provide interchangeable inserts in the area within the hub ring 4, i.e., cooling pot 8, in the mold for manufacturing the supporting guide unit 1 with the cooling pot 8 of the cooling device 40 integrated therein, in order to realize various interfaces to different motors and / or various embodiments of the cooling device 40, which is manufactured here integrally with the supporting guide unit 1. In this case, in addition to the bolt circle for fastening the motors, for example, the axial screwing plane for the motor 34, i.e., the axial position of the cooling device flange / motor support flange 54, 59, within the cooling pot 8 can also vary. The presence or design of the cooling flow guides 14 can also vary and be adapted to the respective motor provided.

[0059] The stator 36 can be seen from the motor 34, which here is an external rotor motor and is further advantageously designed as an EC motor, advantageously with an integrated motor electronics housing 13. An electronics housing 13 is integrated on the stator 36. An electronics housing / electronics housing can also be attached to a stator as a separate component. The cooling device 40 promotes the heat dissipation of waste heat from the stator 36 of the motor 34 and, in the exemplary embodiment, in particular from its electronics housing 13, in particular by conveying cooling air, which is cooler than the main fan flow, into the area of ​​the motor 34 in the cooling pot 8 via the suction line 12 for cooling purposes, but also through the special flow design, in particular of the interior of the cooling pot 8. As a result, electromagnetically active components and electronic components are cooled better, and the motor 34 can operate at the same ambient orThe conveying medium temperature produces higher torques and thus higher performance.

[0060] In the exemplary embodiment, the cooling pot 8 is designed such that, without the cover 43, it can be demolded in its entirety, including the cooling flow guide 14, in one piece and without undercuts from a casting tool, in particular from a plastic injection molding tool. This includes two shaping tool parts that are demolded from the component in the axial direction of the component, one of which is to the right in the view towards the fan inlet side and one to the left in the view towards the fan outlet side. As a result, the narrowest point between the cooling flow guide 14 and the stator 36 or electronics pot 13 is located approximately at the edge of the cooling flow guide 14 facing away from the stator flange 49. This is particularly advantageous for the economical manufacture of the corresponding tool and for the economical production of the components (cooling devices 40) in mass production.

[0061] Fig. 4 shows, in axial plan view and viewed from the downstream side, the fan 57 with the cooling device 40 with cooling pot 8, which here is integrated into a supporting guide vane unit 1, according to Figs. 1 to 3. In addition to the explanations for Figs. 1 to 3, the course of the suction line 12 can be clearly seen, running transversely to the main fan flow, passing through the inner flow area 7 and the outer flow area 6. The suction line 12 approximately follows the course of an inner guide vane 11 and a strut vane 3 in order to minimize the blocking effect with respect to the main fan flow.

[0062] Suction lines 12 can also be attached to guide vanes, struts, or the like, or even manufactured completely or partially integrally with them, for example in the form of hollow guide vanes. The cable connections 44 on the cooling pot 8 can also be seen. This is because power supply cables and, if applicable, electrical control lines must be routed from the outside, from outside the fan 57 and its housing 2, into the cooling pot 8 to the electric motor 34 or its stator 36. It is also conceivable to route these electrical lines within a suction line 12 in order to eliminate the need for connections 44 and further separate openings on the outer housing 2 for the cables. With such an advantageous design, the electrical lines are also not exposed to the higher temperatures of the main fan flow.

[0063] Fig. 4a shows a planar axial top view from the downstream side of the fan 57 with cooling device 40 from Figs. 1 to 4, wherein, in contrast to Fig. 4, the downstream cover 43 of the cooling pot 8 is not shown here, whereby elements in the cooling pot 8 and also the stator 36 or the electronics housing 13 of the motor 34 are visible. The cooling flow guides 14 are clearly visible, which direct the cooling air at a relatively high flow velocity close to the outer walls of the electronics housing 13 to be cooled in order to be able to effectively absorb waste heat there before it exits the cooling pot 8 through the cooling air outlets 42 located behind it in the direction of the rotor or impeller 19. The motor 34 is fastened with its stator 36 to the motor support flange 59, which also forms the rotor-side boundary of the cooling pot 8, by means of fastening devices 18, preferably screws.

