EP1892421B1 - Axial ventilator powered by electricity - Google Patents

Description

The invention relates to an axial fan with electric drive according to the preamble of claim 1, known by the WO 03/040570 A1 ,

The one by the WO 03/040570 A1 has become known axial fan is used in particular as a cooling fan for engine cooling in motor vehicles. The cooling fan, consisting of the axial fan and a driving electric motor, is arranged within a fan frame, which is located in the air flow direction behind a coolant radiator or a multi-heat exchanger existing cooling module. Due to the electromotive drive occur in the drive shaft of the motor torsional vibrations, so-called pendulum moments, which are transmitted to the fan and emitted as sound. Such a fan noise is perceived as unpleasant and is therefore undesirable. The known fan has an approximately cup-shaped hub, which consists of a substantially flat end face and a substantially cylindrical peripheral surface, are attached to which axial blades. The fan is rotatably connected via the end face of the hub with the drive shaft of the motor, wherein the compound is formed bendable soft in the hub area. This should allow a tilting movement between the axis of inertia of the fan and the axis of rotation. Due to the flexurally soft connection of the axial fan to the rotor of the electric drive, the axial fan should align with increasing speed in the direction of the axis of rotation. This is intended to reduce an unbalance moment. Incidentally, the known Axiallüfter torsionally rigidly connected to the motor shaft, so that emanating from the engine excitation frequencies are transmitted to the fan, resulting in the unwanted sound radiation.

By the GB 2 265 420 A was an electric blower, consisting of an axial fan and an electric motor, known, wherein the fan is connected via a vibration-damping hub with the motor shaft. The hub is preferably made of an elastomeric, torsional vibration absorbing plastic material which prevents the transmission of torsional vibrations to the fan. A disadvantage of the known fan arrangement is that the hub area is traversed by air - this affects the efficiency and performance of the fan.

By the DE 196 35 179 A1 an axial fan was known with electric drive, wherein between the drive shaft of the motor and fan hub a multi-arm driving element is arranged. In this case, the fan hub is attached to the outer ends of the radially arranged radially arranged arms by screw connections. The entrainment element is intended to reduce the moment of inertia of the fan and to prevent tumbling movements of the fan wheel. Torsional vibrations are not damped, but transmitted via the driving element on the fan.

By the DE 81 10 769 U1 An electric fan with a hub was known, which is connected via molded parts made of elastic material with the motor shaft. The molded plastic parts are intended to absorb the torsional vibrations emanating from the motor (pendulum moments or vibrations in the tangential direction) and thus reduce the fan noise. The disadvantage here are the majority of molded parts and an inaccurate centering of the hub relative to the motor shaft, so that imbalances, combined with a troubled run, can result.

The decoupling of torsional vibrations, which emanate from the electric motor with respect to a fan is also known in heating and / or air conditioning systems for motor vehicles Such fan wheels are designed as radial fan wheels, which suck in the air axially and on the periphery arranged radial vanes (blade ring) in the radial outward direction in a blower spiral promote. The radial impeller has a hub, which is connected on the one hand with the motor shaft of an electric motor and on the other hand via spokes, struts or a perforated support disc with the blade ring. For damping the torsional vibrations emanating from the engine, ie for decoupling the blade ring from the motor shaft, various measures have been proposed:

By the DE 29 39 385 C2 The applicant has been known a radial fan in which the blade ring is connected to the motor shaft via spokes, which form a bundle of parallel-connected springs. Thus, a detuning of the spring mass system is achieved, and resonant vibrations of the blade ring, excited by the motor shaft, are avoided.

Similar proposals for decoupling the torsional vibrations in radial impellers were by the EP 0 181 549 A1 as well as the US-A 4,639,193 known, wherein also an elastic region or an elastic member are provided between the fan ring and hub.

By the DE 199 05 075 C2 has been known for a motor vehicle heating or air conditioning a radial impeller in which in the hub, an elastically deformable, vibration damping material is arranged. This also achieves decoupling.

By the DE 43 17 712 C1 has been known an electric machine driven radial impeller with a support disc is known, which is fastened by bolts elastic against the hub. To decouple the torsional vibrations damping elements in the form of rubber bushings are provided on the bolts.

