Radiator fan of a motor vehicle

Abstract

Radiator fan (2) of a motor vehicle, in particular main fan, with a rotor (30) of an electric motor (14) frictionally connected to a hub (36), through which cooling air (52) is directed at least partially, wherein the cooling air (52) is guided in two air guide channels (42, 44) that are at least partially sealed against each other, wherein one of the two air guide channels (44) at least partially surrounds the other air guide channel (42) radially, and wherein the exit direction of the cooling air (52) guided in the radially inner air guide channel (42) from the radiator fan (2) essentially corresponds to the inlet direction into the electric motor (14).

Description

[0001] The invention relates to a radiator fan of a motor vehicle, in particular a main fan, with an electric motor.

[0002] Motor vehicles with an internal combustion engine generate considerable heat during operation. To maintain the operating temperature of the internal combustion engine and also for the operation of an air conditioning system, a liquid coolant is usually used, which in turn must be cooled. This is usually achieved by means of a radiator network exposed to the airstream, which exchanges heat with the coolant. For example, the coolant is guided into pipes incorporated into the radiator network. Since the airstream is normally insufficient for cooling, particularly at low vehicle speeds, it is known, for example from EP 1 621 773 A1, to use an electric fan to amplify the airstream.

[0003] In this case, the fan is positioned behind the radiator core in the direction of travel. The fan's impeller draws air through the radiator core and directs it to the combustion engine. If, in addition to the radiator core, there is a condenser core for an air conditioning system, the condenser core is typically positioned in front of the radiator core in the direction of travel.

[0004] The electric motor itself is cooled by cooling air, which is drawn into the electric motor through openings on the side facing away from the radiator core. After this cooling air flow has completely passed through the electric motor, it is redirected by the hub of the fan wheel and directed into the ambient air.

[0005] DE 10 2005 049 261 B3 discloses a cooling fan for a motor vehicle. This fan has an electric motor, with two air streams being guided through the electric motor.

[0006] An axial fan is known from DE 41 43 383 A1. This fan comprises an electric motor mounted in a pot-shaped hub. An air flow is guided between the motors.

[0007] EP 1 722 462 A1 discloses an electric machine. A non-magnetically active portion of a rotor has an opening for guiding air.

[0008] The invention is based on the object of providing an improved radiator fan of a motor vehicle and an electric motor which is in particular cooled comparatively efficiently.

[0009] With regard to the cooling fan, this object is achieved according to the invention by the features of claim 1. Advantageous further developments and refinements are the subject of the subclaims.

[0010] The radiator fan is a component of a motor vehicle and is used in particular to cool an internal combustion engine. For this purpose, airflow is channeled through a radiator network, whereby the airflow is amplified by the radiator fan or generated when the vehicle is stationary. The radiator fan comprises a fan wheel with a number of fan blades. The fan blades are connected to a central hub. The connection can be made using additional elements, such as screws, or via material. In particular, the fan wheel is made of a plastic and is manufactured as a single piece using an injection molding process. The fan wheel is rotated by an electric motor. For this purpose, the fan wheel is connected to a rotor of the motor via the central hub. For example, the electric motor is a brushless internal rotor and the rotor is thus arranged within a stator of the electric motor.

[0011] To cool components of the electric motor, such as the electronics or any windings of an electromagnet, cooling air, which is preferably taken from the environment, is directed through the electric motor, in particular also through the hub. The cooling air is directed at least partially by means of two air ducts. The two air ducts are sealed from one another at least in sections, so that cooling air guided in one of the two air ducts does not come into contact with the cooling air guided in the other air duct. Mixing preferably only occurs outside the electric motor. In particular, the seal is present in the area of ​​the outlet from the electric motor, and suitably the seal is pneumatic, so that different air pressures can be achieved in the two air ducts.

[0012] Because the cooling air is distributed between the two air ducts, it is possible to cool specific components of the electric motor using one of the air ducts. For example, one of the air ducts is used to cool the electromagnet(s) of the electric motor, while the other is used to cool any permanent magnets present in the electric motor. It is also conceivable for the cooling air guided in one of the air ducts to cool a stator of the electric motor, and the cooling air guided in the other to cool the rotor of the electric motor. Alternatively, or in combination with this, the cooling air guided in one of the two air ducts is applied to a surface of a component of the electric motor, while the other air duct passes through this component. In this way, the component is cooled both from the outside and from the inside.

