EP3450716B1 - Fan wheel and cooling fan module comprising such a fan wheel - Google Patents

Description

The present invention relates to a fan wheel with backward sickle blades for a cooling fan module, in particular an electrically operated cooling fan module, in particular for motor vehicles.

The cooling system of an internal combustion engine, in particular of a motor vehicle, mainly dissipates that heat which is given off to the walls of the combustion chambers and cylinders because the combustion process is not ideal. Since excessively high temperatures would damage the engine (tearing off the lubricating film, burning the valves, etc.), the combustion engine must be actively cooled.

Modern internal combustion engines, especially four-stroke engines in motor vehicles, are, with a few exceptions, liquid-cooled, a mixture of water, antifreeze and anti-corrosion agent being used as the coolant.

The coolant is pumped through hoses, pipes and / or ducts through the engine (cylinder head and engine block) and, if necessary, through thermally highly stressed engine components, such as exhaust gas turbochargers, generators or exhaust gas recirculation coolers. The coolant absorbs thermal energy and removes it from the above-mentioned components. The heated coolant flows on to a cooler. This cooler - in the past often made of brass, now mostly made of aluminum - is usually attached to the front of the vehicle, where a stream of air absorbs heat energy from the coolant and cools it down before it flows back to the engine, which closes the coolant circuit.

In order to force the air through the cooler, a flow direction is taken before the cooler (ie upstream) or after the cooler (ie downstream) Cooling fan module is provided, which can be driven mechanically via a belt drive or electrically via an electric motor. The following statements refer to an electrically driven cooling fan module.

A cooling fan module classically consists of a fan frame, which has a fan wheel recess, and a fan wheel, which is rotatably held in the fan wheel recess.

The geometry of the fan wheel has a decisive influence on both the amount of air conveyed and the acoustic properties of the cooling fan module.

Classic fan wheels (s. Figures 1A and 1B ) have an at least substantially flat or slightly curved edge geometry on the blades.

The present invention is based on the object of specifying an advantageous fan wheel which is particularly advantageous with regard to its air delivery properties and / or its acoustic properties.

This object is achieved according to the invention by a fan wheel according to claim 1 and a cooling fan module according to claim 7. Preferred developments of the fan wheel and the cooling fan module are the subject of the subclaims and the following description.

According to the invention, the object is achieved by a fan wheel according to claim 1.

According to one embodiment of the present invention, this is particularly advantageous since a favorable air volume flow can be achieved in this way. Comparative measurements, which are explained in detail in the description of the figures, have shown that a fan wheel according to the present invention can achieve, in particular, a higher air volume flow compared to an otherwise structurally identical fan wheel with a flat or curved rear edge. In other words: the same air volume flow can be generated with a power saving or a slower running fan wheel according to the present invention. Alternatively, a higher air volume flow can be achieved with the same output.

A "fan wheel" in the sense of the present invention is in particular a rotationally symmetrical component that connects a hub, in particular a hub pot, which connects the fan wheel to a motor, in particular via a shaft protruding from this, in such a way that the torque generated by the Motor is generated, is at least substantially completely transferred to the fan wheel. Furthermore, the fan wheel has a plurality of blades, which are provided, in particular are set up to generate an air volume flow as soon as the fan wheel is set in a rotary motion. The blades are preferably inclined with respect to the axis of rotation in an angular range of -90 ° to + 90 °.

A "hub pot" in the sense of the present invention is in particular a central part of the fan wheel, which is arranged at least essentially in the middle of the fan wheel, provides a connection to a drive, in particular a motor, in particular an electric motor, this drive, in particular a motor , in particular an electric motor, at least partially and which, like a classic pot, is composed of an at least substantially flat base surface and an adjoining cylinder surface. In particular, the blades are arranged, in particular molded, on this cylindrical outer wall.

A "blade" in the sense of the present invention is a flat body which is inclined with respect to a plane on which the axis of rotation is perpendicular, which is arranged on the hub cup and which is intended, in particular set up, to generate an air volume flow as soon as the fan wheel is in a rotational movement is displaced. Blade blades in the context of the present invention are also understood in particular to mean blades or rotor blades.

A "leading edge" of the airfoil in the sense of the present invention is in particular that edge which leads in the direction of rotation.

A “trailing edge” of an airfoil in the sense of the present invention is in particular that edge of the airfoil which, viewed in the direction of rotation, lags behind.

An “orthogonal projection” within the meaning of the present invention is an image of a point on a plane, so that the connecting line between the point and its image forms a right angle with this plane. The image then has the shortest distance to the starting point of all points on the plane. The orthogonal projection is thus a special case of a parallel projection in which the projection direction is the same as the normal direction of the plane.

A “relative unit radius” in the sense of the present invention describes a point or a particularly cylindrical plane at a defined distance from the axis of rotation in a standardized manner, which leads to improved comparability between different fan impellers.

"Aperiodic" in the sense of the present invention is in particular a shape which extends asymmetrically over the relative unit radius, that is to say, in other words, no axis of symmetry can be found which _defines the course of the relative position of the front edge POS rel_VK (t) and / or _divides the course of the relative position of the rear edge POS rel_HK (t) into two identical sub-functions. In other words: The course of the relative position of the front edge POS _{rel_VK} (t) and / or the course of the relative position of the rear edge POS _{rel_HK} (t) is not a function whose function values are repeated at regular intervals.

"Wavy" shape in the sense of the present invention is characterized in particular by the fact that the second derivative of the underlying function is always continuous.

In other words, the basic idea of the present invention is to give the leading edge and / or the trailing edge an aperiodically wavy shape, which leads to a unique design of the airfoil, as can be seen from the edge geometry (course of the relative position of the leading or trailing edge) is described. In this form according to the invention lies the key to increased air performance or to the power savings described above.

_{According to the} invention, the relative position of the leading edge POS rel_VK (t) is related to a third point which, viewed in the direction of rotation of the fan wheel, is the foremost point at the transition from the hub pot to the blade and / or the relative position of the trailing edge POS _{rel_HK} (t) is to one referring back to the fourth point, which, viewed in the direction of rotation of the fan wheel, is the rearmost point at the transition from the hub pot to the blade. This is particularly advantageous because in this way the relative position of the front and / or rear edge is referred back to a defined point in order to be able to determine an absolute position depending on the third and / or fourth point from the relative position.