The WO 20041097226 A1 discloses a fan having an inner and an outer hub portion with a vibration damping member therebetween.

The JP 2002 242882 discloses a fan with hub and bearings.

It is an object of the present invention, in an axial fan of the type mentioned, the acoustic emission, which is emitted by the fan and excited by the electric motor to reduce.

This object is solved by the features of claim 1. Advantageous embodiments of the invention will become apparent from the dependent claims.

According to the invention, the connection between the axial fan and the electric motor is formed torsionally soft, d. H. the torque transmitting area between the motor shaft and Axialbeschaufelung is formed in the circumferential direction elastic or yielding. Thus, the advantage is achieved that emanating from the motor shaft exciter frequencies, which cause the fan noise from the fan, in particular the fan blades are decoupled. The unpleasant fan noise, which is emitted via the fan blades, does not occur due to this decoupling.

In the case of a pot-shaped hub, the essentially planar and closed end face can be formed so as to be torsionally soft, specifically by means of a reduced wall thickness. This is particularly easy to implement in terms of injection molding technology in plastic fans with a plastic hub. The reduced wall thickness may be formed annular or sector-like, wherein for stiffening the hub, in particular for achieving a sufficient bending stiffness radially extending ribs are provided on the hub, which can also be molded. These ribs on the inside of the hub simultaneously fulfill a cooling function for the electric drive motor.

In order to achieve torsional softness, the hub region can also be designed as an open spoked wheel, wherein the spaces between the individual spokes are sealed airtight by a film, in particular an adhesive film. Thus, an aerodynamically favorable shape of the hub is achieved, whereby the flow favors in the blade area of the fan and its efficiency is improved. The spokes are torsionally soft and sufficiently rigid.

The fan hub can be mounted directly on the motor shaft, z. B. pressed or via an injection-connected with the fan hub metal bush, which is pushed onto the motor shaft.

Alternatively, the fan hub relative to the motor shaft via a driving element, which has radially projecting arms for screwing with the Lüfternabe be secured. In the screw vibration-absorbing damping elements, in particular bushes are arranged made of an elastomeric material, so that a decoupling in the tangential direction is achieved.

Furthermore, it can be provided in the driving element, that the radially extending arms in turn yielding in the circumferential direction, d. H. are elastically formed. Also, the decoupling between the motor shaft and fan can be achieved in the circumferential direction.

Fig. 1

einen Axiallüfter mit Lüfterzarge,

Fig. 2

ein erstes Ausführungsbeispiel für einen erfindungsgemäßen Axial- lüfter,

Fig. 3

einen Teilschnitt durch den Axiallüfter gemäß Fig. 2,

Fig. 4

ein zweites Ausführungsbeispiel des erfindungsgemäßen Axiallüf- ters,

Fig. 5

einen vergrößerten Teilschnitt des Lüfters gemäß Fig. 4,

Fig. 5a

eine stärkere Vergrößerung des Teilschnittes gemäß Fig. 5,

Fig. 6

ein weiteres Ausführungsbeispiel der Erfindung mit elastischer An- kopplung über ein Mitnahmeelement und

Fig. 7

ein weiteres Ausführungsbeispiel des Mitnahmeelementes.

Embodiments of the invention are illustrated in the drawings and will be explained in more detail below. Show it

Fig. 1

an axial fan with fan cowl,

Fig. 2

A first embodiment of an axial fan according to the invention,

Fig. 3

a partial section through the axial fan according to Fig. 2 .

Fig. 4

A second embodiment of the axial fan according to the invention,

Fig. 5

an enlarged partial section of the fan according to Fig. 4 .

Fig. 5a

a greater enlargement of the partial section according to Fig. 5 .

Fig. 6

a further embodiment of the invention with elastic coupling via a driving element and

Fig. 7

a further embodiment of the driving element.

