EP3486499B1 - Cooler ventilation module - Google Patents

Description

FIELD OF INVENTION

The present invention relates to a radiator fan module, in particular an electrically operated radiator fan module, in particular for motor vehicles, with struts located at the rear as seen in the main flow direction.

TECHNICAL BACKGROUND

The cooling system in an internal combustion engine, especially in a motor vehicle, mainly removes the heat that is released to the walls of the combustion chamber and cylinder because the combustion process is not ideal. Since temperatures that are too high would damage the engine (tearing off the lubricating film, burning the valves, etc.), the internal combustion engine must be actively cooled.

With a few exceptions, modern internal combustion engines, especially four-stroke engines in motor vehicles, are liquid-cooled, with a mixture of water, antifreeze and corrosion inhibitor usually serving as the coolant.

The coolant is pumped through hoses, pipes and/or channels through the engine (cylinder head and engine block) and, if necessary, through parts of the engine that are subject to high thermal stress, such as the exhaust turbocharger, generator or exhaust gas recirculation cooler. The coolant absorbs heat energy and carries it away from the above-mentioned components. The heated coolant flows on to a cooler. This cooler - previously often made of brass, today mostly made of Aluminum - is usually installed at the front of the vehicle, where an air flow absorbs heat energy from the coolant and cools it down before it flows back to the engine, thus closing the coolant circuit.

In order to drive the air through the radiator, a radiator fan module is provided in front of (upstream) or behind (downstream) the radiator in the (main) flow direction, which can be driven mechanically via a belt drive or electrically via an electric motor. The following statements refer to an electrically driven radiator fan module.

A cooling fan module traditionally consists of a fan frame, which has a fan wheel recess. A motor holder is arranged in the fan wheel recess, which is mechanically connected to the fan frame via struts. The struts can be arranged on the downstream or upstream side of the fan frame, based on the air volume flow. A motor, in particular an electric motor, is held in the motor holder. A fan wheel is arranged on an output shaft of the electric motor, which - driven by the electric motor - rotates in the fan wheel recess.

When designing and developing cooling fan modules, in addition to the air volume conveyed per unit of time, the available installation space, in particular its arrangement based on the air volume flow upstream or downstream of the cooler and/or its dimensions, and the noise development are always relevant.

With regard to noise development in particular, it is important whether the struts are arranged on the upstream or downstream side of the fan shroud, which is due to the fundamentally different aerodynamic properties of these two variants: While the air flows rather slowly and at least essentially laminarly on the upstream side (suction side) of the fan shroud, it is faster, denser and more turbulent than before on the downstream side (pressure side) of the fan shroud, i.e. after passing through the fan wheel recess. For this reason, the requirements for front and rear struts - apart from the main requirement of holding the motor mount - differ fundamentally from one another: While front struts can also take on supply and/or air conduction functions, these are at least essentially irrelevant for rear struts. Here it is more important to make the struts as "invisible" as possible from an aerodynamic point of view, i.e. to design the struts in such a way that they influence the downstream air flow as little as possible.

The EN 10 2012 112 211 A1 relates to a blower unit for a heat exchanger. The disclosed blower unit has straight, rear spokes which connect an annular support element for receiving an electric drive motor to a plate-like support structure.

The WO 2005/003569 A1 discloses a cooling fan module according to the preamble of claim 1.

The GB 2 344 619 A reveals a cooling fan module that has exactly two struts more than blade elements.

Against this background, the present invention is based on the object of providing an improved cooling fan module which is particularly advantageous with regard to noise development.

According to the invention, this object is achieved by a cooling fan module having the features of patent claim 1.

Accordingly, a cooling fan module according to the invention has a fan frame, a fan wheel recess which is formed in the fan frame, a motor holder which is mechanically connected to the fan frame via struts which are located at the rear as seen in the flow direction, a motor, in particular an electric motor, which is at least partially mounted in the motor holder, and a fan wheel which is arranged in the fan wheel recess and which is driven by the motor in rotation about a rotation axis, wherein the fan wheel has a plurality of blade elements, wherein at least all elements of a group which has at least one of the struts and at least one of the blade elements are forward-sickled or backward-sickled.

A "radiator fan module" in the sense of the present invention is in particular an assembly which, as seen in the flow direction, is arranged before or after a radiator of a vehicle and which is intended, in particular designed, to generate an air volume flow which extends through the radiator and/or around the radiator, wherein the air volume flow absorbs thermal energy from the radiator.

A "fan frame" in the sense of the present invention is in particular a frame in which the fan wheel is held and is itself preferably arranged, in particular fastened, on or near the cooler. A fan frame in the sense of the present invention preferably comprises a plastic material, in particular a plastic compound, in particular the fan frame is formed from this. Additionally and/or alternatively, the fan frame comprises a metal material, for example iron, steel, aluminum, magnesium or the like, in particular is at least partially, in particular at least substantially, in particular completely, formed from this. According to one embodiment, a fan frame can also have more than one fan wheel recess, a motor holder, a motor and a fan wheel; in particular, the present invention is suitable for use in radiator fan modules with two or more, in particular two, fan wheels. According to one embodiment, the fan frame additionally has at least one closable opening, in particular at least one flap, in particular a plurality of the same. This is particularly advantageous since further air guidance properties can be realized in this way.

A "fan wheel recess" in the sense of the present invention is in particular a material recess within the fan frame. According to one embodiment of the present invention, struts extend in the fan wheel recess, which mechanically, in particular electrically and/or electronically, connect a motor holder, which is also arranged in the fan wheel recess, to the fan frame. According to one embodiment of the present invention, the fan wheel recess is delimited by a frame ring.