According to the invention, the fan wheel has one or more blades that are sickled backwards when viewed in the direction of rotation. This is particularly important because for fan impellers with forward and backward sickle blades there are fundamentally different aerodynamic conditions which, among other things, have a significant influence on the conveyed air volume flow. Backward sickle in the sense of the present invention means in particular that the tip of the airfoil with the outer radius R _a , viewed in the direction of rotation, lags behind the center of the airfoil.

According to the invention, the fan wheel has an at least substantially circular outer ring which connects the blade tips of the blades to one another. This is particularly advantageous because in this way an increased mechanical strength of the fan wheel is achieved and a defined, at least essentially constant, gap is provided between a frame ring and the outer ring, which in turn leads to advantageous aerodynamic and / or acoustic effects.

_{According to the} invention, the course of the relative position of the trailing edge POS rel_HK (t) is in the range from 80% to 100%, in particular 90% to 100%, in particular 92.5% to 97.5%, of the relative unit radius t (r) of the blade ( 30) has a maximum, especially a local one. This is particularly advantageous since extensive experimental studies have shown that a, in particular a local, maximum in the specified area contributes a substantial proportion to the increase in the air volume flow.

_{According to the} invention, the course of the relative position of the leading edge POS rel_VK (t) in the range from 80% to 100%, in particular 90% to 100%, in particular 92.5% to 97.5%, of the relative unit radius t (r) of the blade ( 30) has an, in particular local, minimum. This is particularly advantageous since extensive experimental studies have shown that a, in particular a local, minimum in the specified area contributes a substantial proportion to the increase in the air volume flow.

According to a further embodiment of the present invention, the profile of the relative position of the trailing edge POS _{rel_HK} (t) in the y direction has no or at most one low point after the, in particular local, maximum. This is particularly advantageous because in this way the fan wheel runs out at least essentially in a straight line, since extensive tests have shown that further waves after the, in particular local, maximum do not achieve any further significant power savings.

According to a further embodiment of the present invention, the profile of the relative position of the leading edge POS _{rel_VK} (t) in the y direction after the, in particular local, minimum has no or at most one high point. This is particularly advantageous because in this way the fan wheel runs out at least essentially in a straight line, since extensive tests have shown that further shafts after the, in particular local, minimum do not achieve any further significant power savings.

According to a further embodiment of the present invention, the profile of the relative position of the front edge POS _{rel_VK} (t) and the profile of the relative position of the rear edge POS _{rel_HK} (t) are at least essentially axially symmetrical to one another, in particular the rear edge POS _{rel_HK} (t) runs around in an area a curve of +/- 20%, in particular +/- 10%, of the value of the relative position of the front edge POS _{rel_VK} (t), which is geometrically exactly mirrored on the axis of symmetry. In particular, the axis of symmetry corresponds to an especially horizontal straight line with the following property: $${\mathit{POS}}_{\mathit{rel}}\left(t\right)=0$$

This is particularly advantageous since extensive tests have shown that an at least essentially axially symmetrical profile of the front and rear edges with respect to one another achieves particularly positive results.

In other words, a curved pivot axis through the blade runs centrally or slightly eccentrically, e.g. at 40% of the blade extension in the direction of rotation, around which incremental disks of the blade, which are perpendicular to the pivot axis, are individually aligned. Thus, via the pivot axis, there is a functional relationship between the course of the relative position of the front edge POS _{rel_VK} (t) and the course of the relative position of the rear edge POS _{rel_HK} (t).

wobei gilt:

• t ₀∈[0;0,5], insbesondere t ₀∈[0;0,25], insbesondere t ₀∈[0;0,1]
• N∈[1;8], insbesondere N∈[2;5], insbesondere N∈[2;4]
• a∈[-1,5;1,5], insbesondere a∈[-1,0;1,0], insbesondere a∈[-0,5;0,5]
• A ₁∈[-10;10], insbesondere A ₁∈[-8;8], insbesondere A ₁∈[-5;5]
• A ₂∈[-10;10], insbesondere A ₂∈[-8;8], insbesondere A ₂∈[-5;5]
• A ₃∈[-10;10], insbesondere A ₃∈[-8;8], insbesondere A ₃∈[-5;5]; und
• A ₄∈[-10;10], insbesondere A ₄∈[-8;8], insbesondere A ₄∈[-5;5].

According to a further embodiment of the present invention, the course of the relative position of the front edge POS _{rel_VK} (t) as a function of the relative unit radius t (r) fulfills the following condition: $${\mathit{POS}}_{\mathit{rel}\_\mathit{VK}}\left(t\right)=\frac{-\left({\mathrm{A.}}_1{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}}^2+{\mathrm{A.}}_2\mathrm{<figure-callout\; id="2"\; label="t\; cos"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}\right)\cos \left[2\mathit{\pi N}\left(a\left(1-t\right)+1\right)\left(t+{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0006.png,imgf0007.png"\; state="\{\{state\}\}">t</figure-callout>}}_0\right)\right]+{\mathrm{A.}}_{3}t+{\mathrm{A.}}_{\mathrm{4th}}}{{\mathrm{R.}}_a-{\mathrm{R.}}_i}$$

where:

• t ₀ ∈ [0; 0.5], in particular t ₀ ∈ [0; 0.25], in particular t ₀ ∈ [0; 0.1]
• N ∈ [1; 8], especially N ∈ [2; 5], especially N ∈ [2; 4]
• a ∈ [-1.5; 1.5], especially a ∈ [-1.0; 1.0], especially a ∈ [-0.5; 0.5]
• A ₁ ∈ [-10; 10], especially A ₁ ∈ [-8; 8], especially A ₁ ∈ [-5; 5]
• A ₂ ∈ [-10; 10], especially A ₂ ∈ [-8; 8], especially A ₂ ∈ [-5; 5]
• A ₃ ∈ [-10; 10], in particular A ₃ ∈ [-8; 8], in particular A ₃ ∈ [-5; 5]; and
• A ₄ ∈ [-10; 10], in particular A ₄ ∈ [-8; 8], in particular A ₄ ∈ [-5; 5].

