DE102013114609A1 - Radial impeller for a drum fan and fan unit with such a radial impeller - Google Patents

Abstract

The invention relates to a radial impeller (10) with axial air inlet and air outlet over the impeller periphery, preferably for use in a helically configured housing (7), with a bottom disc (3) having an outer diameter (Da, BS), and with a concentric with the bottom plate (3) axially spaced cover plate (1), which for the axial air inlet has a circular suction opening (4) with an inner diameter (Di, DS), and with a plurality of between the bottom plate (3) and formed between two adjacent vanes (2) a flow channel (5) with a radially inner air inlet side (5a) and a radially outer air outlet side (5b) is - seen in the direction of travel (LR) of the radial impeller (10) - at least partially convex curved. In order to combine in such an impeller (10) the advantages of a drum rotor with those of an impeller with backward curved blades, it is proposed that the outer diameter (Da, BS) of the bottom disk (3) - based on the inner diameter (Di, DS) of the suction port (4) - at least 20% larger than the inner diameter (Di, DS) of the suction port (4) is that the cover plate (1) in the flow channel (5) forms a deck-side guide surface (8), and that in the direction of Inlet opening (4) opening angle (αDS), the between a tangent (T1) to the deck-side guide surface (8) at the inlet to the suction port (4) and a tangent (T2) to the deck-side guide surface (8) at the exit from the flow channel (5) is formed at its radially outer air outlet side (5b) is at least 30 °.

Description

The present invention relates to a radial impeller with axial air inlet and air outlet over the impeller circumference, preferably for use in a spirally designed housing, with a bottom plate, which has an outside diameter, and with a concentric with the bottom plate axially spaced cover plate, which for the axial air inlet has a circular suction opening with an inner diameter, and with a plurality of arranged between the bottom plate and the cover disc, forward curved, profiled blades, wherein between each two adjacent blades a flow channel with a radially inner air inlet side and a radially outer Air outlet side is formed, which - seen in the direction of the radial impeller - is curved convex. This channel curvature means that the suction-side surfaces of the blades-at least in some regions-are convex and their pressure-side surfaces-at least regionally-have a concave curvature.

Furthermore, the present invention relates to a fan unit, in particular a drum fan, with such a radial impeller. The term fan here fans are subsumed with a pressure ratio between the suction and discharge side in the range of 1.0 to 1.1 and blowers with a pressure ratio between the intake and pressure side in the range 1.1 to 3.0.

Today, radial impellers are preferably used where a high pressure build-up is to be achieved at a lower volume flow. With radial impellers, the entire flow of air delivered leaves the impeller at the outer diameter, it is possible to produce a higher kinetic energy of the air molecules and thus a higher pressure than an axial fan whose peripheral speed is limited at the wheel hub. The use of radial impellers is particularly effective when an air flow must be deflected by 90 ° from the axial in the radial direction, or if components, filters o. Ä. Impair a free air flow. The most common design is as a one-piece radial all-in-one fan, although there are also different engine / impeller combinations for applications where the air duct can be integrated into a unit for pressure build-up.

In the case of radial impellers, a distinction is made between impellers with forwardly curved blades in the running direction, those with rearwardly curved blades and those with radially ending blades. Forward - in the direction of rotation - curved blades cause the flow channel, which runs from a radially inner air inlet side to a radially outer air outlet side, - seen in the running direction of the radial impeller - is convexly curved. The suction-side surfaces of the blades are thus - at least partially - convex and their pressure-side surfaces - at least partially - concave curved. Radial impellers with forward curved blades allow a high swirl of the air flow and thus achieve a high energy conversion. The disadvantage, however, is a high dynamic pressure of the exiting air. This dynamic pressure must be converted into static pressure in a downstream diffuser, such as a volute casing. Radial impellers with forwardly curved vanes impart more swirl to the flow than radial impellers with backward-curved vanes. Thus, the speed required to achieve the same operating point is significantly lower for radial impellers with forward curved blades than for radial impellers with backward curved blades of the same size. The efficiency of radial impellers with backward curved blades is significantly higher than that of radial impellers with forward curved blades.