[0064] It should be noted that embodiments without a cooling flow guide 14 are also conceivable. However, the design of a cooling flow guide 14 and thus a cooling flow channel 41 (Fig. 3a) with, as viewed along its center line in section, at least in some areas a very small distance from the outer wall of the stator 36 or the electronics housing 13 is particularly advantageous. However, the design of at least one cooling passage 42 in the axial region of the cooling housing flange 54 is crucial in order to achieve the described flow through the cooling housing 8 in interaction with the electric motor 34 during operation of the fan 57.

[0065] Fig. 5 shows a perspective view of an embodiment of a one-piece component of a cooling device, which comprises the elements of the cover 43 of a cooling pot towards the downstream side of a fan (cf. Figs. 1-4) and a suction line 12. The cover 43 essentially consists of a rather flat, axially closing region 45 and a side region 47 to which the suction pipe 12 is attached. The side region 47 is advantageously designed to complement a corresponding recess on a hub ring of a cooling pot, so that overall, in the assembled state, the cooling pot forms a region closed off from the downstream side of the fan (with the exception of the suction pipe 12). The illustrated component can advantageously be manufactured using plastic injection molding, wherein the interior region of the suction pipe 12 can then be formed using a water or air displacement process in the injection molding process.

[0066] Fig. 5a shows a perspective view of a one-piece component of a cooling device, which comprises the elements of the cover 43 of the cooling pot towards the downstream side of a fan (cf. Fig. 1-4) and a connection 63 of a suction line. The component shown does not have an integrated suction pipe, but rather a connection piece 63 for a suction line, for example a suction hose. For example, all kinds of commercially available flexible hoses can be connected, in particular also empty cable conduits, which are used, for example, when laying cables in floors or in the ground. It is important to select a sufficient flow diameter for the suction pipe and thus also for the connection piece 63.Thus, the narrowest effective cross-section for the cooling flow in the area of ​​the suction lines (in the case of several, in total across all suction lines) should advantageously not be significantly smaller than the narrowest effective flow cross-section in the further flow path up to the outlet from the cooling pot (cf. Fig 3, 3a).

[0067] Fig. 6 shows a perspective view from the outflow side of the two fans 57 of an air-conditioning device 64 with two fans 57 sucking in air via heat exchangers 65, each with a supporting downstream guide unit 1 and a cooling device 40. In the exemplary embodiment, a device with V-shaped heat exchangers 65 and two fans 57, each with a cooling device 40, is shown.

[0068] During operation, fans 57 draw ambient air through heat exchangers 65 into an interior of the unit 64 formed by unit walls 66 and nozzle plate 56. This air is warmed or heated while simultaneously extracting heat from the heat exchangers 65 or a coolant circulating therein. The heat is transferred to the heat exchanger via a coolant circuit with distribution pipes 68 and connections 67, and thus subsequently to the ambient air drawn into the unit's interior by fans 57. Thus, the main flow through fans 57, which draw in warm or hot air from the interior of the unit 64, is characterized by high fluid temperatures.

[0069] However, due to the operation of the cooling devices 40, the electric motor of the fans is now at least partially cooled by the cooler ambient air. This cooler ambient air is drawn through the inlets 23 into the intake lines 12 without being heated by the heat exchangers and then reaches a region close to the engine, where it serves to cool the engine. In this respect, the intake lines 12 can be viewed as a bypass for the heat exchanger flow, as they direct cooler ambient air directly, without flowing through the heat exchanger, into a region close to the engine, where it contributes to improved cooling.

[0070] There it acts, as described with reference to the preferred embodiment shown in Fig. 1-4, and significantly improves the cooling of the installed electric motors. In an astonishing and seemingly simple manner, the motors or fans 57 can be operated at very high conveying medium temperatures without the motors overheating and thus having a reduced service life. This enables a particularly high cooling capacity or cooling capacity density of such ventilation devices (e.g., cooling devices). It is advantageous if the air of the main fan flow exiting the fans 57 at their outlet, which has a rather high temperature level, has rather high speeds so that it is thrown away from the fans 57, for example in a type of jet flowing away from the fans 57.This prevents already heated air from entering the inlets 23 of the suction lines 12 and thus the cooling devices 40, which would severely impair the effectiveness of the cooling devices 40. This type of favorable outflow behavior, i.e., the avoidance of a so-called thermal short circuit, can be achieved by fans with guide vanes, such as in the embodiment according to Figures 1 to 4. Furthermore, the avoidance of a thermal short circuit is also of interest with regard to the effectiveness of the heat exchangers 65. It is also conceivable to connect further lines to the suction lines 12 at the inlets 23, which would then be used as connections, and to draw in air at locations where sufficient cool air is guaranteed to be present.