t ₀ describes an offset of the relative unit radius for setting the apex on the hub cup, N the number of oscillations over the axial unit radius, a an oscillation _{coefficient for scaling the wavelength and setting the position of the, in particular local, minimum, A 1} a quadratic polynomial coefficient, A _{2 is} a linear polynomial coefficient, A _{3 is} a coefficient of the axial threading, ie to set the linear course of the leading edge from the hub cup to the blade tip or to the outer ring and A _{4 is} a relative base deflection ("start" deflection) of the leading edge on the hub cup. The above-mentioned function describes the aperiodically wavy shape of the course of the relative position of the leading edge POS _{rel_vK} (t). With the help of the specified parameters, it is possible to adapt the course of the relative position of the front edge POS _{rel_VK} (t) to the external conditions in the course of the fan wheel design in order to achieve advantageous power savings or an equivalent increase in air volume.

wobei gilt:

• t ₀∈[0; 0,5], insbesondere t ₀∈[0;0,25], insbesondere t ₀∈[0;0,1]
• N∈[1;8], insbesondere N∈[2;5], insbesondere N∈[2;4]
• a∈[-1,5;1,5], insbesondere a∈[-1,0;1,0], insbesondere a∈[-0,5;0,5]
• A ₁∈[-10;10], insbesondere A ₁∈[-8;8], insbesondere A ₁∈[-5;5]
• A ₂∈[-10;10], insbesondere A ₂∈[-8;8], insbesondere A ₂∈[-5;5]
• A ₃∈[-10;10], insbesondere A ₃∈[-8;8], insbesondere A ₃∈[-5;5]; und
• A ₄∈[-10;10], insbesondere A ₄∈[-8;8], insbesondere A ₄∈[-5;5].

According to a further embodiment of the present invention, the course of the relative position of the rear edge POS _{rel_HK} (t) as a function of the relative unit radius t (r) fulfills the following condition: $${\mathit{POS}}_{\mathit{rel}\_\mathit{HK}}\left(t\right)=\frac{\left({\mathrm{A.}}_1{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}}^2+{\mathrm{A.}}_2\mathrm{<figure-callout\; id="2"\; label="t\; cos"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}\right)\cos \left[2\mathit{\pi N}\left(a\left(1-t\right)+1\right)\left(t+{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0006.png,imgf0007.png"\; state="\{\{state\}\}">t</figure-callout>}}_0\right)\right]+{\mathrm{A.}}_{3}t+{\mathrm{A.}}_{\mathrm{4th}}}{{\mathrm{R.}}_a-{\mathrm{R.}}_i}$$

where:

• t ₀ ∈ [0; 0.5], in particular t ₀ ∈ [0; 0.25], in particular t ₀ ∈ [0; 0.1]
• N ∈ [1; 8], especially N ∈ [2; 5], especially N ∈ [2; 4]
• a ∈ [-1.5; 1.5], especially a ∈ [-1.0; 1.0], especially a ∈ [-0.5; 0.5]
• A ₁ ∈ [-10; 10], especially A ₁ ∈ [-8; 8], especially A ₁ ∈ [-5; 5]
• A ₂ ∈ [-10; 10], especially A ₂ ∈ [-8; 8], especially A ₂ ∈ [-5; 5]
• A ₃ ∈ [-10; 10], in particular A ₃ ∈ [-8; 8], in particular A ₃ ∈ [-5; 5]; and
• A ₄ ∈ [-10; 10], in particular A ₄ ∈ [-8; 8], in particular A ₄ ∈ [-5; 5].

t ₀ describes an offset of the relative unit radius for setting the apex on the hub cup, N the number of oscillations over the axial unit radius, a an oscillation _{coefficient for scaling the wavelength and setting the position of the, in particular local, maximum, A 1} a quadratic polynomial coefficient, A ₂ a linear polynomial coefficient, A ₃ a coefficient of the axial threading, ie for setting the linear course of the trailing edge from the hub cup to the blade tip or to the outer ring and A ₄ a relative base deflection ("start" deflection) of the trailing edge on the hub cup. The above-mentioned function describes the aperiodically wavy shape of the course of the relative position of the rear edge POS _{rel_HK} (t). With the help of the specified parameters, it is possible to adapt the course of the relative position of the rear edge POS _{rel_HK} (t) to the external conditions in the course of the fan wheel design in order to achieve an advantageous power saving or an equivalent increase in air volume.

The fan wheel according to the invention according to one of the embodiments described here is intended in particular for use in connection with a fan frame with front struts, i.e. the struts are in front of the fan wheel as seen in the main flow direction.

Another aspect of the present invention relates to a cooling fan module, in particular for a motor vehicle, having a fan frame, a fan wheel recess which is formed in the fan frame, the fan wheel recess being delimited by a frame ring, a motor holder which is arranged inside the fan wheel recess and which over Struts is mechanically connected to the fan frame, a motor, in particular an electric motor, which is at least partially held in the motor holder, and a fan wheel which is arranged in the fan wheel recess and which is driven in rotation by the motor, the fan wheel according to one embodiment of the present Invention is formed.

A "cooling fan module" within the meaning of the present invention is in particular an assembly which, viewed in the direction of flow, is arranged upstream or downstream of a radiator of a vehicle and which is provided, in particular designed, to generate an air volume flow which extends through or around the radiator extends around the cooler, the air volume flow absorbing thermal energy from the cooler.

A “fan frame” within the meaning of the present invention is in particular a frame in which the fan wheel is held and itself is in turn preferably arranged, in particular fastened, on or in the vicinity of a cooler. A fan frame in the sense of the present invention preferably has a plastic material, in particular a plastic compound, in particular the fan frame is formed from this. Additionally and / or alternatively, the fan shroud has 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 therefrom. 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 cooling 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 implemented 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 and electrically and / or electronically connect a motor holder, which is also arranged in the fan wheel recess, to the fan frame. According to the present invention, the fan wheel recess is delimited by a frame ring.

A "frame ring" within the meaning of the present invention delimits the fan wheel recess in a plane perpendicular to the axis of rotation of the fan wheel, the plane in particular being at least essentially identical to the direction in which the fan frame extends. The frame ring can either be formed by an edge of the fan wheel recess and / or have a cylinder surface which expands in the axial direction and which is preferably formed in one piece with the fan frame.

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 counteracting the fan wheel. According to one embodiment, the motor holder is an at least substantially annular structure in which the motor is held. This is particularly advantageous since in this way an advantageous flow of cooling air through the motor is not impaired.

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

A “motor” within the meaning 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 self-sufficiently except for the supply of energy, that is to say 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 (electrical machine) which converts electrical power into mechanical power, in particular into torque. The term electric motor in the context 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 since electrical energy represents a form of energy that can be easily transmitted in comparison to mechanical or chemical energy, with which the required torque for driving the fan wheel is provided.