A special version of the radial fan is the drum fan. Drum fans are radial fans whose impellers are the same as a drum. H. the impeller width is relatively large compared to the wheel diameter. It may in particular be in the range between 40 and 80 percent, based on the outer diameter of the bottom disk. Such, also known under the name Scirocco runners for about 80 years, provided with forward curved blades runners are used in applications that require small radial dimensions. The ratio of the inner diameter of the cover disc to the outer diameter of the bottom disc of the original Scirocco rotor was 0.875.

Today's forward curved radial impellers, which are used in spiral-shaped housings as a drum rotor, are characterized by a high power density, ie by a high flow rate in a small space and good acoustic properties, in particular by a low noise level during operation from. However, the aerodynamic efficiency is relatively low due to detachments and vortices compared to backward curved wheels. Drum roller fans are used in the field of air conditioning and air conditioning in systems with a required pressure increase of preferably up to 4000 Pa and with flow rates up to 8 m ³ / s - related to a wheel diameter of one meter and a single-flow design.

For example, from the DE 10 2006 031 167 A1 known radial impeller of the type mentioned with axial air inlet and air outlet over the impeller circumference can be prevented or minimized by a strong profiling of the blades a separation in the flow channel between the blades. Profiling means that the thickness of the blades is variable over their Ersteckungsrichtung, in particular, the blades are considered to be highly profiled, if in them a so-called profile thickness ratio, ie a ratio of profile thickness to total profile length, greater than or equal to 0.15, in particular greater or equal to 0.2 and more preferably greater than or equal to 0.25. The profile thickness ratio is at most preferably 0.5, in particular 0.4 and particularly preferably 0.35. The non-figuratively shown in the above document cover plate is referred to there as a frame and is part of the spiral housing. A detachment on the cover plate is disadvantageously reinforced by the known blade profiling. An increase in the efficiency is thus possible by this measure only to a very limited extent.

The present invention is based on the object to provide a radial impeller of the type mentioned and a fan unit with such a radial impeller in which unite the advantages of a drum rotor with those of an impeller with backward curved blades, with which in particular an increase in efficiency while maintaining a high power density and low noise can be achieved.

According to the invention this is achieved in that the outer diameter of the bottom disc of the radial impeller - based on the inner diameter of the suction - at least 20% larger than the inner diameter of the suction port that the cover plate in the flow channel forms a deck-side guide surface, with a in the direction the inlet opening angle, which is formed between a tangent to the deck-side guide surface at the entrance to the suction port of the cover plate and a tangent to the deck-side guide surface at the exit from the flow channel at its radially outer air outlet side is at least 30 °.

A fan unit according to the invention is characterized in that the radial impeller according to the invention is arranged in a housing, in particular in a spiral-shaped housing.

By the invention, the advantage of previously known as drum rotor radial impellers can be maintained that they have a high power density and a low noise with low rotary sound overshoot compared to radial impellers with backward curved blades. The advantageously high power density is attributable to a high swirl supply of the flow through the forward curvature of the blades. In this case, a low noise is promoted by preferably high numbers of blades and preferably low speeds during operation. Both the forward curvature, and in particular a high number of blades prevent or at least reduce detachment on the blades and on the cover disk, but increase the frictional forces, which can lead to losses and a reduction in the efficiency. This can be effectively counteracted by the inventive geometric design of the radial impeller, which can be provided in a preferred embodiment, that the outer diameter of the bottom plate - based on the inner diameter of the intake of the cover plate - 50% larger, at most by more than 90% larger than the inner diameter of the cover plate is.

The inventive design of the deflection of the axial flow in the radial or diagonal direction can be prevented in particular a detachment of the cover plate, which can be detected by a so-called CFD flow simulation. CFD (Computational Fluid Dynamics) refers to a method established in fluid mechanics that aims to solve flow-mechanical problems iteratively with numerical methods and then to visualize the results, preferably through color representations. In this case, the Navier-Stokes equations used in fluid mechanics and describing momentum and mass conservation are modeled mathematically under specification of certain boundary conditions. This represents a cost-effective alternative to complex, for example in the wind tunnel experimental series of experiments and allows to analyze flow parameters that are not metrologically detectable, such as the turbulent kinetic energy, the vortex viscosity, etc.

To prevent detachment of the cover plate also contributes to a design of the cover plate with preferably relatively large axial width, after which the width of the cover plate can preferably occupy at least 30% of the total width of the impeller. Such a width dimensioning is considered to be synergistically effective in combination with the invention, since in conventional drum travelers with unprofiled blades no improvement can be achieved by this design.