A "motor holder" in the sense of the present invention is in particular a device for mechanically fastening the motor to the fan frame, in particular for providing the torque that counteracts the fan wheel. According to one embodiment, the motor holder is an at least substantially ring-shaped structure in which the motor is held. This is particularly advantageous because in this way a beneficial cooling air flow through the motor is not impaired.

"Flow direction" in the sense of the present invention refers in particular to the so-called main flow direction, i.e. the flow which passes parallel to the axis of rotation of the fan wheel through the fan wheel recess of the fan frame and is used to cool the cooler.

"Struts" in the sense of the present invention are in particular bar- or sickle-shaped structures which provide a mechanical connection between the motor mount and the fan frame. According to one embodiment of the present invention, the struts can have a teardrop-shaped cross-section in order to achieve advantageous aerodynamic and/or acoustic effects.

A "motor" in the sense of the present invention is in particular a machine that performs mechanical work by converting a form of energy, for example thermal/chemical or electrical energy, into kinetic energy, in particular a torque. This is particularly advantageous because in this way the fan frame can be operated at least essentially autonomously apart from the supply of energy, i.e. without being supplied with kinetic energy from outside, for example via a V-belt or toothed belt.

An "electric motor" in the sense of the present invention is an electromechanical converter (electric machine) that converts electrical power into mechanical power, in particular into torque. The term electric motor in the sense of the present invention includes, but is not limited to, direct current motors, alternating current motors and three-phase motors or brushed and brushless electric motors or internal rotor and external rotor motors. This is particularly advantageous because electrical energy is easy to transmit compared to mechanical or chemical energy. Form of energy with which the required torque is provided to drive the fan wheel.

A "fan wheel" in the sense of the present invention is in particular a rotationally symmetrical component which has a hub, in particular a hub pot, which connects the fan wheel to a motor, in particular via a shaft protruding from it, in such a way that the torque generated by the motor is at least substantially completely transmitted to the fan wheel.

A "vane element" in the sense of the present invention is an at least substantially flat body which is inclined relative to a plane on which the axis of rotation is perpendicular, which is arranged on the hub pot and which is intended, in particular designed, to generate an air volume flow as soon as the fan wheel is set in a rotary motion. The vane elements are preferably inclined relative to the axis of rotation in an angular range of -90° to +90°, in particular from -75° to +75°, in particular from -60° to +60°, in particular from -45° to +45°, in particular from -30° to +30° and particularly preferably from -15° to +15°. Vane elements in the sense of the present invention are also understood to mean in particular vanes, blades or rotor blades.

"Forward sickle" in the sense of the present invention means in particular that the tip of the wing element, viewed in the direction of rotation, leads the center of the wing element.

"Backward sickle" in the sense of the present invention means in particular that the tip of the wing element lags behind the center of the wing element when viewed in the direction of rotation.

According to the invention, the geometry of the at least one strut at least essentially follows the geometry of the at least one wing element with respect to the extension in a plane perpendicular to the axis of rotation. According to the invention, the geometry of the strut skeleton line of the at least one strut at least essentially follows the geometry of the wing element skeleton line of the at least one wing element with respect to the extension in a plane perpendicular to the axis of rotation. This is particularly advantageous because in this way at least one of the negative effects of the struts, in particular those at the rear, can be reduced, in particular with respect to acoustics. It is important to know that struts are always disruptive when developing fan frames. The volume flow generated by the fan wheel has an increased density, particularly in the direction of flow, just behind the fan wheel, and the individual air molecules move forward at very high speed and with a swirl generated by the fan wheel. In this initial situation, the air molecules hit the struts "standing in the way", which causes the air molecules to slow down and change direction. This creates undesirable noise, particularly when the blade, in particular its leading edge, passes over the strut. This creates unwanted noise, particularly the so-called "blocking", which is described in more detail below. By ensuring that the geometry of the strut follows the geometry of the wing element at least essentially in terms of radial extension, it is possible to ensure that the leading edge of the wing element does not hit the strut at the same time over its entire length, but that there is always only one overlap point that moves in the radial direction. For example, consider a commercially available Paper scissors in which the intersection point of the two cutting edges moves along the direction of extension as soon as the scissors are closed.

According to one embodiment of the present invention, the group comprises a plurality, in particular all, of the struts and/or a plurality, in particular all, of the wing elements.

This is particularly advantageous because the effect described above is enhanced in this way. The more struts or wing elements are coordinated with one another according to the invention, the more advantageous the properties of the cooling fan module are in terms of noise development.

$$\begin{array}{c}Y-\mathit{Koordinate}=f\left({\alpha }_S\left(n\right),{\alpha }_R,D_H,L_P,n,{\beta }_S\left(n\right),{\beta }_R\left(n\right)\right)\\ =\cos \left({\alpha }_{S\left(n\right)}\cdot \left(\frac{D_H}{2}+\frac{L_P\cdot n}{n_{\mathit{max}}}\right)\right)+{\beta }_S\left(n\right)+\cos \left({\alpha }_S\left(n\right)+\frac{{\alpha }_R}{2}\right)\cdot \frac{L_P\cdot n}{n_{\mathit{max}}}\cdot \sqrt{2}\cdot \sqrt{1-\cos \left({\alpha }_R\right)}+{\beta }_R\left(n\right)\end{array}$$

wobei gilt:

X-Koordinate

beschreibt die X-Koordinate des Schnittpunktes der Strebenskelettlinie mit einer Schnittebene in einem x-y-Koordinatensystem in der Schnittebene

Y-Koordinate

beschreibt die Y-Koordinate des Schnittpunktes der Strebenskelettlinie mit einer Schnittebene in einem x-y-Koordinatensystem in der Schnittebene

n

beschreibt einen aktuell betrachteten Profilschnitt

nmax

beschreibt, in wie viele äquidistante Profilschnitte die Strebe und das Flügelelement über ihre radiale Erstreckung hinweg unterteilt werden; wobei

$$n_{\max }\in \left[5,25\right]$$

αs(n)

beschreibt einen Sichelungswinkel am Profilschnitt n des Flügelelements, d.h. einen Winkel zwischen einem zur Rotationsachse parallel verschobenen ersten Schenkel und einem zweiten Schenkel, welcher durch die Punkte von Vorderund Hinterkante der Strebe in der Schnittebene definiert ist;

DH

beschreibt den Außendurchmesser des Motorhalters (3) ;

LP

beschreibt die Profillänge der Strebe (10), d.h. den Abstand zwischen Vorder- und Hinterkante der Strebe in der Schnittebene;

βs(n)

beschreibt einen Korrekturfaktor der Sichelung, wobei $${\beta }_s\left(n\right)\in \left[-5;5\right]$$

β_R(n) beschreibt einen Korrekturfaktor der Profilrotation, wobei $${\beta }_R\left(n\right)\in \left[-30;30\right]$$

According to a further embodiment of the present invention, a wing element skeleton line of the wing elements of the group and a strut skeleton line of the struts of the group are related to each other in a profile section via: $$\begin{array}{c}X-\mathit{coordinate}=e\left({\alpha }_S\left(n\right),{\alpha }_R,D_H,L_P,n,{\beta }_S\left(n\right),{\beta }_R\left(n\right)\right)\\ =\sin \left({\alpha }_{S\left(n\right)}\cdot \left(\frac{{\mathrm{<figure-callout\; id="2"\; label="D\; H"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">D</figure-callout>}}_H}{2}+\frac{L_P\cdot n}{n_{\mathit{Max}}}\right)\right)+{\beta }_S\left(n\right)+\cos \left({\alpha }_S\left(n\right)+\frac{{\alpha }_{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">R</figure-callout>}}}{2}\right)\cdot \frac{L_P\cdot n}{n_{\mathit{Max}}}\cdot \sqrt{2}\cdot \sqrt{1-\cos \left({\alpha }_R\right)}+{\beta }_R\left(n\right)\end{array}$$

$$\begin{array}{c}Y-\mathit{coordinate}=e\left({\alpha }_S\left(n\right),{\alpha }_R,D_H,L_P,n,{\beta }_S\left(n\right),{\beta }_R\left(n\right)\right)\\ =\cos \left({\alpha }_{S\left(n\right)}\cdot \left(\frac{{\mathrm{<figure-callout\; id="2"\; label="D\; H"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">D</figure-callout>}}_H}{2}+\frac{L_P\cdot n}{n_{\mathit{Max}}}\right)\right)+{\beta }_S\left(n\right)+\cos \left({\alpha }_S\left(n\right)+\frac{{\alpha }_{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">R</figure-callout>}}}{2}\right)\cdot \frac{L_P\cdot n}{n_{\mathit{Max}}}\cdot \sqrt{2}\cdot \sqrt{1-\cos \left({\alpha }_R\right)}+{\beta }_R\left(n\right)\end{array}$$

where:

X-coordinate

describes the X-coordinate of the intersection point of the strut skeleton line with a cutting plane in an xy-coordinate system in the cutting plane

Y-coordinate

describes the Y-coordinate of the intersection point of the strut skeleton line with a cutting plane in an xy-coordinate system in the cutting plane

n

describes a currently viewed profile section

nmax

describes how many equidistant profile sections the strut and the wing element are divided into over their radial extension; where

$$n_{\mathrm{Max}}\in \left[5,25\right]$$

αs(n)

describes a sickle angle at the profile section n of the wing element, ie an angle between a first leg displaced parallel to the axis of rotation and a second leg, which is defined by the points of the leading and trailing edges of the strut in the cutting plane;

DH

describes the outer diameter of the motor mount (3);

LP

describes the profile length of the strut (10), ie the distance between the front and rear edges of the strut in the cutting plane;

βs(n)

describes a correction factor of the sickle, where $${\beta }_s\left(n\right)\in \left[-5;5\right]$$

β _R (n) describes a correction factor of the profile rotation, where $${\beta }_R\left(n\right)\in \left[-30;30\right]$$

A "strut skeleton line" in the sense of the present invention, also called profile center line, camber line or curvature line, refers to the connecting line of the circle centers inscribed in a profile, whereby the skeleton line runs straight from the nose circle center to the profile nose. Another alternative definition, which in the sense the invention is explicitly included, defines the strut skeleton line in such a way that it consists of the midpoints between the top and bottom perpendicular to the X coordinate or profile chord. The course of the skeleton line determines the flow properties to a large extent. Important geometric parameters are the camber height and the camber offset, whereby strut profiles with a straight or S-shaped skeleton line have a pressure point that changes only slightly with the angle of attack.