For the advantages of a cooling fan module configured in this way, reference is made to the above statements in order to avoid repetition.

According to one embodiment of the present invention, the struts of the cooling fan module are arranged in front of the fan wheel, viewed in the direction of flow. This is particularly relevant because front and rear struts lead to aerodynamic framework conditions that are significantly different from one another and the fan wheel described here can be used particularly advantageously with front struts, as extensive tests have shown.

Another aspect of the present invention relates to the use of a fan wheel of the type described here or a cooling fan module of the type described here in a motor vehicle. This is particularly important since the type of fan wheel described here comes into play in a particularly advantageous manner with the external conditions at the installation site.

Fig. 1A

ein Lüfterrad aus dem Stand der Technik in einer perspektivischen Darstellung mit Blick auf die Oberseite;

Fig. 1B

eine Vorderansicht auf ein Schaufelblatt des bekannten Lüfterrades der Fig. 1A mit Blickrichtung aus der Referenzebene in einer perspektivischen Darstellung, wobei die Oberseite des Lüfterrades nach unten weist;

Fig. 2A

ein Lüfterrad nach einer Ausführungsform der vorliegenden Erfindung in einer perspektivischen Darstellung mit Blick auf die Oberseite;

Fig. 2B

eine Vorderansicht auf ein Schaufelblatt des Lüfterrades der Fig. 2A mit Blickrichtung aus der Referenzebene in einer perspektivischen Darstellung, wobei die Oberseite des Lüfterrades nach unten weist;

Fig. 3

ein Lüfterrad aus dem Stand der Technik in einer perspektivischen Darstellung zur Beschreibung einer Referenzebene;

Fig. 4

den Verlauf der Relativposition der Vorderkante POSrel_VK(t) und der Relativposition der Hinterkante POSrel_HK(t) über den relativen Einheitsradius eines Lüfterrades gemäß einer Ausführung der vorliegenden Erfindung;

Fig. 5

einen Vergleich eines vorbekannten Lüfterrades mit einem Lüfterrad nach einer Ausführung der vorliegenden Erfindung; und

Fig. 6

ein Kühlerlüftermodul mit dem Lüfterrad gemäß der vorliegenden Erfindung gemäß dem zweiten Aspekt der vorliegenden Erfindung.

Further advantageous developments of the present invention emerge from the subclaims and the following description of preferred embodiments. This shows, partly schematically:

Figure 1A

a fan wheel from the prior art in a perspective view with a view of the top;

Figure 1B

a front view of a blade of the known fan wheel of Figure 1A with the direction of view from the reference plane in a perspective illustration, the top of the fan wheel pointing downwards;

Figure 2A

a fan wheel according to an embodiment of the present invention in a perspective view with a view of the top;

Figure 2B

a front view of a blade of the fan wheel Figure 2A with the direction of view from the reference plane in a perspective illustration, the top of the fan wheel pointing downwards;

Fig. 3

a fan wheel from the prior art in a perspective illustration for describing a reference plane;

Fig. 4

the course of the relative position of the front edge POSrel_VK (t) and the relative position of the rear edge POSrel_HK (t) over the relative unit radius of a fan wheel according to an embodiment of the present invention;

Fig. 5

a comparison of a previously known fan wheel with a fan wheel according to an embodiment of the present invention; and

Fig. 6

a cooling fan module with the fan wheel according to the present invention according to the second aspect of the present invention.

Figure 1A shows a fan wheel 1 from the prior art in a perspective view with a view of the top and Figure 1B FIG. 11 shows a front view of a blade 30 of the known fan wheel of FIG Figure 1A with the direction of view from the reference plane in a perspective illustration, the top (corresponds to the suction side) of the fan wheel 1 pointing downwards.

The fan wheel 1 has according to the Figure 1A , 1B , 2A , 2 B and 3 a hub pot 10 that is rotationally symmetrical about an axis of rotation R. A plurality of impeller blades 30 are arranged on the hub pot 10 and extend from a cylindrical outer wall 12 of the hub pot 10 extend outward in the radial direction. A direction of rotation D is in the Figure 1A and 2A indicated by an arrow. Accordingly, the direction of rotation is counterclockwise. A main flow direction of the conveyed air is marked with HSR. The fan wheel 1 has an at least substantially circular outer ring 20 which connects the blade tips of the blade blades 30 to one another.

Regarding the Figure 1B (and the Figure 2B ) it should be noted that the position of the axis of rotation R with regard to its distance from the cylindrical outer wall 12 of the hub cup 10 or the inner edge of the blade 30 (identified by points P3 and P4) is not to be seen as true to scale, i.e. the orientation is binding, the situation, however, is not.

Like that Figure 1A and 1B It can be seen that the airfoils 30 according to the prior art have flat or curved leading edges VK and flat or curved trailing edges HK in an orthogonal projection.

Figure 2A shows a fan wheel 1 according to an embodiment of the present invention in a perspective illustration and Figure 2B a front view of a blade 30 of the fan wheel of FIG Figure 2A with viewing direction from the reference plane E_REF in a perspective representation.

In comparison to designs of a fan wheel 1 according to the prior art (see Figures 1A and 1B ) has the fan wheel 1 according to an embodiment of the present invention according to the Figure 2A , 2 B Airfoil blades 30 with an aperiodically undulating trailing edge HK.

With regard to the perspective of the sectional view, refer to the following comments Fig. 3 referenced.

Fig. 3 shows a fan wheel 1 from the prior art in a perspective illustration for describing a reference plane E_REF.

In the following, the level of observation for describing the front edge VK and the rear edge HK is to be defined. This in Fig. 3 The fan wheel shown does not have an airfoil geometry according to the invention, which is not relevant for the description of the reference plane E_REF, since the explanations in this regard also apply in the same way to embodiments according to the invention.