[0071] Fig. 7 shows a perspective view from the downstream side of a fan 57 with a supporting guide unit 1 with a housing 2 and guide or strut blades 3, 11 and with a further embodiment of a cooling device 40 according to the invention with an axially aligned suction pipe 12. The structure of the fan 57 with impeller 19, motor 34 and supporting guide unit

[0072] 1 including cooling pot 8 and its design in its interior is comparable to the fan according to Figures 1 to 4, which is why reference can be made to the corresponding figure descriptions for the description of the corresponding features. However, the cooling system 40 has a modified design. For example, no cover is provided on the cooling pot 8 (see also Figure 8), but rather the cooling pot 8 is open towards the pressure-side discharge environment with respect to the main fan flow. The suction pipe 12 connects axially to the cooling pot 8 over the entire open cross-section of the cooling pot 8 and projects axially beyond the supporting guide vane unit 1 or the housing.

[0073] 2 of the fan 57, into the pressure-side environment of the fan. The inner diameter of the suction pipe 12 corresponds approximately to the inner diameter of the cooling pot 8. It is important that the suction pipe 12 connects tightly to the cooling pot 8 without major leaks, which also requires sealing of those areas where the electrical cable guides or the electrical connections 44 for the motor cables are led radially outward from the cooling pot 8. Appropriate sealing designs can, for example, be integrated into the suction pipe 12. In this embodiment, the suction pipe 12 does not run transversely to the main fan flow, but rather approximately parallel to the main axial conveying direction of the main fan flow through the fan 57.

[0074] Cooler air from the pressure-side environment can flow into the intake pipe 12 at the open end and, in a known manner, into the cooling pot 8, where it can exert its enhanced cooling effect. Backflow can regularly occur in areas on the pressure side of an axial fan and near the imaginary extension of the fan axis, at least when considering the flow conditions a little downstream of the fan on the pressure side. This is due to the fact that the main fan flow, after exiting the housing 2, has a radial outward component and bursts open, creating a vortex system that induces backflowing fluid in an inner region near the axis downstream of the fan 57. Such backflow regions cause cooler air from the pressure-side environment to flow toward the fan 57 in a region near the axis.Due to the design of the suction pipe 12 shown, this cooler air is sucked in by the suction pipe and guided therein to the cooling pot 8 and its front cooling passages 42 (see Fig. 8), due to the pressure differences built up by the fan.

[0075] Fig. 8 shows a side view and a section through the axis of the fan 57 with cooling device 40 according to Fig. 7. In addition to Fig. 7, the connection area 30 of the suction pipe 12 to the cooling pot 8 can be seen more clearly. Various possibilities for how the connection can be made are conceivable, for example by screwing with appropriate provisions on the cooling pot 8 and / or suction pipe 12. Clamping or a connection with locking hooks or the like are also conceivable, as are adhesive connections or a connection using a method similar to a bayonet connection. Also expressly mentioned is the possibility of the suction pipe 12 being manufactured integrally and in one piece with the cooling pot 8.It is essential that a suction pipe 12, which does not run transversely to the main fan flow, but in a region close to the axis approximately parallel to the main conveying direction, projects axially beyond the flow outlet of the main fan flow, formed in particular by the outlet from the housing 2, by at least 5% of the diameter of the impeller 19 of the fan 57, advantageously by at least 20%. For particularly long suction pipes of a similar design, with a horizontal structure (which means the conveying direction is horizontal), it may be advantageous to additionally fasten the suction pipe directly to the outer housing 2 near the flow outlet, for example with at least one wire, cord, rope, or similar.