At a given shaft power, the efficiency is determined by the volume flow and by the total pressure caused by the fan, from the product results in the flow rate, which is understood in accordance with the so-called Bernoulli equation under total pressure, the sum of static and dynamic pressure. The efficiency thus describes the ratio of the capacity to the power of a fan driving shaft and is based on the formula η = (V · Δp _t ) / P _w where η is the dimensionless efficiency, V is the volume flow in m ³ / s, Δp _{t is} the total pressure increase in Pa and P _{w is} the shaft power in W.

The combination of the feature "profiled blades" with the features of the fluidically designed according to the invention cover plate can significantly increase the efficiency. However, this is only possible if the outer diameter of the bottom plate - in contrast to the previous, known embodiments - at least 20% larger than the size of the suction opening defining inner diameter of the cover plate.

On the other hand, it is not possible with unprofiled blades, as they are also known from the prior art, even with the diameter ratio provided according to the invention and the minimum angle between the tangents of 30 ° to redirect the flow in the blade channel. Detachments are known to be lossy and result in poor impeller efficiency. Thus, it is even known to be assumed that a false flow at the blade inlet due to blades that are too steep can still be regarded as more favorable than an unstable detachment, which sets in with blade-congruent flow. By blade profiling, the flow despite blade-congruent flow, which means low impact losses at the blade inlet, are deflected in the design according to the invention provided cover and bottom disc free transfer in the blade channel.

A further increase in efficiency of a total blower with the radial impeller according to the invention can be achieved by selecting a width ratio of a housing width at the impeller outlet to impeller outlet width itself of at least 1.0 up to a maximum of 1.4.

With the invention, efficiencies in the range between 0.65 and 0.80, preferably even up to 0.90, can be achieved.

When a prior art backward-curved centrifugal fan is operated at the acoustically optimum operating point, ie at maximum efficiency, the total sound power level can be achieved with an accuracy of ± 4 dB according to the formula L _w = 37 + 10log (V) + 20 * log (Δp _t ) estimated. Here, L _{w is} the total sound power level in dB, V the volume flow in m ³ / s and Δp _t the total pressure increase in Pa. However, this formula is not applicable to the radial impeller according to the invention. In comparison with the values measured or obtained according to the above L _w formula for radial impellers according to the prior art, a radial impeller according to the invention, e.g. B. with an outer diameter of 170 mm, in the acoustically optimized operating range an improvement of more than 4 dB.

Under the coefficient of performance L, which is to be regarded as a measure of the power density, one understands according to the formula L = φ _r · Ψ the product of delivery number φ _r and pressure number Ψ. All sizes are dimensionless, with the delivery number φ _r according to the formula φ _r = (V × 60) / (b × π ² × D ² × n) is calculated and describes the ratio of the actual flow rate to the theoretically possible flow rate. The latter results from the product of the exit surface of the wheel and the peripheral speed. In the formula, φ _{r is} the delivery number, where the index r stands for "radial", V is again the volume flow in m ³ / s, D is the impeller outer diameter in m, which is determined by the outlet diameter D _{a, S of} the blades, b the outlet width of the impeller in m and n the speed in 1 / min.

The pressure number represents the ratio of the pressure level generated by the wheel to the back pressure of the peripheral speed and is calculated according to the formula Ψ = (Δp _t × 2 × 60 ² ) / (ρ × (D × π × n) ² ) calculated, where Ψ the dimensionless pressure, ρ the density in kg / m ³ , Δp _t the total pressure increase in P _{a, D} turn the determined by the outlet diameter D _{a, S of} the blades impeller outer diameter in m, and n the speed in 1 / min are.

With the invention, delivery numbers in the range of 0.6 to 1.0, preferably in the range of 0.6 to 0.8 and pressure numbers in the range of 2.2 to 3.2, preferably in the range of 2.8 to 3, 0, where the coefficient of performance may range from 0 to 1.5, preferably from 0 to 1.0.