Starting from the axis of rotation R, a reference straight line G_REF is defined by a first point P1 on the axis of rotation R of the fan wheel 1, a radial extension E through the first point P1 and perpendicular to the axis of rotation R and a second point P2, which has an arc-shaped edge at the transition divided from the hub pot 10 to the blade 30 into two equally long sections. In other words: the radius is determined which runs through the point P2. Point P2 represents the midpoint of the transition edge from hub cup 10 to blade 30, in particular the edge of blade 30 facing the pot bottom Auxiliary radius runs through P1 and a third point P3 of the transition edge between the cylindrical outer wall and the airfoil and a second auxiliary radius which runs through a fourth point P4 of the transition edge from the hub pot 10 to the airfoil 30 and from this angle which is enclosed between the two auxiliary radii , the bisector is formed. The point at which said bisector intersects the cylindrical outer wall 12, in particular on an outer side thereof, is P2. Starting from G_REF, a reference plane E_REF is defined by a straight line shifted parallel to the axis of rotation R and a straight line shifted parallel to the reference straight line G_REF, the shift being such that it is located completely in front of the blade 30 when viewed in the direction of rotation D of the fan wheel 1. An orthogonal projection of the front edge VK of the airfoil 10 and an orthogonal projection of the rear edge HK of the airfoil 10 are shown on the reference plane E_REF. The direction of view B shows how in the Figure 1B and 2 B a blade segment of the fan wheel 1 is viewed in each case.

A coordinate system consisting of the z-axis and y-axis is set up in the reference plane E_REF. _{This is decisive} for the description of the course of the relative position of the front edge POS rel_VK (t) and the course of the relative position of the rear edge POS _{rel_HK} ( t ). The z-axis is defined by an orthogonal projection of the axis of rotation R in the reference plane E_REF, which is shifted in a second step in the reference plane E_REF starting from the orthogonal projection of the axis of rotation R around an outer radius R _{i of} the hub pot 10 in a parallel outward radial direction. In other words: The orientation of the z-axis is unchanged, but is shifted in parallel in two steps, namely once by the orthogonal projection onto the reference plane E_REF and then by the shift in the reference plane E_REF by R _i . This means that the z-axis runs through the orthogonal projection from P2 to E_REF. The y-axis is defined by an orthogonal projection of the radial extension E in the reference plane E_REF. The origin this yz coordinate system is defined by the intersection of the two axes.

wobei

Ri

ein Außenradius des Nabentopfes 10 ist, was insbesondere wenigstens im Wesentlichen einem Innenradius des Schaufelblattes 30 entspricht;

Ra

ein Außenradius des Schaufelblattes 30 ist; und

r

der Abstand zwischen der Rotationsachse R und der zu betrachtenden Schnittebene S, welche im Abstand r von der Rotationsachse R auf der zugehörigen Referenzgerade G_REF senkrecht steht, wobei r∈[Ri;Ra].

A relative unit radius t (r) is plotted on the y-axis, which is defined as follows: $$t\left(r\right)=\frac{r-{\mathrm{R.}}_i}{{\mathrm{R.}}_a-{\mathrm{R.}}_i}$$

whereby

Ri

is an outer radius of the hub pot 10, which in particular corresponds at least substantially to an inner radius of the airfoil 30;

Ra

is an outer radius of the airfoil 30; and

r

the distance between the axis of rotation R and the cutting plane S to be considered, which is perpendicular to the associated reference straight line G_REF at a distance r from the axis of rotation R, where r ∈ [ Ri ; Ra ] .

Fig. 4 shows the course of the relative position of the front edge POS _{rel_VK} (t) and the relative position of the rear edge POS rel_HK (t) _{over the relative unit radius of} a fan wheel according to an embodiment of the present invention.

The horizontal axis corresponds to the y-axis described above and the vertical axis corresponds to the z-axis described above. The relative unit radius t (r) is plotted on the horizontal axis.

The profile of the relative position of the front edge POS _{rel_VK} (t) and the profile of the relative position of the rear edge POS _{rel_HK} (t) are each plotted in standardized form on the vertical axis.

und die Relativposition der Hinterkante POS_{rel_HK}(t) ergibt sich durch $${\mathit{POS}}_{\mathit{rel}\_\mathit{HK}}\left(t\right)=\frac{\left(A_1{t}^2+A_{2}t\right)\cos \left[2\mathit{\pi N}\left(a\left(1-t\right)+1\right)\left(t+t_0\right)\right]+A_{3}t+A_4}{R_a-R_i}$$

wobei jeweils t₀ einen Offset des relativen Einheitsradius zur Einstellung des Scheitelpunktes am Nabentopf, N die Anzahl der Schwingungen über den axialen Einheitsradius, a einen Schwingungskoeffizienten zur Skalierung der Wellenlänge und der Einstellung der Lage des , insbesondere lokalen, Extrempunkts (d.h. für die Vorderkante: Minimum; für die Hinterkante: Maximum), A₁ einen quadratischen Polynomkoeffizienten, A₂ einen linearen Polynomkoeffizienten, A₃ einen Koeffizienten der axialen Auffädelung, d.h. zur Einstellung des linearen Verlaufs der Vorder- bzw. Hinterkante vom Nabentopf zur Schaufelblattspitze bzw. zum Außenring und A₄ eine relative Basisauslenkung ("Start"-Auslenkung) der Vorder- bzw. Hinternkante am Nabentopf beschreibt. Die oben genannten Funktionen beschreiben die aperiodisch wellige Form des Verlaufs der Relativposition der Vorderkante POS_{rel_VK}(t) sowie der Hinterkante POS_{rel_HK}(t). The relative position of the front edge POS _{rel_VK} (t) results from $${\mathit{POS}}_{\mathit{rel}\_\mathit{VK}}\left(t\right)=\frac{-\left({\mathrm{A.}}_1{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}}^2+{\mathrm{A.}}_2\mathrm{<figure-callout\; id="2"\; label="t\; cos"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}\right)\cos \left[2\mathit{\pi N}\left(a\left(1-t\right)+1\right)\left(t+{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0006.png,imgf0007.png"\; state="\{\{state\}\}">t</figure-callout>}}_0\right)\right]+{\mathrm{A.}}_{3}t+{\mathrm{A.}}_{\mathrm{4th}}}{{\mathrm{R.}}_a-{\mathrm{R.}}_i}$$

and the relative position of the rear edge POS _{rel_HK} (t) is given by $${\mathit{POS}}_{\mathit{rel}\_\mathit{HK}}\left(t\right)=\frac{\left({\mathrm{A.}}_1{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}}^2+{\mathrm{A.}}_2\mathrm{<figure-callout\; id="2"\; label="t\; cos"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}\right)\cos \left[2\mathit{\pi N}\left(a\left(1-t\right)+1\right)\left(t+{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0006.png,imgf0007.png"\; state="\{\{state\}\}">t</figure-callout>}}_0\right)\right]+{\mathrm{A.}}_{3}t+{\mathrm{A.}}_{\mathrm{4th}}}{{\mathrm{R.}}_a-{\mathrm{R.}}_i}$$