A "wing element skeleton line" in the sense of the above invention, also called profile center line, camber line or curvature line, refers to the connecting line of the circle centers inscribed in a profile, with the skeleton line running straight from the nose circle center to the profile nose. Another alternative definition, which is explicitly included in the sense of the invention, defines the wing element skeleton line as consisting of the centers between the upper and lower sides perpendicular to the X coordinate or profile chord. The course of the skeleton line significantly determines the flow properties. Important geometric parameters are the camber height and the camber offset, with wing element profiles with a straight or S-shaped skeleton line having a pressure point that changes only slightly with the angle of attack.

The above functional relationships are the result of extensive scientific investigations and tests, which describe for the first time a relationship between the strut skeleton line and the wing element skeleton line. For this purpose, the radial extension direction of the wing elements or struts is divided into a number n _max equidistant profile sections, whereby the relationships described here apply to at least one, in particular a majority, in particular a predominant majority, n _max profile sections must be fulfilled.

The geometry of the wing element is directly incorporated into the design of the strut via the wing element skeleton line, which creates the sickle of the wing element.

The formula contains parameters of the wing element skeleton line in the form of the sickle angle α _s (n) at the profile section n of the wing element. This means that for the first time there is a functional connection between the geometry of the wing element and the strut, which leads to a particularly advantageous sound image of the overall system. This is particularly relevant for electrically powered vehicles, which emit significantly less noise, which is why a previously known radiator fan module would lead to an unpleasant noise perception, since the masking noise of the classic main drive system, i.e. the combustion engine, is eliminated.

According to a further embodiment of the present invention, the defined functional relationships for X and Y coordinates apply to all sections n ∈ [0; n _max ].

This is particularly advantageous because the defined functional relationships for X and Y coordinates, which have proven to be advantageous in extensive series of tests, apply to the entire radial extension of the wing element and strut. This means that the advantageous effect of noise reduction can be further improved because the wing element can sweep over the struts "gently", i.e. with a reduced influence on the flow vector of the main volume flow.

According to a further embodiment of the present invention, the struts have a semi-symmetrical profile.

A "profile" in the sense of the present invention is in particular the shape of the cross section of the strut, with the cutting plane being perpendicular to a radial vector of the cooling fan module. This radial vector is defined on the one hand by the orientation of the axis of rotation to which this vector is perpendicular, and the point of the strut skeleton line in the cutting plane to be considered.

A "semi-symmetrical profile" in the sense of the present invention, also called a biconvex profile, is to be understood as a profile with a low curvature, in particular in the range of 1-3%, which has a curvature but no concave contours.

This is particularly advantageous because in this way the above-described advantages of the cooling fan module according to the invention can be further improved by not only optimizing the position of the strut in relation to the wing element, but also the design of the strut so that it fits into the main volume flow as advantageously as possible in order to avoid diversion and/or redirection of the air volume flow as much as possible.

According to a further embodiment of the present invention, the struts are arranged with an angle of attack α in the range between 5 degrees and 45 degrees, preferably between 10 degrees and 25 degrees, relative to the axis of rotation.

The "angle of attack" in the sense of the present invention, also called "angle of attack", is the angle between the direction of the incoming fluid and the core of the profile, i.e. the imaginary straight line connection between the profile nose and the profile trailing edge.

This is particularly advantageous because it provides a further parameter with which the strut can be designed in such a way that the diversion and/or deflection of the main volume flow is further reduced.

According to a further embodiment of the present invention, the struts emerge from the engine mount at an angle β which has a value in the range of -30° to +30°, in particular in the range of -20° to +20°, in particular in the range of -10° to +10°.

This is particularly advantageous because extensive test and comparison studies have shown that if the strut emerges from the engine mount too steeply, the length is increased considerably, thereby canceling out or possibly reversing a positive effect caused by a "gentle" sliding of the edges over each other through the length of the strut.

According to a further embodiment of the present invention, the struts enter the fan frame at a predetermined angle ϕ, which has a value in the range of -90° and +30°, in particular in the range of -75° and +15°, in particular in the range of -60° to 0°. This is particularly advantageous because in this way the struts can also be arranged as protection against interference and can be adapted to the available installation space when designing the system.

According to a further embodiment of the present invention, a reinforcement is provided which is formed between the engine mount and one of the struts, in particular between the engine mount and a plurality of the struts, in particular between the engine mount and each strut.

This is particularly advantageous because it improves the rigidity of the cooling fan module as a whole and especially of the struts. This stiffening between the engine mount and the strut is particularly advantageous because the counter torque to the drive torque of the engine causes high shear forces to occur at the transition between the engine mount and the strut. Furthermore, the above-mentioned advantages of a material accumulation in the strut area directly on the engine mount at least partially compensate for the associated aerodynamic disadvantages because the rotation and volume flow speed in this area is comparatively low compared to the outer radius of the blade elements.

The reinforcement is designed in particular in the form of a material accumulation which increases the radius at the transition from the strut to the engine mount in order to enable, in particular, improved force introduction.

This is particularly advantageous according to one embodiment, since the reinforcement increases the strength of a strut, so that the strut is very dimensionally stable. The reinforcement is preferably formed in one piece with the strut and/or the motor mount.

According to a further embodiment of the present invention, the fan shroud, the motor mount and the struts are formed as a one-piece plastic injection-molded part.

This is particularly advantageous because it allows a cost-effective near-to-end-shape primary forming process to be used to provide the fan shroud together with the motor mount and struts.

According to a further embodiment of the present invention, the struts have a reinforcement.