Fig. 1 shows a view of an axial fan 1, as seen in the air flow direction, and a fan frame 2 with a Zargenring 2a, in which the axial fan 1 rotates. The fan frame 2 is rectangular in shape and adapted to a heat exchanger, not shown, in particular a coolant radiator and attached thereto, preferably via laterally arranged fastening elements 2b. The coolant radiator, not shown, may also be part of a cooling module, consisting of further heat exchangers such as intercooler, refrigerant condenser and oil cooler, which are arranged in the front engine compartment of a motor vehicle. The axial fan 1 is driven by a not visible here electric motor, which is connected via fastening elements, in particular struts 3 with the fan frame 2. The axial fan 1 thus sucks through the coolant radiator or the cooling module, not shown, ambient air and thus cools the coolant of a coolant circuit, the charge air for an internal combustion engine and / or the refrigerant of a refrigerant circuit of an air conditioner. The axial fan 1 is, as will be explained in more detail below, decoupled in the direction of rotation relative to the driving electric motor, whereby a noise emission by the fan 1 is avoided.

Fig. 2 shows the fan 1 off Fig. 1 as a single item. The fan is designed as an axial fan 1, as a so-called sickle fan, and has crescent-shaped, ie in the direction of rotation curved fan blades 4 (hereinafter also called axial blades), a hub 5 and a shell 6. The fan blades may also be formed straight (in the radial direction) or with opposite curvature. The axial fan 1 with hub 5, axial blades 4 and sheath 6 is preferably formed integrally as a plastic injection molded part. The hub 5 is approximately cup-shaped and has a substantially planar end face 5 a, in which sector-shaped openings 7, evenly distributed over the circumference, are arranged. Between the openings 7 radially extending webs 8 are left. Through the openings or recesses 7, the hub portion 5a is formed rotatable or torsionally soft, ie, the end portion is resilient in the direction of rotation. However, since the hub 5, in particular its end face 5a should be closed for aerodynamic reasons, the recesses 7, what in Fig. 2 Not is represented covered by a film, in particular an adhesive film - the film transmits no torque.

Fig. 3 shows a partial section along the line III-III in Fig. 2 through the hub 5. The fan hub 5 is - as clearly visible in the sectional view - pot-shaped, ie at the substantially planar formed end portion 5a is followed by a slight rounding a substantially cylindrically shaped peripheral surface 5b, to which the fan blades 4 are sprayed. The fan hub 5 is pressed onto an only partially shown motor shaft 9 of an electric motor, not shown. The hub 5 is flowed in the direction of an arrow L from the air, and the drive motor, not shown, is located in the downstream region of the fan hub 5 - as well as from the above cited , generic document is known. The recesses 7 are covered airtight by an adhesive film 10, so that they can not be traversed by air This prevents a backflow (recirculation) of the air in the hub area. On the inside, that is, the side facing away from the air flow side of the end face 5a extending ribs 11 are arranged in the radial and axial directions, which cause a stiffening of the fan hub 5, in particular in the stimulus 5a. At the same time, the stiffening ribs 11 fulfill a cooling function by conveying cooling air in the direction of the electric motor, not shown. The illustrated hub 5 is thus closed in its stimulus area 5a and forms a smooth aerodynamic surface. On the other hand, the hub 5 is rotationally soft due to the recesses 7, so that the fan blades 4 are decoupled and can not be excited to noise-causing vibrations in the tangential direction. Nevertheless, due to the ribbing by the ribs 11, a sufficient bending stiffness of the hub 5 is ensured.

Fig. 4 shows as a further embodiment of the invention, an axial fan 12, in which only the hub 13 deviating from the embodiment according to FIGS. 2 and 3 is formed: it has an annular region 14 with reduced wall thickness.

Fig. 5 shows a section through the hub 13 corresponding to the sectional plane VV in Fig. 4 , It can be seen from the sectional view of the cup-shaped design of the hub 13 with a substantially planar end portion 13a and a substantially cylindrical peripheral portion 13b, however, can also - for fluidic reasons - slightly tapered. The end region 13a has the annular surface 14, in which the wall thickness of the hub 13, in particular the wall thickness of the stimulus region 13a, is reduced to the thickness of a membrane or skin. As a result of the reduced wall thickness in the annular region 14 results for the hub 13 a compliance in the circumferential direction with the consequence of a decoupling of exciter frequencies, which emanate from the motor shaft. Due to the thin skin 14, the fan hub 13 remains closed in the end region 13a, so that no air can pass through. On the inside of the hub 13 in turn ribs 15 are arranged, which extend in the radial and axial directions and thus ensure a sufficient flexural rigidity of the hub 13.