[0013] One of the two air ducts surrounds the other air duct at least partially radially, i.e., in a radial direction relative to the rotor of the electric motor. Consequently, the distance of one of the two air ducts from the rotor's rotational axis is greater than the corresponding distance of the other air duct. Each of the two air ducts is essentially shaped like a circular segment, for example.

[0014] The radially outer air duct expediently surrounds the radially inner air duct essentially completely. This ensures efficient cooling of both a radially inner region of the electric motor and a radially outer region of the electric motor. Preferably, the cross-section of the air ducts perpendicular to the axis of rotation of the electric motor is essentially annular, with the cross-section of the inner air duct alternatively being circular. In particular, the two air ducts lie against one another and are separated from one another only by the seal. At least the distance between the two air ducts is comparatively small. In particular, the rings or the ring and the circle are concentric with one another, with the center point lying in particular on the axis of rotation.

[0015] For example, the cooling air guided in the radially inner air duct is directed, in the outlet region, essentially parallel to the direction of entry of the cooling air into the electric motor. Preferably, the cooling air is drawn through the electric motor by the electric motor from the side facing away from the cooling core, so that the cooling air exiting the inner air duct is directed toward the cooling core. This is particularly counter to the direction of any airflow that may be present.

[0016] For this purpose, the hub preferably has at least one opening into which the radially inner air duct opens. In particular, the opening is offset radially inward. In other words, the distance of the opening to the axis of rotation of the electric motor is less than, for example, half the radius of the hub. Preferably, the distance is equal to a quarter of the radius or less. For example, a number of openings, i.e. at least two openings, are introduced into the hub. In this way, the cooling air flowing through the inner air duct is comparatively little obstructed, which ensures that the cooling air passes quickly through the electric motor. Furthermore, the use of a number of openings instead of a single large opening increases the stability of the hub and at least partially prevents dirt from entering the electric motor.

[0017] The exit direction of the cooling air guided in the radially outer air duct is preferably the same as the airstream, i.e., the direction of the airstream that at least partially impacts the electric motor. This reduces the formation of turbulence when the exiting cooling air mixes with the existing airstream, which improves the acoustic properties of the cooling fan.

[0018] Alternatively, or in combination with this, the outlet direction is opposite to the direction of entry of the cooling air into the electric motor. If the cooling air guided in the radially inner air duct is guided out of the electric motor in the inlet direction, mixing of the cooling air outside the electric motor is comparatively minimal, so that the heated cooling air is cooled separately and any component of the motor vehicle located outside the electric motor and behind the electric motor in the inlet direction is not exposed to a comparatively hot and strong cooling air flow—namely, the cooling air from both air ducts.

[0019] The hub suitably surrounds the rotor at least partially radially, with a circumferential slot being formed between the two. In particular, the hub is pot-shaped, with the inner radius of the hub being larger than the outer radius of the rotor and in particular of the electric motor. Expediently, the radially outer air duct opens into the slot formed between the hub and the rotor. In this way, a comparatively wide outflow area is provided for the cooling air guided in the outer air duct, which leads to a comparatively high flow velocity of the cooling air through the electric motor. In particular, a deflection contour is formed within the hub, by means of which deflection contour the cooling air is deflected such that it is parallel to the direction of the airflow or opposite to the inlet direction.

[0020] In a suitable embodiment of the invention, the direction of entry of the cooling air into the electric motor is substantially parallel to the electric motor's rotational axis. This eliminates the need to provide space for the cooling air supply in the area of ​​the electric motor's magnetic structure, which could impede the propagation and interaction of the magnetic fields and thus reduce the efficiency of the electric motor.

[0021] For example, the electric motor includes a deflection device that directs the cooling air to the corresponding air duct. The deflection device is located within the electric motor. The deflection device is therefore enclosed by any housing of the electric motor. In particular, the deflection device is located between the rotor and any electronics of the electric motor. As a result, the electronics are exposed to the entire cooling air, which is then distributed between the two air ducts. This makes cooling the electronics, which are the most temperature-critical component of the electric motor, comparatively efficient.