[0076] With such fans, it is often necessary to install an intrusion guard (protective grille) to protect against possible intrusion from the pressure side of the fan. Suitable contact guards are often attached to the supporting guide vane unit 1 or to a housing 2 on the outlet side of fans. Advantageously, a contact guard has an opening inside through which the intake pipe protrudes axially. This is because there is no danger radially inside the intake pipe 12 due to an intrusion, as there is no open access to rotating components. Particularly advantageously, a intake pipe 12 of a similar design can also be integrated into a contact guard as a single piece, for example as a welded construction or as an injection-molded one-piece component.

[0077] The largely leak-free connection of the intake pipe 12 to the cooling pot 8 at the connection point 30 is important. In Fig. 8, it can be seen in the area of ​​the cable connections 44 that a particular challenge may arise in this regard. Special components may have to be attached to seal this area if they cannot be advantageously integrated into the intake pipe 12 or the cooling pot 8. In general, it is conceivable to provide a sealing component at the interface 30 between the intake pipe 12 and the cooling pot 8, for example a rubber seal or the like. In an embodiment according to Figs. 7 and 8 or also Fig. 9, it is conceivable that at least some of the air from the main fan flow is also sucked in at the open end of the intake line 12, i.e. a mixture of the cooler air from the pressure-side environment and the main fan flow.

[0078] The greater the proportion of air in the fan's main flow with a higher temperature level, the more adversely this affects the cooling effect of the cooling system according to the invention. To counteract this and draw in the highest possible proportion of cool air from the pressure-side environment, the intake pipe can be designed to extend as far as possible into the pressure-side area, for example, axially by at least 20% of the impeller diameter beyond the outlet from the casing.

[0079] Fig. 9 shows a side view and a section through the axis of a fan 57 with a supporting guide vane unit 1 with a housing 2 and guide vanes or strut blades 11, 3 and with a further embodiment of a cooling device 40 according to the invention. This embodiment of the cooling system 40 also has, similar to the embodiment according to Figs. 7 and 8, an axially directed suction pipe 12 which, at a connection point 30, is axially directly connected to the cooling pot 8, which here is open to the axial pressure-side direction, and projects axially beyond the housing 2 into the pressure-side environment.

[0080] The intake manifold 12 has a variable equivalent flow cross-section over its length; in particular, the diameter D1 at the inlet 40 into the intake manifold 12, at its free end projecting into the pressure-side environment, is smaller in this embodiment than the diameter D2 at the connection point 30 to the cooling pot 8. The flow cross-section of the intake manifold 12 here corresponds approximately to a circular cross-section with a variable diameter, but can also have other cross-sectional shapes deviating from the circular shape, for example towards the open end 40, which is why the hydraulically equivalent diameters are then used as diameters D1, D2 for dimensioning.

[0081] In other embodiments, the diameter D1 at the inlet 40 into the intake manifold 12 can also be larger than the diameter D2 at the connection 30 to the cooling pot 8. Advantageously, the cross-sectional profile and the ratio of the diameters D2 and D1 are designed such that the proportion of air from the warmer fan main flow that is sucked into the intake manifold 12 is as small as possible and the proportion of air from the cooler pressure-side environment that is sucked into the intake manifold 12 is as large as possible in order to achieve the best possible cooling effect of the cooling system according to the invention. These proportions can vary depending on the fan operating point, since the flow pattern of the fan main flow depends on the operating point. The ideal conditions can vary depending on the operating point for which the system is primarily to be designed.

[0082] Advantageously, a suction pipe 12 of an embodiment with axially aligned suction pipe 12 can be designed similarly to an embodiment of Figures 7-9 such that the efficiency and pressure stability of the fan increase as a result of the suction pipe 12, in particular if the equivalent diameter D1 at the inlet 40 into the suction pipe 12 is larger than the diameter D2 at the connection 30 to the cooling pot 8, advantageously by a factor of at least 2, and the outer wall of the suction pipe 12 is designed to be aerodynamically advantageous for the main fan flow.

[0083] An advantageous diameter D2 for the suction pipe 12 at the connection to the cooling pot 8 of an embodiment with axially aligned suction pipe 12 similar to an embodiment of Figures 7-9 is approximately 20%-45% of the outer diameter D of the fan impeller.