In contrast to conventional drum travelers, in which in the installation situation of the impeller usually an axial distance in the range of a few millimeters between the nozzle and cover plate, in the inventive design of the cover additionally optionally advantageously also a nozzle-shaped design of the inlet and an axial immersion of the nozzle be provided in the cover plate. Thereby, the split flow can be directed in the same direction as the main volume flow entering through the suction port. The split flow then advantageously contributes to the stabilization of the deflection in the radial direction, as is known to occur only with radial wheels with backward curved blades.

Advantageous embodiments of the invention are contained in the subclaims and will be explained in more detail with reference to the embodiments illustrated in the accompanying drawings. Showing:

1 in an axially partially sectioned view, a preferred embodiment of a radial impeller according to the invention,

2 a view of one along the line II-II in 1 extending cross section of in 1 illustrated embodiment of the radial impeller according to the invention,

3 in a representation similar to in 1 but fully cut, the embodiment of a radial impeller according to the invention in the installed state in a fan unit according to the invention,

4 in an axial half section, a view of a second embodiment of a radial impeller according to the invention in a fan unit according to the invention,

5 in a view like in 4 , one opposite 3 simplified representation of the first embodiment of a radial impeller according to the invention in a fan unit according to the invention,

6 in a view like in 1 , An illustration of a second embodiment of a radial impeller according to the invention.

In the figures of the drawing, like parts or functionally identical parts are also identified by the same reference numerals. If certain, described and / or removable from the drawings features of the radial impeller or the fan unit according to the invention or its components are mentioned only in connection with the embodiments, but these are also independent of this embodiment as a single feature or even according to the invention in combination with other features of the embodiment of meaning and can be claimed as belonging to the invention.

As first off 1 and 2 shows, has an inventive radial impeller 10 a cover disk 1 , a plurality of forward curved profiled blades 2 and a bottom disk 3 on. The cover disk 1 forms a suction mouth and thus has a circular intake opening for an axial air inlet 4 with an inner diameter D _{i, DS} on. The bottom disk 3 has an outer diameter D _{a, BS} and is concentric with the cover plate 1 axially spaced from the cover plate 1 arranged.

The shovels 2 are located between the cover disk 1 and the bottom disk 3 , Between every two blades 2 is a flow channel 5 formed, seen in the direction LR of the radial impeller 10 Is convexly curved, and in which the flow in a direction S from a radially inner air inlet side 5a to a radially outer air outlet side 5b he follows. The at least partially convex curvature of the flow channel 5 - Seen in the direction LR of the radial impeller 10 - means that, like 2 shows a print page 2c the shovel 2 , which - seen in the direction LR of the radial impeller 10 - each under the shovel 2 is located, at least partially concave, and a suction side 2d the shovel 2 , which - seen in the direction LR of the radial impeller 10 - each on the blade 2 is at least partially convex curved.

The cover disk 1 , the shovels 2 and the bottom disk 3 can preferably be designed as a two-part, in particular two plastic injection molded parts, materially connected composite body.

Profiling of the blades 2 means that the profile thickness d _{S of} the blade 2 over whose length is not constant. Characteristic of the profiling of the blades 2 is a profile thickness ratio, which by the ratio V _P of maximum profile thickness d _S to the profile total length L _S (see 2 ) and should be at least 0.15, in particular at least 0.2 and particularly preferably at least 0.25, wherein the profile thickness ratio V _{P can be} at most 0.5, in particular 0.4 and particularly preferably 0.35. The position of the maximum profile thickness d _S can thereby preferably in the range of 5% to 75% of the total profile length L _S - from the air inlet side 5a Seen from - both lie and reduces from there, both in the direction of the leading edge 2a the shovel 2 towards, as well as in the direction of the trailing edge 2 B out. Through these, in particular streamlined, Profiling come the advantages described above to bear, but according to the invention without peeling phenomena of the flow on the cover plate 1 occur.

To form a fluidically favorable form can - like 2 illustrated - optionally be provided that each of the leading edges 2a and / or the trailing edges 2 B the blades 2 are rounded. Further, the blade shape optional or preferably descriptive features are a crescent-shaped, but asymmetrical cross-section of the blades 2 , an at least partially convex outer curvature of the suction side 2d , which is larger than the at least partially concave inner curvature of the pressure side 2c , and a teardrop shape with respect to the curved center axis through the blade 2 ,

An optimal number of blades in a characteristic way for a drum fan 2 is at least 19 and at most 54 and is preferably in the range of 22 to 46. High blade numbers may obstruct the flow channel 5 cause and reduce the maximum possible flow rate V. Also, the friction losses on the blade walls may increase, so that there is a decrease in the efficiency η.