[0022] Furthermore, the air is guided and in particular sucked into the electric motor through only one intake opening or a plurality of pneumatically connected inlet openings. If one of the openings is blocked due to dirt or the like, each of the air ducts is still filled with cooling air, which leads to efficient cooling of the electric motor despite the reduced cooling air supply. Due to its placement within the electric motor, the deflection device itself is not affected by any dirt, which is kept outside the electric motor in particular by means of a suitable design of the openings. In particular, the deflection device is designed such that the cooling air is distributed among the respective air ducts according to the desired cooling performance. In particular, the allocation of the cooling air by means of the deflection device is independent of the cross-section of the two air ducts.

[0023] The two air ducts are expediently parallel to each other in the area of ​​the rotor. This eliminates the need for a complicated design of the air ducts to achieve the pneumatic separation of the two, which also requires a comparatively large amount of space. This makes it possible to optimize the rotor's magnetic properties and thus increase the efficiency of the electric motor. In particular, the air ducts are also parallel to the rotor's axis of rotation. In other words, the air ducts are essentially straight in this area, which contributes to an increased cooling air velocity and thus enhances the cooling of the electric motor. Furthermore, the air ducts are parallel to each other and to the axis of rotation, simplifying the manufacture of the electric motor, as no complex structures for guiding the cooling air need to be incorporated into the electric motor.

[0024] For example, both air ducts are formed by recesses that lead through the rotor. In a particularly preferred alternative, however, only one of the air ducts is realized by a suitable configuration of the rotor, so that this air duct leads through the rotor. The remaining of the two air ducts is formed in the region of the rotor by means of the air gap provided between the rotor and the stator. In this way, design effort is reduced, and an existing electric motor can be adapted by incorporating the second air duct into the rotor and sealing it against the air gap formed between the rotor and stator.

[0025] The electric motor has two air ducts that are at least partially sealed off from one another, into which cooling air is directed when the electric motor is in operation. The air ducts run at least partially through the electric motor and are, in particular, pneumatically separated from one another, such that cooling air located in one of the two air ducts cannot reach the other of the two air ducts, even when there is a pressure difference between the two. Suitably, the two air ducts lead out of the electric motor separately from one another. In other words, the electric motor has at least two spatially separate areas that are not connected to one another, from which the cooling air flows.

[0026] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In the drawings: Fig. 1 schematically shows a cooling fan with an electric motor, Fig. 2 a first embodiment of the electric motor, and Fig. 3 a second embodiment of the electric motor.

[0027] Corresponding parts are provided with the same reference numerals in all figures.

[0028] In Fig. 1 shows a simplified schematic side view of a radiator fan 2 of a motor vehicle. The radiator fan 2 comprises a radiator core 4, through which a cooling pipe 6 is guided. Within the cooling pipe 6 is a coolant that is kept circulating by a pump (not shown here). The coolant is passed through an internal combustion engine 8 and heated by it, cooling the internal combustion engine 8. The heated coolant is passed again through the radiator core 4, which is exposed to a relative wind. The direction of the relative wind is along a relative wind direction 10, which essentially corresponds to the main direction of travel of the motor vehicle.

[0029] By means of a fan 12, which is arranged behind the radiator grille 4 in the direction of the airflow 10, the airflow is amplified or generated when the vehicle is stationary. This is achieved by means of an electric motor 14, which rotates a fan wheel 16. Furthermore, the airflow is directed to the internal combustion engine 8 by means of the fan wheel 16, which thus exposes the engine to the airflow from the outside. This leads to additional cooling of the internal combustion engine 8. The fan wheel 16 is arranged within a radiator frame 18, by means of which the airflow is directed. In the transition area between the frame 18 and the fan wheel 16 there are brushes or a specific contour, each of which prevents so-called leakage air between the two components. The electric motor 14 is attached to the frame 18 by means of struts 20. The struts 20 are manufactured in one piece with the frame 18, for example, using a plastic injection molding process.