According to a further embodiment, the reinforcement comprises at least some metal. For example, the reinforcement is in the form of a steel sheet. This is particularly advantageous according to one embodiment, since the dimensional stability and strength of the struts can be increased in this way.

The cooling fan module has exactly two struts more than blade elements, in particular the cooling fan module has eleven struts and nine blade elements. This design is particularly advantageous because in this way each blade element is in a different phase of sweeping over the strut, which leads to a more homogeneous noise emission with regard to the overall system.

The above embodiments and developments can be combined with one another as desired, unless the description clearly indicates otherwise to the person skilled in the art. Other possible embodiments, developments and implementations of the invention also include combinations of features of the invention described above or below with regard to the exemplary embodiments that were not explicitly mentioned. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention.

TABLE OF CONTENTS OF THE DRAWING

Fig. 1

eine schematische Draufsicht auf eine Lüfterzarge aus dem Stand der Technik mit einer angedeuteten Strebe gemäß einer Ausführungsform der vorliegenden Erfindung;

Fig. 2

eine schematische Draufsicht auf einen Ausschnitt einer Lüfterzarge nach einer Ausführungsform der vorliegenden Erfindung;

Fig. 3

eine schematische Draufsicht auf einer Lüfterzarge nach einer weiteren Ausführungsform der vorliegenden Erfindung, nebst zweier Schnittdarstellungen;

Fig. 4

eine schematische perspektivische Darstellung einer einzelnen Strebe gemäß einer Ausführungsform der vorliegenden Erfindung;

Fig. 5

eine schematische perspektivische Darstellung des Profils und des Verlaufs der Strebenskelettlinie einer einzelnen Strebe gemäß einer Ausführungsform der vorliegenden Erfindung;

Fig. 6

eine schematische dreidimensionale Detailansicht einer einzelnen Strebe zwischen Motorhalter und Lüfterzarge gemäß einer Ausführungsform der vorliegenden Erfindung;

Fig. 7

eine schematische Schnittansicht einer einzelnen Strebe gemäß einer Ausführungsform der vorliegenden Erfindung;

Fig. 8

eine schematische Schnittansicht einer einzelnen Strebe mit Armierung gemäß einer weiteren Ausführungsform der vorliegenden Erfindung;

Fig. 9a

ein Diagramm mit Messwerten eines Kühlerlüftermoduls des Standes der Technik; und

Fig. 9b

ein Diagramm mit Messwerten eines Kühlerlüftermoduls gemäß einer Ausführung der vorliegenden Erfindung.

The present invention is explained in more detail below with reference to the embodiments shown in the schematic figures of the drawing. They show:

Fig.1

a schematic plan view of a fan frame from the prior art with an indicated strut according to an embodiment of the present invention;

Fig.2

a schematic plan view of a section of a fan frame according to an embodiment of the present invention;

Fig.3

a schematic plan view of a fan frame according to a further embodiment of the present invention, together with two sectional views;

Fig.4

a schematic perspective view of a single strut according to an embodiment of the present invention;

Fig.5

a schematic perspective representation of the profile and the course of the strut skeleton line of a single strut according to an embodiment of the present invention;

Fig.6

a schematic three-dimensional detailed view of a single strut between the engine mount and the fan shroud according to an embodiment of the present invention;

Fig.7

a schematic sectional view of a single strut according to an embodiment of the present invention;

Fig.8

a schematic sectional view of a single strut with reinforcement according to another embodiment of the present invention;

Fig. 9a

a diagram with measured values of a prior art cooling fan module; and

Fig. 9b

a diagram with measured values of a cooling fan module according to an embodiment of the present invention.

The accompanying drawing figures are intended to provide a further understanding of embodiments of the invention. They illustrate embodiments and, in conjunction with the description, serve to explain principles and concepts of the invention. Other embodiments and many of the aforementioned advantages will be apparent upon reference to the drawings. The elements of the drawings are not necessarily shown to scale with respect to one another.

In the figures of the drawing, identical, functionally identical and acting elements, features and components are provided with the same reference symbols, unless otherwise stated.

Fig.1 shows a schematic plan view of a fan frame 2 of a radiator fan module 1 from the prior art with an indicated strut 10 according to an embodiment of the present invention. The cooling fan module 1 has a fan frame 2, a fan wheel recess 4 which is formed in the fan frame 2, a motor holder 3 which is mechanically connected to the fan frame 2 via (previously known, straight) struts 100 which are located at the rear as seen in the flow direction, a motor, in particular an electric motor, 5 which is at least partially mounted in the motor holder 3, a fan wheel 6 which is arranged in the fan wheel recess 4 and which is driven by the motor 5 in rotation about a rotation axis R, wherein the fan wheel 6 has a plurality of blade elements 6a.

The motor mount 3 is connected to the fan frame 2 via straight struts 100, as are well known from the prior art. The reference number 10 in the Fig.1 already indicated a strut according to the invention, as will be described in detail below. In Fig.1 In particular, the geometric difference between previously known struts 100 and the struts 10 according to the invention can be seen.

Fig.2 shows a schematic plan view of a section of a fan frame 2 according to an embodiment of the present invention.

The fan frame 2 is made of plastic, in particular in the form of a one-piece plastic injection-molded part.