[0084] Fig. 10 shows a diagram illustrating the relative improvement, i.e., reduction, in the temperature of a thermally critical electronic component, measured experimentally in a test setup, as a function of the temperature difference between the fan main flow and the pressure-side environment for two different diameters of a suction line. The experimental setup was carried out using an embodiment similar to Figures 1-4, in which a suction line perpendicular to the fan main flow directs the cooler air from the pressure-side environment into a cooling pot. Various temperature differences ΔT between the fan main flow and the pressure-side environment were set on a test bench (ΔT=temperature (fan main flow) - temperature (pressure-side environment)).In addition, a reference measurement was carried out with the same fan under the same operating condition without the cooling system according to the invention, more precisely without the suction line and without the cover on the cooling pot.

[0085] The fan speed and operating point (displacement flow rate of the fan's main flow) were set constant for all tests. As a result of the tests, the steady-state temperature Teicooi (stationary temperature after a sufficiently long constant operating period with the cooling system according to the invention) was measured at a specific, thermally critical electronic component, in this case the IGBT or the output stage of the power electronics integrated in the motor. Since the corresponding steady-state temperature was also measured for the reference test without the cooling system according to the invention (referred to as TeiRef), an improvement resulting from the application of the cooling system according to the invention can be evaluated for TeiRef - Teicooi.

[0086] Going even further, if this improvement is related to the temperature difference ΔT between the fan main flow and the pressure-side environment, a thermal efficiency C|T of a cooling system according to the invention, which cools components to be cooled of a fan or its motor or its control electronics, which fan has a fan main flow with a higher temperature level than the pressure-side environment, by using the cooler air of the pressure-side environment, can be defined as: r|T=(TeiRef - Teicooi) / ΔT. This efficiency C|T describes how "efficiently" the temperature level of the cooler air on the pressure-side environment is used for cooling, for example, engine components or electronic components when the main flow is sucked in through the inlet nozzle of the fan and has a higher temperature level.Such an efficiency can be measured and considered equivalently for different locations or components of the fan, motor or control electronics at which the temperature is measured, and it varies depending on the component or location for the same structure.

[0087] In the experiment shown here, it was determined for the often critical temperature of the output stage of the power electronics, as a function of AT and the diameter of a suction line with a constant cross-section Di, shown here in dimensionless form ös=Di / D, related to the fan impeller diameter D. At this point, it should be mentioned that when quantitatively specifying Di or ös, the hydraulically equivalent diameter of the entire flow-through cross-section of the suction line(s) must be used for non-circular cross-sections of a suction line or when using several parallel suction lines.

[0088] The diagram clearly shows that for a relative diameter ös of the suction line of ös = 12% (relative to the impeller diameter D), a relatively constant thermal efficiency of C|T « 50% can be achieved with the cooling system according to the invention (solid line). For example, this can mean that if the pressure-side ambient temperature is 30 K lower than that of the main fan flow, the output stage is approximately 15 K cooler by using the cooling system according to the invention, which represents a significant improvement.

[0089] The diagram also shows the result achieved with an intake line with a relative diameter of ös = 8%, shown with a dashed line. Since less cool air can flow per unit of time through the intake line with the smaller flow cross-section to the cooling pot and / or this air is already preheated more significantly as it flows through the intake line, the thermal efficiency is also lower in this case. For the intake line with a relative diameter of ös = 8%, the thermal efficiency C|T is approximately C|T « 35%, although this varies slightly depending on the temperature difference ΔT, from approximately C|T = 31% at ΔT = 10K to approximately C|T = 38% at ΔT = 40K. Various measurement inaccuracies, including changes in the thermal output of the engine components and variable air densities, can also influence the result.The choice of the total flow cross-section of the one or more parallel suction lines depends not only on the thermal efficiency to be achieved in the cooling system. Suction lines with larger flow cross-sections can be more complex to manufacture, for example because several are used in parallel. If a suction line with a large cross-section is used, this suction line, at least if it runs perpendicular to the main flow, obstructs the main flow of the fan, which can, for example, lead to a loss of efficiency. This problem does not exist or is only minimal with axial suction lines that run approximately parallel to the main flow in the axial extension of the cooling pot, for example similar to the embodiments shown in Figs. 7-9, which is an advantage of cooling systems designed in this way.