[0030] In Fig. 2 shows a sectional view along a rotational axis 22 of the electric motor 14, which is parallel to the airflow direction 10, of the electric motor 14 arranged behind the cooling core 4 in the airflow direction 10. The electric motor 14 comprises a cylindrically shaped housing 24, within which a stator 26 and a rotor 30 mounted for rotation about a rotor axis 28 are arranged. Electronics 34 for energizing electromagnets of the stator 26 are arranged in a cover 32 closing the housing 24 on the side opposite the cooling core 4. On the side of the housing 24 facing the cooling core 4, the housing 24 is defined by a pot-shaped hub 36, to which blades (not shown) of the impeller 16 are attached. The housing 24 lies partially in the hub 36, with a circumferential slot 38 formed between the hub 36 and the housing 24.In other words, the inner diameter of the hub 36 is larger than the outer diameter of the housing 24. The width of the slot 38 is essentially constant.

[0031] The hub 36 is attached to the rotor 30 by means of a web 40 having a substantially hollow cylindrical shape. In the region of the hub 36, the web 40 pneumatically seals a radially inner air duct 42 from a radially outer air duct 44, which completely surrounds the radially inner air duct 42. The radially outer air duct 44 opens into the slot 38 and is partially formed by the air gap 26 existing between the stator 26 and the rotor 30. The radially inner air gap 42, however, is formed in the region of the stator 26 or the rotor 30 by recesses 48 made in the rotor 30, which are substantially parallel to the rotational axis 22 and to the air gap 46. The radially inner air duct 42 opens into openings 50 which are introduced in the region of the rotation axis 22 into the region of the hub 36 facing the radiator network 4.

[0032] When the cooling fan 2 is operated and thus the electric motor 14 is energized, both the rotor 30 and the hub 36 coupled thereto are set into a rotational movement about the rotation axis 22 with respect to the stator 26. By means of an intake device (not shown in detail) integrated into the hub 26, such as vanes or internal ribbing, cooling air 52 is sucked into the electric motor 14 from the side of the electric motor 14 facing away from the radiator core 4 through openings (not shown in detail) within the cover 32, wherein the inlet direction of the cooling air 52 is directed essentially opposite to the direction of the airflow 10. The cooling air 52 sweeps over the electronics 34 and thus cools it.

[0033] After the electronics 34, the cooling air encounters a deflection device 54, by means of which the essentially homogeneous flow of cooling air 52 is distributed between the two air ducts 42, 44. The portion of the cooling air 52 guided in the outer air duct 44 is directed through the air gap 46, where the facing surfaces of the rotor 30 and the stator 26 are cooled, and encounters the radially outer region of the hub 36. This portion of the cooling air 52 is deflected by the hub 36 and fed to the environment through the slot 38. The exit direction of the cooling air 52 is essentially parallel to the airflow direction 10.

[0034] The remaining portion of the cooling air 52 is guided through the recess 48 in the rotor 30. The air flow is directed parallel to the rotational axis 22 and cools the permanent magnets present in the rotor 30 to prevent demagnetization and a consequent loss of efficiency. After passing through the rotor 30, the portion of the cooling air 52 guided in the radially inner air duct 42 encounters the area between the hub 36 and the rotor 30, sealed by the web 40. From this area, the cooling air 52 escapes through the openings 50 toward the radiator core 4, counter to the airflow direction 10.

[0035] By means of a suitable design of the intake device, a lower air pressure is generated in the radially outer air duct 44 compared to the radially inner air duct 42, so that the flow velocity of the cooling air 52 in the radially outer air duct 44 is increased. The deflection device 54 also deflects the cooling air 52 in such a way that essentially two-thirds of the cooling air 52 flowing into the electric motor 14 is directed into the radially outer air duct 44. This enables comparatively efficient cooling of the electric motor 14, in particular of the stator 26, with the rotor 30 additionally being exposed to the cooling air 52 from the inside and not just its surface.

[0036] The Fig.The embodiment of the electric motor 14 shown in Figure 3 differs from the previous one essentially in the design of the radially outer air duct 44 and the hub 36. The hub 36 rests against the housing 24, so that the slot 38 is not present. The annular chamber formed by the hub 36, the rotor 30, and the stator 26, which represents a portion of the outer air duct 44, is opened by means of outlet slots 56 through which the cooling air 52 guided in the radially outer air duct 44 exits.