The struts 10 extend parabolically from the edge of the fan wheel recess 4 to the motor holder 3 and hold the motor holder in position in the fan wheel recess 4. The struts 10 each have a reinforcement 11 which secures the connection between the motor holder 3 and one of the Struts 10 are reinforced. The reinforcement 11 is preferably formed in one piece with the strut 10. Preferably, the fan frame 2, the struts 10 and the motor mount 3 are a one-piece plastic injection molded part. Fastening interfaces 30 are provided on the motor mount 3, to which a motor 5 can be attached. Furthermore, the angle β is shown, which indicates the angle at which the strut 10 enters the motor mount 3. The sides of the angle β are, on the one hand, an extension vector 14 of the strut 10 at the exit point of the strut 10 from the motor mount 3 and, on the other hand, a radial vector 15 through the exit point of the strut 10 from the motor mount 3. According to one embodiment of the present invention, β has a value in the range from -30° to +30°.

Furthermore, an angle ϕ is shown, which indicates at which angle the strut 10 enters the edge of the fan wheel recess 4. The sides of the angle ϕ are, on the one hand, an extension vector 16 of the strut 10 at the entry point of the strut 10 into the fan frame 2 and, on the other hand, a radial vector 16a through the entry point of the strut 10 into the fan frame 2. According to one embodiment of the present invention, ϕ has a value in the range of -90° and +30°.

In the further course, in connection with the design of the strut 10 according to the invention, a starting point 17 and an end point 18 are occasionally mentioned. The starting point 17 is the exit point of the strut 10 from the motor mount 3 and the end point 18 is defined by the entry point of the strut 10 into the fan frame 2.

Fig.3 shows a schematic plan view of a fan frame 2 according to a further embodiment of the present Invention together with two sectional views. The Fig.3 The cooling fan module 1 shown is a cooling fan module with rear struts 10, ie viewed in the flow direction, which according to the illustration of the Fig.3 out of the blade, the air is first accelerated and compressed by the rotating fan wheel 6 before it hits the struts 10, which represents a particular challenge in the design of such cooling fan modules and in particular the struts 10.

In this figure, the fan wheel 6 with the plurality of blade elements 6a is shown for the first time. In this illustration, the effect according to the invention can be seen particularly well, how the blade elements 6a - from the perspective of the illustration of the Fig.3 - behind the struts 10 and past them. According to the preferred embodiment of the Fig.3 the fan frame 2 has eleven struts 10 according to the invention and the fan wheel 6 has nine blade elements 6a. This structural property ensures that each blade element 6a is in a different phase of sweeping over one of the struts 10 at any time during the rotation of the fan wheel. This leads to advantageous, in particular more homogeneous, noise radiation of the entire system.

Fig.4 shows a schematic perspective view of a single strut 10 according to an embodiment of the present invention. This connects the motor holder 3 to the fan frame 2 and holds the motor holder 3 in position in the fan wheel recess 4 of the fan frame 2. The struts 10 provide the counter torque which is opposite to the torque generated by the motor with which the fan wheel 6 is driven. For this reason, the struts 10 high forces are conducted, which leads to increased rigidity requirements for it. The strut 10 has a parabolic shape. A skeleton line 12 of the strut 10 runs from the starting point 17 on the motor mount to the end point 18 on the fan frame 2. The apex 13 of the strut is located in the axial direction at least substantially in the middle of the strut 10.

The strut 10 also has an airfoil profile. An area around a leading edge 26 of a profile 20, in particular a cross-sectional profile, is thicker than an area around a trailing edge 27 of the profile 20. According to a particularly preferred embodiment, the airfoil profile of the strut 10 is a semi-symmetrical profile.

Fig.5 shows a schematic perspective representation of the profile and the course of the strut skeleton line of a single strut 10 according to an embodiment of the present invention. The profile 20 of the strut 10 is designed as a semi-symmetrical profile according to this embodiment, wherein the skeleton line 12 of the strut 10 runs parabolically.

$$\begin{array}{c}Y-\mathit{Koordinate}=f\left({\alpha }_S\left(n\right),{\alpha }_R,D_H,L_P,n,{\beta }_S\left(n\right),{\beta }_R\left(n\right)\right)\\ =\cos \left({\alpha }_{S\left(n\right)}\cdot \left(\frac{D_H}{2}+\frac{L_P\cdot n}{n_{\mathit{max}}}\right)\right)+{\beta }_S\left(n\right)+\cos \left({\alpha }_S\left(n\right)+\frac{{\alpha }_R}{2}\right)\cdot \frac{L_P\cdot n}{n_{\mathit{max}}}\cdot \sqrt{2}\cdot \sqrt{1-\cos \left({\alpha }_R\right)}+{\beta }_R\left(n\right)\end{array}$$

wobei gilt:

X-Koordinate

beschreibt die X-Koordinate des Schnittpunktes der Strebenskelettlinie mit einer Schnittebene in einem x-y-Koordinatensystem in der Schnittebene

Y-Koordinate

beschreibt die Y-Koordinate des Schnittpunktes der Strebenskelettlinie mit einer Schnittebene in einem x-y-Koordinatensystem in der Schnittebene

n

beschreibt einen aktuell betrachteten Profilschnitt

nmax

beschreibt, in wie viele äquidistante Profilschnitte die Strebe und das Flügelelement über ihre radiale Erstreckung hinweg unterteilt werden; wobei

$$n_{\max }\in \left[5,25\right]$$

αs(n)

beschreibt einen Sichelungswinkel am Profilschnitt n des Flügelelements, d.h. einen Winkel zwischen einem zur Rotationsachse parallel verschobenen ersten Schenkel und einem zweiten Schenkel, welcher durch die Punkte von Vorder- und Hinterkante der Strebe in der Schnittebene definiert ist;