Fig. 5a shows the fan hub 13 accordingly Fig. 5 in a further enlarged view, rotatably connected to a motor shaft 16 which drives the hub 13. Between the motor shaft 16 and the end portion 13 a of the hub 13, a metal disc 17 is arranged, which on the one hand connected by injection molding with the hub portion 13 a and on the other hand rotatably mounted on the motor shaft 16. The hub 13 has, in particular in the end region 13a, a wall thickness s, which is significantly reduced in the annular region 14, so that a rotationally soft connection between the motor shaft 16 and the peripheral region 13b results with the fan blades. Measurements made by the Applicant have shown that this rotationally soft connection results in a significant reduction in fan noise compared with the prior art.

Fig. 6 shows a further embodiment of the invention, in which the axial fan, not shown here, is attached via a driving element 18 to the motor shaft 19 of an electric motor 20. The front view of the motor 20 shows three arranged on the circumference of the motor 20 mounting tabs 21, via which the motor 20 and with it the fan, not shown, is attached to a fan frame, not shown here. The entrainment member 18 has three star-shaped arms 18a, 18b, 18c, at the outer ends are not shown holes for receiving bolts. As far as the driving element 18 corresponds to the prior art, ie the aforementioned DE 196 35 179 A1 , The fan, not shown, is connected via decoupling elements, designed as elastic bushes 22 and recognizable in the left-hand sectional view, by means of the bolts with the driving element 18. By the elastic bushes 22, which as an elastic member act between the driving element 18 and the fan, a decoupling of the fan with respect to the motor shaft 19 is achieved.

Fig. 7 shows a further embodiment of the invention, similar to the embodiment according to Fig. 6 , wherein like reference numerals are used for the same parts. On the motor shaft 19 of the electric motor 20, a driving element 23 is rotatably disposed, which has three extending in the radial direction, circumferentially elastic arms 23a, 23b, 23c, at the ends of which are bores for receiving bolts. The fan, not shown, is connected by means of bolts, not shown, that is connected by a screw with the driving element 23. The decoupling takes place here by the resilience of the radial arms 23a, 23b, 23c in the circumferential direction - therefore, the elastic decoupling elements in the form of rubber bushings 22 according to Fig. 6 omitted in this embodiment.

Claims (7)

1. Axial blower (1, 12) comprising a hub (5, 13) for connecting the axial blower to an electrical drive motor (20), wherein the hub (5, 13) is substantially pot-shaped and comprises a front region (5a, 13a) and a substantially cylindrical circumferential region (5b, 13b),
   characterized in that the front region (13a) comprises an approximately annular region (14) having a reduced wall thickness, and the reduced wall thickness is designed as a diaphragm (14).
2. The axial blower according to claim 1, characterized in that recesses (7) are disposed in the front region (5a) and are covered by a film (10), preferably an adhesive film.
3. The axial blower according to one of the claims 1 to 2, characterized in that the front region (5a, 13a) comprises substantially radially extending braces or ribs (11, 15) on the side facing the drive motor.
4. The axial blower according to one of the preceding claims, characterized in that the axial blower (1, 12) is designed integral with the hub (5, 13), preferably as an injection-molded part.
5. The axial blower according to one of the preceding claims, characterized in that the electric drive motor (20) comprises a motor shaft (19) onto which a driving element (18, 23) comprising a plurality of radial arms (18a, 18b, 18c; 23a, 23b, 23c) is fastened, which is connected in a torsionally smooth manner via the radial arms to the front region of the hub.
6. The axial blower according to claim 5, characterized in that decoupling elements, in particular elastic and/or damping bushings (22) composed of an elastomeric material, are disposed between the radial arms (18a, 18b, 18c) and the front region.
7. The axial blower according to claim 5 or 6, characterized in that the radial arms (23a, 23b, 23c) are elastic and resilient in the circumferential direction.

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