where t _{0 is} an offset of the relative unit radius for setting the apex on the hub cup, N is the number of oscillations over the axial unit radius, a is an oscillation coefficient for scaling the wavelength and setting the position of the, in particular local, extreme point (i.e. for the leading edge: Minimum; for the trailing edge: maximum), A ₁ a quadratic polynomial coefficient, A ₂ a linear polynomial coefficient, A ₃ a coefficient of the axial threading, ie for setting the linear course of the leading or trailing edge from the hub cup to the blade tip or to the outer ring and A _{4 describes} a relative base deflection ("start" deflection) of the front or rear edge on the hub cup. The functions mentioned above describe the aperiodically wavy shape of the course of the relative position of the front edge POS _{rel_VK} (t) and the rear edge POS _{rel_HK} (t).

It can be seen that the course of the relative position of the rear edge POS _{rel_HK} (t) is in the range from 80% to 100%, in particular 90% to 100%, in particular 92.5% to 97.5%, of the relative unit radius t (r ) of the blade (30) has an, in particular local, maximum and the course of the relative position of the leading edge POS _{rel_VK} (t) in the range from 80% to 100%, in particular 90% to 100%, in particular 92.5% to 97.5 %, of the relative unit radius t (r) of the airfoil (30) has an, in particular local, minimum.

Like the exemplary embodiment of Fig. 4 It can also be seen that the course of the relative position of the trailing edge POS _{rel_HK} (t) in the y direction after the, in particular local, maximum has no or at most one low point and / or the course of the relative position of the leading edge POS _{rel_VK} (t) in y -Direction after the, in particular local, minimum no or at most one high point.

Again Fig. 4 It can also be seen that the course of the relative position of the front edge POS _{rel_VK} (t) and the course of the relative position of the rear edge POS _{rel_HK} (t) are at least essentially axially symmetrical to one another, in particular the rear edge POS _{rel_HK} (t) runs in an area around one geometrically clearly determined course of a mirrored curve of +/- 20%, in particular +/- 10%, of the value of the relative position of the leading edge POS _{rel_VK} (t).

wobei gilt:

• t₀ ∈[0;0,5]
• N∈[1;8]
• a∈[-1,5;1,5]
• A ₁∈[10;10]
• A ₂∈[-10;10]
• A ₃∈[-10;10] und
• A ₄∈[-10;10] .

The course of the relative position of the leading edge POS _{rel_VK} (t) of the exemplary embodiment of FIG Fig. 4 the following condition follows, depending on the relative unit radius t (r): $${\mathit{POS}}_{\mathit{rel}\_\mathit{VK}}\left(t\right)=\frac{-\left({\mathrm{A.}}_1{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}}^2+{\mathrm{A.}}_2\mathrm{<figure-callout\; id="2"\; label="t\; cos"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}\right)\cos \left[2\mathit{\pi N}\left(a\left(1-t\right)+1\right)\left(t+{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0006.png,imgf0007.png"\; state="\{\{state\}\}">t</figure-callout>}}_0\right)\right]+{\mathrm{A.}}_{3}t+{\mathrm{A.}}_{\mathrm{4th}}}{{\mathrm{R.}}_a-{\mathrm{R.}}_i}$$

where:

• t ₀ ∈ [0; 0.5]
• N ∈ [1; 8]
• a ∈ [-1.5; 1.5]
• A ₁ ∈ [10; 10]
• A ₂ ∈ [-10; 10]
• A ₃ ∈ [-10; 10] and
• A ₄ ∈ [-10; 10].

wobei gilt:

• t ₀∈[0;0,5]
• N∈[1;8]
• a∈[-1,5;1,5]
• A ₁∈[-10;10]
• A ₂∈[-10;10]
• A ₃∈[-10;10] und
• A ₄∈[-10;10]

The course of the relative position of the rear edge POS _{rel_HK} (t) of the exemplary embodiment of FIG Fig. 4 the following condition follows, depending on the relative unit radius t (r): $${\mathit{POS}}_{\mathit{rel}\_\mathit{HK}}\left(t\right)=\frac{\left({\mathrm{A.}}_1{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}}^2+{\mathrm{A.}}_2\mathrm{<figure-callout\; id="2"\; label="t\; cos"\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">t</figure-callout>}\right)\cos \left[2\mathit{\pi N}\left(a\left(1-t\right)+1\right)\left(t+{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0006.png,imgf0007.png"\; state="\{\{state\}\}">t</figure-callout>}}_0\right)\right]+{\mathrm{A.}}_{3}t+{\mathrm{A.}}_{\mathrm{4th}}}{{\mathrm{R.}}_a-{\mathrm{R.}}_i}$$

where:

• t ₀ ∈ [0; 0.5]
• N ∈ [1; 8]
• a ∈ [-1.5; 1.5]
• A ₁ ∈ [-10; 10]
• A ₂ ∈ [-10; 10]
• A ₃ ∈ [-10; 10] and
• A ₄ ∈ [-10; 10]

• t ₀=0,04
• N=4
• a=0
• A1=0
• A ₂=2
• A ₃=4 und
• A ₄=0.

The in Fig. 4 The illustrated course of the relative position of the front edge POS _{rel_VK} (t) results at least essentially, in particular absolutely, on the basis of the following parameters:

• t ₀ = 0.04
• N = 4
• a = 0
• A 1 = 0
• A ₂ = 2
• A ₃ = 4 and
• A ₄ = 0.

• t ₀=0,04
• N=4
• a=0
• A ₁=0
• A ₂=2
• A ₃=-5 und
• A ₄=0.

The in Fig. 4 The illustrated course of the relative position of the rear edge POS _{rel_HK} (t) results at least essentially, in particular absolutely, on the basis of the following parameters:

• t ₀ = 0.04
• N = 4
• a = 0
• A ₁ = 0
• A ₂ = 2
• A ₃ = -5 and
• A ₄ = 0.

the Fig. 5 shows a comparison of a previously known fan wheel 1 with a fan wheel 1 according to an embodiment of the present invention.