[0037] Due to the guidance of the cooling air 52 toward the radiator network 4, the cooling air 52 exiting the electric motor 14 is located in front of the fan blades of the fan wheel 16 in the direction of travel wind 10, by means of which a pressure difference is created between the areas surrounding the electric motor 14 in the direction of travel wind 10. In other words, the air pressure in the area where the cooling air 52 exits through the hub 36 is lower than in the area where the cooling air 52 enters through the cover 32. Consequently, the intake device that draws in the cooling air 52 through the air ducts 42, 44 can be omitted, which leads to a reduced expansion of the housing 24 and the hub 36 in the direction of travel wind 10.

[0038] Furthermore, the speed at which the cooling air 52 flows through the electric motor 14 is essentially determined solely by the pressure difference realized by the fan wheel 16, which, compared to internal ribbing of the hub 36, is relatively independent of speed or essentially constant during operation of the cooling fan 2. The pressure difference between the two air ducts 42, 44 is thus realized solely by the deflection device 54. Furthermore, due to the omission of the slot 38, the radial expansion of the electric motor 14 is smaller. As a result, a comparatively compact cooling fan 2 can be realized.

[0039] Another difference is represented by inlet openings 58 through which the cooling air 52 is guided through the cover 32 and the electronics 34 into the electric motor 14. This leads to a defined impact of the cooling air 52 on the deflection device 54, which facilitates a demand-based distribution of the cooling air 52 to the respective air ducts 42, 44.

[0040] The invention is not limited to the exemplary embodiments described above. Rather, other variants of the invention can also be derived therefrom by those skilled in the art without departing from the subject matter of the invention. In particular, all individual features described in connection with the individual exemplary embodiments can also be combined with one another in other ways without departing from the subject matter of the invention. List of reference symbols 2 cooling fans 4 Radiator core 6 Cooling pipe 8 Internal combustion engine 10 Wind direction 12 fans 14 Electric motor 16 Fan wheel 18 Radiator frame 20 struts 22 Rotation axis 24 housings 26 Stator 28 Rotor axis 30 rotors 32 lids 34 Electronics 36 Hub 38 slot 40 jetties 42 radial inner air duct 44 radial outer air duct 46 Air gap 48 recesses 50 opening 52 Cooling air 54 Deflection device 56 Exit slot 58 Entrance opening

Claims

[1] Radiator fan (2) of a motor vehicle, in particular a main fan, with a rotor (30) of an electric motor (14) which is non-positively connected to a hub (36) and through which cooling air (52) is at least partially directed, wherein the cooling air (52) is guided in two air guide channels (42, 44) which are at least partially sealed against one another, wherein one of the two air guide channels (44) at least partially radially surrounds the other air guide channel (42), and wherein the outlet direction of the cooling air (52) guided in the radially inner air guide channel (42) from the radiator fan (2) essentially corresponds to the inlet direction into the electric motor (14). [2] Cooling fan (2) according to claim 1, characterized by that one of the two air ducts (44) completely surrounds the other air duct (42) radially. [3] Cooling fan (2) according to claim 1 or 2, characterized bythat the hub (36) has at least one opening (50) into which the radially inner air guide channel (42) opens. [4] Cooling fan (2) according to one of claims 1 to 3, characterized by that the exit direction of the cooling air (52) guided in the radially outer air guide channel (44) from the electric motor (14) is substantially equal to a travel wind direction (10) and / or opposite to the entry direction. [5] Cooling fan (2) according to one of claims 1 to 4, characterized by that the hub (36) at least partially radially surrounds the rotor (30) to form a circumferential slot (38), wherein the radially outer air guide channel (44) opens into the slot (38). [6] Cooling fan (2) according to one of claims 1 to 5, characterized by that the inlet direction of the cooling air (52) is parallel to the rotation axis (22) of the rotor (30). [7] Cooling fan (2) according to one of claims 1 to 6, characterized bya deflection device (54) for allocating the cooling air (52) to the respective air duct (42, 44) after entering the electric motor (14). [8] Cooling fan (2) according to one of claims 1 to 7, characterized by that the two air guide channels (42, 44) in the region of the rotor (30) are parallel to each other, in particular parallel to the axis of rotation (22) of the rotor (30). [9] Cooling fan (2) according to one of claims 1 to 8, characterized by that one of the air guide channels (44) is formed at least partially between the rotor (30) and a stator (26) and the other of the two air guide channels (42) is formed within the rotor (30).

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