[0090] For suction ducts that run perpendicular to the fan's main flow, selecting the relative hydraulically equivalent total flow diameter of the suction duct(s) in a range of approximately θ=5% to θ=20% has proven to be useful and advantageous. Given the potential for efficiency losses due to the obstruction of transverse suction ducts to the fan's main flow, integrating suction ducts into support struts or vanes is also a particularly advantageous option.

[0091] Another aspect is that suction lines should be thermally insulated as well as possible from the main fan flow, so that the cooling air preheats as little as possible as it flows through the suction line. Therefore, it is advantageous for the walls of suction lines to be made of plastic and have a thickness of at least approximately 2 mm, preferably 3 mm.

[0092] For the sake of completeness, it should be mentioned that a cooling system according to the invention is suitable for a wide variety of devices, as well as for various fans of various designs, e.g., axial fans with or without guide vanes, radial or diagonal fans with a spiral casing, or an axially conducting casing (duct). It is essential that, as a result of the pressure field created by the fan, cooler ambient air is advantageously directed from an environment associated with the fan pressure side through a suction line perpendicular to the fan's main flow to a cooling chamber in which an electric motor is fully or partially arranged, where it is specifically used to cool the electric motor.The presented technology is also explicitly claimed for the opposite case in terms of temperature distribution, where the temperature level of the main fan flow has very low temperatures and the motor is installed in an environment in a "cooling pot" that has higher ambient temperature levels.

[0093] With regard to further advantageous embodiments of the device according to the invention, reference is made to the general part of the description and the appended claims to avoid repetition. Finally, it should be expressly noted that the exemplary embodiments of the device according to the invention described above serve merely to explain the claimed teaching, but do not limit it to the exemplary embodiments.

[0094] List of reference symbols Supporting guide unit Housing of the guide unit Strut wings Hub ring, outer ring of the pot of the

[0095] Cooling device Intermediate ring of the guide unit or diffuser outer flow area inner flow area Cooling device pot Inlet nozzle outer diffuser wall inner guide element, guide vane Suction pipe, suction line of the cooling device Stator pot, electronics housing Cooling flow guidance Mounting provision for motor on the mounting flange balance bike Inflow-side fastening device for the downstream guide unit to the higher-level system Downstream fastening device for the guide unit to the higher-level system Blade of the impeller Inlet or connection of the suction pipe, the suction line Mounting provision for protective grille downstream Diameter DN of the pot of the cooling device

[0096] Area for a wheel

[0097] Connection of the suction pipe to the cooling pot hub of the impeller

[0098] Direction of rotation of the impeller

[0099] Motor

[0100] Motor rotor

[0101] Motor stator

[0102] hub cap

[0103] Winglets of the impeller wings

[0104] Cooling device

[0105] Cooling flow channel

[0106] Cooling passage in the area of ​​the mounting flange Cover of the cooling device pot Cable connections on the cooling device pot Axially closing area of ​​the cover Rotor-side receiving area within the hub ring Side area of ​​the cover for connecting the intake manifold

[0107] Stator flange Cooling fins on the stator Cooling fan on the rotor

[0108] Cable connections on the stator or electronics housing of the motor

[0109] Front flange or front wall of the cooling pot

[0110] Nozzle plate fan, axial fan

[0111] Stiffening ribs in the receiving area for the

[0112] Motor

[0113] Mounting flange for motor

[0114] Connection piece for suction pipe on the lid

[0115] Ventilation device

[0116] heat exchanger

[0117] Equipment wall

[0118] Connections for coolant circuit

[0119] Coolant distribution pipes

[0120] Equivalent inlet diameter D1 of the

[0121] intake manifold

[0122] Equivalent diameter D2 of the cooling pot

Claims

Claims 1. Device for cooling the electric motor of a fan with air, wherein the fan, during operation, generates a pressure difference between the inflow side and the electric motor and the outflow side, and wherein the pressure difference is used to direct cooler ambient air from the outflow side to the electric motor.

2. Device according to claim 1, characterized in that the cooling in its fluidic function is based exclusively on the flow-Zpressure field generated by the fan, using exclusively the flow drive inherent in the fan.

3. Device according to claim 1 or 2, characterized in that a suction line, preferably designed as a suction pipe, is provided, which connects a central region of the fan close to the motor with the pressure-side (downstream) environment of the fan, where a higher pressure level associated with the fan downstream side prevails than in the central region close to the motor, and a lower temperature level than in the main fan flow announced by the inlet nozzle, wherein at the inflow point into the suction line at least part of the air from a free environment with a lower temperature level is present.