• eine Druckzahl ψ, welche als dimensionslose, von wirksamem Lüfterraddurchmesser D_W, der Luftdichte ρ und der Drehzahl n unabhängige Kennzahl das durch das Lüfterrad erzeugte Totaldruckgefälle Δp_t (setzt sich zusammen aus statischen und dynamischen Anteilen) zwischen stromaufwärtiger und stromabwärtiger Seite desselben beschreibt: $$\psi =\frac{2\mathrm{\Delta }{\mathrm{<figure-callout\; id="2"\; label="p\; t\; \pi "\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">p</figure-callout>}}_t}{{\pi }^{}}$$
  
• eine Leistungszahl λ, welche als dimensionslose, von wirksamem Lüfterraddurchmesser D_W, der Luftdichte ρ und der Drehzahl n unabhängige Kennzahl eine Eingangs-Leistung P_wel beschreibt: $$\lambda =\frac{8p_{\mathit{wel}}}{{\pi }^4{\mathit{\rho D}}_w^5{n}^3}$$
  
• Als Eingangs-Leistung P_wel wird hier die Wellenleistung des Elektromotors herangezogen, wobei entsprechende Verluste (Wärme, Reibung etc.) des Elektromotors nicht berücksichtigt sind.

Being represented:

• a pressure factor ψ, which is dimensionless _{and independent of the effective fan wheel diameter D W} , the air density ρ and the speed n The key figure describes the total pressure gradient Δ p _t (made up of static and dynamic components) between the upstream and downstream sides of the fan wheel: $$\psi =\frac{2\mathrm{\Delta }{\mathrm{<figure-callout\; id="2"\; label="p\; t\; \pi "\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">p</figure-callout>}}_t}{{\pi }^{}}$$
  
• a coefficient of performance λ, which describes an input power P _{wel as a dimensionless, independent of the effective fan wheel diameter D W} , the air density ρ and the speed n: $$\lambda =\frac{\mathrm{8th}{p}_{\mathit{wel}}}{{\pi }^{\mathrm{4th}}{\mathit{\rho D}}_w^5{n}^3}$$
  
• The shaft power of the electric motor is used here as the input power P _wel , with corresponding losses (heat, friction, etc.) of the electric motor not being taken into account.

The following is also shown:
a total efficiency η, which relates the input power P _wel with the generated total pressure gradient Δ p _t over the conveyed volume flow V̇. $$\eta =\frac{\mathrm{\Delta }{p}_{t}V}{p_{\mathit{wel}}}$$

A volume number ϕ is plotted on the x-axis of the diagram, which describes the conveyed volume flow V̇ _{as a dimensionless number independent of the effective fan wheel diameter D w and the speed n:} $$\phi =\frac{\mathrm{<figure-callout\; id="2"\; label="4th\; V\; \pi "\; filenames="imgf0007.png,imgf0008.png"\; state="\{\{state\}\}">4th</figure-callout>}V}{{\pi }^{}}$$

In other words: The specified key figures are de-dimensioned with the circle number π , the air density ρ in kg / m ³ , the effective diameter ( D _w = 2 R _a ) in m and the speed n in 1 / s. This means that it can be compared with fan impellers that are not identical in construction.

As can be seen, with almost the same performance (similar performance figure), a higher pressure figure (=> total pressure increase) is achieved, so that there is a significant increase in efficiency in the relevant volume figure range.

Fig. 6 shows a cooling fan module 100 with the fan wheel 1 according to the present invention according to the second aspect of the present invention.

The cooling fan module 100 has a fan frame 2, a fan wheel recess 40 being formed in the fan frame 2, which is delimited by a frame ring 42. A motor holder (covered by the hub cup 10) is arranged within the fan wheel recess 40 and is mechanically connected to the fan frame 2 via struts 44. A motor, in particular an electric motor, is at least partially held in the motor holder (also covered by the hub cup 10). A fan wheel 1 is arranged in the fan wheel recess 40 and is driven in rotation by the motor. The fan wheel 1 corresponds to an embodiment of a fan wheel 1 according to the present invention. For a detailed design of the fan wheel 1, reference is made to the above statements. The struts 44 are according to the embodiment of FIG Fig. 6 Arranged in front of the fan wheel, viewed in the direction of flow, the direction of flow being perpendicular to the figure Fig. 6 shows out.

Although exemplary embodiments have been explained in the preceding description, it should be pointed out that a large number of modifications are possible. In particular, such a design of the fan frame according to the invention is also suitable for dissipating waste heat from components of a purely electrically operated vehicle. It should also be pointed out that the exemplary designs are merely examples that are not intended to limit the scope of protection, the applications and the structure in any way. Rather, the preceding description provides a person skilled in the art with guidelines for the implementation of at least one exemplary embodiment, with various changes, in particular with regard to the function and arrangement of the described components, being able to be made without departing from the scope of protection as it emerges from the claims and these equivalent combinations of features results. <b> List of reference symbols </b> 1 Fan wheel 2 frame 10 Hub pot 12th (cylindrical) outer wall of the hub pot 10 20th Outer ring 30th Shovel blade 40 Fan wheel recess 42 Bezel ring 44 Striving 100 Cooling fan module HK Trailing edge VK Leading edge B. Direction of view D. Direction of rotation E. Radial extension E_REF Reference plane G_REF Reference line HSR Main flow direction P1 First point P2 Second point P3 third point P4 Fourth point POS _{rel_VK} ( t ) Relative position of the leading edge POS _{rel_HK} (t) Relative position of the trailing edge r Distance between axis of rotation R and cutting plane S R. Axis of rotation R _a Outer radius of the airfoil 30 R _i Outer radius of the hub cup 10 S. Cutting plane y y-axis z z-axis

Claims (9)