DH

beschreibt den Außendurchmesser des Motorhalters (3);

Lp

beschreibt die Profillänge der Strebe (10), d.h. den Abstand zwischen Vorderund Hinterkante der Strebe in der Schnittebene;

βs(n)

beschreibt einen Korrekturfaktor der Sichelung, wobei $${\beta }_s\left(n\right)\in \left[-5;5\right];$$

und

βR(n)

beschreibt einen Korrekturfaktor der Profilrotation, wobei $${\beta }_R\left(n\right)\in \left[-30;30\right],$$

wobei die definierten funktionalen Zusammenhänge für X- und Y-Koordinaten für alle Schnitte n ∈ [0;n _max] bei n_max=10 gelten.In particular, a wing element skeleton line of the wing element 6a and the strut skeleton line 12 in a profile section are related to each other via the following mathematical relationships: $$\begin{array}{c}X-\mathit{coordinate}=e\left({\alpha }_S\left(n\right),{\alpha }_R,D_H,L_P,n,{\beta }_S\left(n\right),{\beta }_R\left(n\right)\right)\\ =\sin \left({\alpha }_{S\left(n\right)}\cdot \left(\frac{{\mathrm{<figure-callout\; id="2"\; label="D\; H"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">D</figure-callout>}}_H}{2}+\frac{L_P\cdot n}{n_{\mathit{Max}}}\right)\right)+{\beta }_S\left(n\right)+\cos \left({\alpha }_S\left(n\right)+\frac{{\alpha }_{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">R</figure-callout>}}}{2}\right)\cdot \frac{L_P\cdot n}{n_{\mathit{Max}}}\cdot \sqrt{2}\cdot \sqrt{1-\cos \left({\alpha }_R\right)}+{\beta }_R\left(n\right)\end{array}$$

$$\begin{array}{c}Y-\mathit{coordinate}=e\left({\alpha }_S\left(n\right),{\alpha }_R,D_H,L_P,n,{\beta }_S\left(n\right),{\beta }_R\left(n\right)\right)\\ =\cos \left({\alpha }_{S\left(n\right)}\cdot \left(\frac{{\mathrm{<figure-callout\; id="2"\; label="D\; H"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">D</figure-callout>}}_H}{2}+\frac{L_P\cdot n}{n_{\mathit{Max}}}\right)\right)+{\beta }_S\left(n\right)+\cos \left({\alpha }_S\left(n\right)+\frac{{\alpha }_{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">R</figure-callout>}}}{2}\right)\cdot \frac{L_P\cdot n}{n_{\mathit{Max}}}\cdot \sqrt{2}\cdot \sqrt{1-\cos \left({\alpha }_R\right)}+{\beta }_R\left(n\right)\end{array}$$

where:

X-coordinate

describes the X-coordinate of the intersection point of the strut skeleton line with a cutting plane in an xy-coordinate system in the cutting plane

Y-coordinate

describes the Y-coordinate of the intersection point of the strut skeleton line with a cutting plane in an xy-coordinate system in the cutting plane

n

describes a currently viewed profile section

nmax

describes how many equidistant profile sections the strut and the wing element are divided into over their radial extension; where

$$n_{\mathrm{Max}}\in \left[5,25\right]$$

αs(n)

describes a sickle angle at the profile section n of the wing element, ie an angle between a first leg displaced parallel to the axis of rotation and a second leg, which is defined by the points of the leading and trailing edges of the strut in the cutting plane;

DH

describes the outer diameter of the motor mount (3);

LP

describes the profile length of the strut (10), ie the distance between the front and rear edges of the strut in the cutting plane;

βs(n)

describes a correction factor of the sickle, where $${\beta }_s\left(n\right)\in \left[-5;5\right];$$

and

βR(n)

describes a correction factor of the profile rotation, where $${\beta }_R\left(n\right)\in \left[-30;30\right],$$

where the defined functional relationships for X and Y coordinates apply to all sections n ∈ [0; n _max ] at n _max =10.

Fig.6 shows a schematic three-dimensional detailed view of a single strut 10 between the motor mount 3 and the fan frame 2 according to an embodiment of the present invention. In this illustration, the reinforcement 11 between the strut 10 and the motor mount 3 can be seen. The reinforcement 11 has a wall 19 which extends from the strut 10 at an angle. According to one embodiment, this angle corresponds in amount to the angle β, so that the strut 10 and the wall 19 are arranged mirror-symmetrically to a vertical of the circular motor mount 3. The strut 10 is made more stable by the wall 19 and can therefore hold the motor 5 securely in position in the motor mount 3. The reinforcement 11 is formed integrally with the strut 10 and the motor mount 3 according to the embodiment shown.

Fig.7 shows a schematic sectional view of a single strut 10 according to an embodiment of the present invention. The profile 20 of the strut 10 according to this embodiment is a semi-symmetrical profile 20. A profile curvature of the upper side 21 and a profile curvature of the lower side 22 of the profile 20 run in the same direction. The upper side 21 is concavely curved while the lower side 22 has a convex curvature. Furthermore, the profile 20 has a profile thickness 23 and a profile depth 25. Furthermore, the profile 20 has a nose radius 24, which indicates the radius of the nose of the profile. The area of the trailing edge 27 of the profile 20 is narrower than the area of the leading edge 26 of the profile 20. The angle of attack α of the profile according to this embodiment is approximately 45 degrees normal to the blade surface. The air flows in the direction of the arrow 29 around the strut 10.