As further out 3 , as well as out 4 and 5 , is apparent, is an inventive radial impeller 10 preferably for use in a fan unit according to the invention 20 certainly. In this fan unit according to the invention 20 can the radial impeller of the invention 10 preferably coaxial with an electric drive motor 6 be arranged and is located in a housing 7 in which - as in 3 shown - preferably around a spirally designed housing 7 can act.

In the fan unit according to the invention 20 In the illustrated embodiment, it is a blower with a radially curved forward wheel. It may preferably be a drum fan, for the further is also characteristic that in him the total width b _{ges of} the radial impeller 10 in the range of 25% to 70% based on the outer diameter D _{a, BS of} the bottom disk 3 lies. As 1 shows, this results in the total width b _tot as the sum of a width b _{DS of} the cover plate 1 and an impeller outlet width b ₂ on the radially outer air outlet side 5b of the flow channel 5 ,

According to the invention, it is provided that the outer diameter D _{a, BS of} the bottom disk 3 - Based on the inner diameter D _{i, DS of} the cover plate 1 - At least 20%, preferably by at least 50%, greater than the inner diameter D _{i, DS of} the cover plate 1 is. The cover disk 1 forms for the flow channel 5 a deck-side guide surface 8th out, with one in the direction of the inlet opening 4 opening angle α _DS , between a tangent T ₁ to the deck-side guide surface 8th at the entrance to the intake 4 the cover disk 1 and a tangent T ₂ to the deck-side guide surface 8th at the exit from the flow channel 5 on its radially outer air outlet side 5b is formed, at least 30 °. The maximum value of this angle can be at 90 °, preferably at 75 °. The tangent T ₁ runs in the first embodiment parallel to the longitudinal axis XX of the radial impeller 1 , In this way, according to the invention, such an aerodynamically favorable flow deflection from the axial in a radial or diagonal direction, that it comes to an increase in the efficiency η while maintaining the advantages of conventional drum travelers.

This is also the case when the tangent T ₁ from the parallel course to the longitudinal axis XX of the radial impeller 1 deviates by an angle value α _DS1 of up to ± 30 °, but preferably only up to ± 5 °, as the second embodiment according to 6 shows. A towards the entrance opening 4 opening angle, between the tangent T ₂ to the deck-side guide surface 8th at the exit from the flow channel 5 on its radially outer air outlet side 5b and the longitudinal axis XX of the radial impeller 10 is formed, is denoted by the reference numeral α _DS2 . For the invention claimed angle α _DS thus applies α _DS = α _DS2 - α _DS1 .

In analogy to the guide surface 8th on the cover disk 1 can also the bottom disk 3 in the flow channel 5 a bottom-side guide surface 9 in the flow channel 5 form.

The deck-side guide surface 8th and / or the bottom-side guide surface 9 of the flow channel 5 in particular, as in the drawing - except at the bottom plate 3 the execution in 4 - Shown to be executed curvature continuous, which counteracts the advantage of the formation of flow turbulence.

Instead of the above, measured axially in the direction of the longitudinal axis XX distance between the bottom plate 3 and cover disc 1 is in 1 . 2 and 5 in the flow channel 5 - Each designated by the reference numeral A - a shortest, preferably between the air inlet side 5a and air outlet side 5b of the flow channel 5 variable distance between bottom disc 3 and cover disc 1 located. For this distance A can be provided with advantage that he in the direction of S from the radially inner air inlet side 5a to the radially outer air outlet side 5b decreases, in particular taking into account by the number of blades 2 certain blade spacing such that also the cross section of the respective flow channel 5 rejuvenated. This illustrates in particular 5 in which this preferred embodiment is contrasted with a hypothetical channel formation, indicated by a dot-dash line, for which this distance A is constant. As indicated by the indication "constant" in the drawing, run in the hypothetical, although possible in the invention, but not preferred embodiment, the deck-side guide surface 8th and the bottom-side guide surface 9 equidistant to each other.