1. Fan wheel (1), in particular for a motor vehicle, comprising
   a hub pot (10), which in particular is rotationally symmetrical around an axis of rotation (R); and
   a plurality of blades (30) arranged on the hub pot (10) and extending radially outwardly from an, outer wall (12) of the hub pot (10) that is in particular at least substantially cylindrical,
   wherein each blade (30) has a leading edge (VK) and a trailing edge (HK), wherein for at least one blade (30), in particular some of the blades (30), in particular all of the blades (30), the following applies:

   a reference line (G_REF) is defined by:

   a first point (P1) on a rotation axis (R) of the fan wheel (1);

   a radial extension (E) through the first point (P1) and perpendicular to the rotation thing (R); and

   a second point (P2), which divides an arcuate edge at the transition from the hub pot (10) to the blade (30) into two sections of equal length,

   wherein a reference plane (E_REF) is defined by a line displaced parallel to the axis of rotation (R) and a line displaced parallel to the reference line (G_REF), the displacement being such that, viewed in the direction of rotation (D) of the fan wheel (1), it is located entirely in front of the blade (30),

   wherein an orthogonal projection of the leading edge (VK) of the blade (30) and an orthogonal projection of the trailing edge (HK) of the blade (30) are mapped in the reference plane (E_REF);

   wherein a z-axis is defined in the reference plane (E_REF) by an orthogonal projection of the rotation axis (R) in the reference plane (E_REF), which is displaced parallel outward in the radial direction in the reference plane (E_REF) starting from the orthogonal projection of the rotation axis (R) around an outer radius (Ri) of the hub pot (10)

   wherein a y-axis in the reference plane is defined by an orthogonal projection of the radial extension (E) in the reference plane (E_REF);

   wherein a relative unit radius t(r) is plotted on the y-axis, which is defined as follows: $$t\left(r\right)=\frac{r-R_i}{R_a-R_i}$$

   

   wherein

   R_i is an outer radius of the hub pot (10), which in particular corresponds at least substantially to an inner radius of the blade (30);

   R_a is an outer radius of the blade (30); and

   R is the distance between the axis of rotation (R) and the sectional plane (S) to be considered, which is at a distance r perpendicular from the axis of rotation (R) on the associated reference line (G_REF), wherein
   r∈[R_i ;R_a ]

   wherein a relative position of the leading edge POSrel_VK and a relative position of the trailing edge POS_{rel_HK} is plotted on the z-axis,

   wherein the course of the relative position of the leading edge POS_{rel_VK}(t) and the course of the relative position of the trailing edge POS_{rel_HK}(t) has an aperiodically wave-like shape,

   wherein the relative position of the leading edge POS_{rel_VK}(t) is referenced to a third point (P3), which, viewed in the direction of rotation (D) of the fan wheel (1), is the forward-most point at the transition from the hub pot (10) to the blade (30); and the relative position of the trailing edge POS_{rel_VK}(t) is referenced to a fourth point (P4), which, viewed in the direction of rotation (D) of the fan wheel (1), is the rearward-most point at the transition from the hub pot (10) to the blade (30),

   wherein the blade (30), viewed in the direction of rotation (D), is a backward-swept blade (30), such that, viewed in the direction of rotation, the tip of the blade lags the center of the blade with the outer radius (R_a).

   wherein the fan wheel (1) has an at least substantially circular outer ring (20) interconnecting blade tips of the blades (30),

   wherein the course of the relative position of the trailing edge POS_{rel_VK}(t) has a maximum in the range of 80% to 100% of the relative unit radius t(r) of the blade (30); and

   wherein the course of the relative position of the leading edge POS_{rel_VK}(t) has a minimum in the range of 80% to 100% of the relative unit radius t(r) of the blade (30).
2. Fan wheel according to one of the preceding claims, wherein.
   the course of the relative position of the trailing edge POS_{rel_HK}(t) has a maximum, in particular a local maximum, in the range from 90 % to 100 %, in particular 92.5 % to 97.5 %, of the relative unit radius t(r) of the blade (30).
3. Fan wheel according to the preceding claim, wherein
   the course of the relative position of the trailing edge POS_{rel_HK}(t) in the y-direction after the, in particular local, maximum has no or at most one low point.
4. Fan wheel according to one of the preceding claims, wherein
   the course of the relative position of the leading edge POS_{rel_VK}(t) and the course of the relative position of the trailing edge POS_{rel_HK}(t) are at least substantially axisymmetrical to one another, in particular the trailing edge POS_{rel_HK}(t) runs in a range around a geometrically unambiguously determined course of a mirrored curve of +/- 20 %, in particular +/- 10 %, of the value of the relative position of the leading edge POS_{rel_VK}(t).
5. Fan wheel according to one of the preceding claims, wherein
   the variation of the relative position of the leading edge POS_{rel_VK}(t) as a function of the relative unit radius t(r) satisfies the following condition: $${\mathit{POS}}_{\mathit{rel}\_\mathit{VK}}\left(t\right)=\frac{-\left(A_1{t}^2+A_{2}t\right)\cos \left[2\mathit{\pi N}\left(a\left(1-t\right)+1\right)\left(t+t_0\right)\right]+A_{3}t+A_4}{R_a-R_i}$$

   

   wherein the following applies:

   t ₀∈[0;0,5]

   N∈[1;8]

   a∈[-1,5;1,5]

   A ₁∈[-10;10]

   A₂∈[-10;10]

   A₃∈[-10;10] and

   A ₄∈[-10;10].
6. Fan wheel according to one of the preceding claims, wherein
   the course of the relative position of the trailing edge POS_{rel_HK}(t) as a function of the relative unit radius t(r) satisfies the following condition: $${\mathit{POS}}_{\mathit{rel}\_\mathit{HK}}\left(t\right)=\frac{\left(A_1{t}^2+A_{2}t\right)\cos \left[2\mathit{\pi N}\left(a\left(1-t\right)+1\right)\left(t+t_0\right)\right]+A_{3}t+A_4}{R_a-R_i}$$

   

   wherein the following applies:

   t ₀∈[0;0,5]

   N∈[1;8]

   a∈[-1,5;1,5]

   A ₁∈[-10;10]

   A ₂∈[-10;10]

   A ₃=[-10;10] and

   A ₄∈[-10;10].
7. Radiator fan module (100), in particular for a motor vehicle, comprising:

   a fan frame (2);

   a fan wheel recess (40) formed in the fan frame (2), wherein the fan wheel recess (40) is bounded by a frame ring (42);

   a motor holder, which is arranged inside the fan wheel recess (40) and which is mechanically connected to the fan frame (2) via struts (44);

   a motor, in particular an electric motor, which is at least partially held in the motor holder; and

   a fan wheel (1), which is arranged in the fan wheel recess (40) and which is rotationally driven by the motor,
   characterized in that

   the fan wheel (1) is formed according to one of the preceding claims.
8. Radiator fan module according to the preceding claim, wherein
   the struts (44) are arranged in front of the fan wheel (1) as seen in the direction of flow.
9. Use of a fan wheel according to one of claims 1 to 6 or a radiator fan module according to one of claims 7 or 8 in a motor vehicle.

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