Fig.8 shows a schematic sectional view of a single strut 10 according to a further embodiment of the present invention. In this embodiment of the strut 10, a reinforcement 31 is provided in the strut 10. The reinforcement 31 can at least partially comprise metal. For example, the reinforcement 31 is made of a steel sheet. Alternatively, the reinforcement 31 can also be made of aluminum. This design allows the strut 10 to be made particularly dimensionally stable.

Fig. 9a shows a diagram with measured values of a state-of-the-art cooling fan module and Fig. 9b a diagram with measured values of a cooling fan module according to an embodiment of the present invention.

In the Fig. 9a and 9b The diagrams shown each show the course of a total level and a fan blade order generated by the system. The total level indicates the total noise radiation across all frequencies. In both figures, this is the eleventh fan blade order, which depends on the number of blades, their geometric arrangement and sickle.

Furthermore, the so-called 10 dB criterion is specified, which runs at a distance of 10 dB below the total level. The 10 dB criterion is particularly relevant for evaluating the sound of a fan noise: The 10 dB criterion states that those frequency components that are below this 10 dB criterion are not perceived as disturbing. You can imagine it as in an open-plan office, where individual voices are drowned out by the general murmur. Conversely, noise components that violate this 10 dB criterion are perceived as particularly disturbing. If all frequency components are below the 10 dB criterion, the noise radiation is perceived as a pleasant, "rich" hum.

The pictured Fig. 9a and 9b have been measured at component level in a semi-anechoic chamber with a heat exchanger. The design of the struts according to an embodiment of the present invention significantly improves the eleventh fan blade order compared to the state of the art. The total level improves by up to 4 dB compared to the state of the art and thus now meets the 10 dB criterion for the first time.

The struts can, for example, be provided on the pressure side and/or on the vacuum side.

List of reference symbols

1

Radiator fan module

2

Fan frame

3

Engine mount

4

Fan wheel recess

5

Fan wheel

5a

Wing elements

10

strut

11

Reinforcement

12

Skeleton line

13

Vertex of the skeletal line

14

Extension vector of the strut at the exit point of the strut from the engine mount

15

Radial vector through the exit point of the strut from the engine mount

16

Extension vector of the strut at the entry point of the strut into the fan frame

16a

Radial vector through the entry point of the strut into the fan shroud

17

Starting point

18

Endpoint

19

Reinforcing wall

20

profile

21

Profile curvature of the top

22

Profile curvature of the underside

23

Profile thickness

24

Nose radius

25

Tread depth

26

Front edge

27

Trailing edge

28

Perpendicular to the engine mount

29

Direction of air flow

30

Mounting interface

31

reinforcement

100

previously known, straight struts

1

Profile length

r2

Radius top curvature

r3

Radius bottom curvature

H

Height

d1

Profile nose diameter

d2

Trailing edge diameter

R

Rotation axis

α

Angle of attack

β

angle

ϕ

angle

Claims (10)

1. Cooling fan module (1) comprising:

   a fan shroud (2);

   a fan propeller cutout (4), which is formed in the fan shroud (2);

   a motor mount (3) which is mechanically connected to the fan shroud (2) by means of struts (10) which are located at the rear viewed in the flow direction;

   a motor, in particular electric motor (5), which is mounted at least partially in the motor mount (3);

   a fan propeller (6) which is arranged in the fan propeller cutout (4) and which is driven rotationally about a rotational axis (R) by the motor (5), wherein the fan propeller has a plurality of blade elements (6a),

   wherein at least all the elements of a group which has at least one of the struts (10) and at least one of the blade elements (6a) are forward-sickled or rearward-sickled,

   wherein a blade element mean line of at least one of the blade elements (6a) of the group and a strut mean line of the struts (10) of the group in a profile section are related to one another such that the geometry of the at least one strut (10) of the group follows at least essentially the geometry of the at least one blade element (6a) of the group with respect to the extent in a plane perpendicular to the rotational axis (R),

   characterized in that

   the cooling fan module (1) has exactly two struts (10) more than blade elements (6a).
2. Cooling fan module according to Claim 1, wherein the group comprises a plurality, in particular all, of the struts and/or a plurality, in particular all, of the blade elements (6a).
3. Cooling fan module according to Claim 1 or 2, wherein the cooling fan module (1) has eleven struts and nine blade elements.
4. Cooling fan module according to one of the preceding claims, wherein the struts (10) have a semi-symmetrical aerofoil profile.
5. Cooling fan module according to one of the preceding claims, wherein the struts (10) are arranged with respect to the rotational axis (R) at a blade angle α in the range between 5 degrees and 45 degrees, preferably between 10 degrees and 25 degrees.
6. Cooling fan module according to one of the preceding claims, wherein the struts (10) emerge from the motor mount (3) at an angle β which has a value in the range from -30° to +30°.
7. Cooling fan module according to one of the preceding claims, wherein the struts (10) enter the fan shroud (2) at a predefined angle ϕ which has a value in the range from -90° to +30°.
8. Cooling fan module according to one of the preceding claims, wherein a strengthening element (11) is provided which is formed between the motor mount (3) and one of the struts (10).
9. Cooling fan module according to one of the preceding claims, wherein the fan shroud (2), the motor mount (3) and the struts (10) are formed as a single-piece plastics injection mould part.
10. Cooling fan module according to one of the preceding claims, wherein the struts (10) have a reinforcement element (31).

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