4. Device according to one of claims 1 to 3, characterized in that a cooling pot is provided which surrounds the electric motor or its stator and / or its electronics housing, which cooling pot forms a region which is largely closed off at least towards the inflow side and radially outwards for an environment filled with cooling air which has a lower temperature level than the main fan flow, and which is preferably arranged in a region close to the axis.

5. Device according to one of claims 1 to 4, characterized in that within the electric motor or its electronics pot and / or its stator, one or more internal cooling air ducts or one or more internal Cooling air areas are formed through which the cooling air flows, where it can absorb waste heat from the engine.

6. Device according to claim 4 or 5, characterized in that the suction line, which is preferably designed as a suction pipe, fluidly connects the interior of the cooling pot or the inner cooling air duct(s) or the inner cooling air region(s) with the pressure-side (downstream) environment of the fan, where a higher pressure level associated with the fan downstream side prevails and a lower temperature level than in the main fan flow announced by the inlet nozzle, wherein at the inflow point into the suction line at least some air from a free environment with a lower temperature level is present.

7. Device according to one of claims 4 to 6, characterized in that the air used for cooling flows from an atmospheric environment or a free, moderately temperate space via the suction line into the cooling pot or into the inner cooling air duct or the inner cooling air regions.

8. Device according to one of claims 4 to 7, characterized in that the cooling pot or the inner cooling air duct(s) or the inner cooling air region(s) has openings towards the inflow side of the fan or towards the impeller or its hub, through which cooling air flows out of the cooling pot or the cooling air ducts or the cooling air regions to the front, i.e. towards the impeller hub.

9. Device according to one of claims 4 to 8, characterized in that the cooling flow flowing out of the cooling pot or the inner cooling air duct(s) or the inner cooling air region(s) flows into a main cooling system of the electric motor, in particular through heat-emitting cooling fins on a flange of the stator of the electric motor.

10. Device according to one of claims 4 to 9, characterized in that the cooling pot or the inner cooling air duct(s) or the inner cooling air region(s) are arranged near the axis or near the hub in a region downstream of an impeller in which the main fan flow has significant circumferential velocities, resulting in a pressure field that has significantly lower static pressure levels radially inside, i.e. close to the axis, than radially further out.

11. Device according to claim 10, characterized in that the pressure field has a significantly lower static pressure level than in the outer region of the housing, whereby cooling air flows through the suction pipe into the cooling pot and then flows out through openings on the cooling pot and mixes with the main fan flow.

12. Device according to one of claims 4 to 11, characterized in that the cooling pot and / or the suction line is integrated in one piece into a supporting structure for the motor and the impeller, preferably into a supporting guide unit, of the fan.

13. Device according to one of claims 4 to 12, characterized in that flow guides are formed in the cooling pot or in the inner cooling air duct(s) or in the inner cooling air region(s), which guide the cooling air at a relatively high speed and / or high turbulence close to a wall surface of an electronics housing or stator to be cooled.

14. Fan with a device according to one of claims 1 to 13.

15. Fan according to claim 14, characterized in that it sucks in air on its inlet side which has previously flowed through a heat exchanger in its flow path, whereby it has been heated or whereby its temperature has been increased.

16. A fan according to claim 15, the outflow of which has high velocities so that the warm air of the fan main flow is thrown downstream of the fan away from the fan so that no such warm air can be sucked in at the inlet of the suction duct.

17. Fan according to claim 15 or 16, characterized in that cool ambient air is sucked directly or indirectly into the heat exchanger, which is heated as it flows through the heat exchanger, wherein cool air from the same cooler environment with a rather higher pressure level compared to a flow area between heat exchanger and fan is guided through the suction line into a region close to the motor or near the axis, where it serves for better cooling, wherein the suction line represents a type of bypass in terms of flow technology parallel to the heat exchanger flow, which guides cool ambient air directly to the electric motor of the fan.

18. A method for cooling the electric motor of a fan with cool air using a device according to any one of claims 1 to 13 and / or for use with a fan according to any one of claims 14 to 17.

Images