What the through 3 to 5 exemplary reproduced installation of a radial impeller according to the invention 10 in a fan unit according to the invention 20 relates, various technical measures, which relate to the nature of this installation, optionally make further advantageous contributions to achieve an increase in the efficiency η while maintaining a high power density L and a low total sound power level L _w .

In particular, it may be provided that an inlet 21 of the housing 7 for the radial impeller 10 designed nozzle-shaped, wherein the inlet 21 of the housing 7 especially in the intake 4 the cover disk 1 dips in, as most clearly 3 , but also 4 and 5 demonstrate.

This training is in contrast to a view of the art, according to which of a nozzle-shaped cover plate, as is customary in centrifugal fans with backward curved blades, no improvement in the efficiency η could be expected.

In the known centrifugal fans with forward curved blades, the nozzles do not submerge in the cover disk. The static pressure difference at a gap between the nozzle-shaped inlet and the cover plate is too low in known radial wheels with forward curved blades, to achieve that axially through the inlet - along the longitudinal axis XX - moving main flow by a pulse supply from the additionally by the gap flows laterally into the intake opening of the cover disk reaching gap flow to the cover disk. In addition, the blades are thereby flowed axially near the cover disk, whereby the flow already separates at the blade entry edges.

In the invention may instead by the immersion of the nozzle-shaped inlet formed 21 in the intake 4 the cover disk 1 over the immersion length L _E forming gap 22 However, these disadvantages are avoided. The immersion length L _{E of} the gap 22 can be a size in the range of 0.5% to 5.0%, preferably in the range of 1.0% to 3.0%, of the outer diameter D _{a, DS of} the cover plate 1 and a gap width S _{w of} the gap 22 a size in the range of 0.5% to 5.0%, preferably 1.0% to 3.0%, of the outer diameter D _{a, DS of} the cover plate 1 exhibit.

As extremely favorable for the formation of the flow behind the inlet 21 it has been found, if an inner radius R _{i, S} at the front edge 2a the blades 2 (please refer 2 ) near the cover disk 1 greater than or equal to the inner radius R _{i, DS of} the intake opening 4 the cover disk 1 (please refer 3 ).

Furthermore - like this 3 shows - preferably be provided that a ratio V _{B of} a width B of the housing 7 at its air inlet 7b in the air duct 7a to an impeller outlet width b _{2 of} the radial impeller 10 on the radially outer air outlet side 5b of the flow channel 5 has a value that is in the range 1.0 ≦ V _B ≦ 1.4. As a result, the conversion of the dynamic pressure into static pressure is promoted while avoiding losses of the total pressure Δp _t . By such a design of the housing 7 with a - according to the specified ratio V _B - low width jump, the secondary flow in the housing 7 positively influenced, contrary to contrary opinions in the professional world leads to a significant increase in the efficiency η. It is advantageous in particular when the impeller outlet width b ₂ on the radially outer air outlet side 5b of the flow channel 5 assumes a value which is at most 70% of the total width b _{ges of} the radial impeller 10 is.

Finally, from the point of view of high efficiency, it is also advantageous if the housing 7 a spiral around the radial impeller 10 winding air duct 7a - Not with a rectangular - but with oval, preferably elliptical, from the side of the radial impeller 10 has continuously increasing cross-section. In such an elliptical cross-section, the ratio of the major to the minor axis of the ellipse may preferably be in the range of 1.2 to 3.0, wherein the major axis is different -. B. preferably vertically or horizontally - may be oriented.

The invention is not limited to the illustrated and described embodiments, but also includes all the same in the context of the invention embodiments. So can the Professional provide appropriate complementary technical measures, without departing from the scope of the invention. For example, it can be provided in an advantageous manner that an outlet diameter D _{a, S of} the blades 2 on the cover disk 1 less than or equal to the outer diameter D _{a, DS of} the cover plate 1 is. It can also be provided that this outlet diameter is less than or equal to the outer diameter D _{a, BS of} the bottom plate 3 is.

For the deck-side guide surface 8th and / or the bottom-side guide surface 9 of the flow channel 5 had already been stated that they can be executed curvature continuous. The same applies preferably to the respective printed pages 2c and suction sides 2d the blades 2 to, with the above formulations "at least partially ..." or "at least partially concave curved" (or: "... convexly curved") is expressed that the respective curvature curves, especially at their ends, also straight Sections may include.

In this respect, the radial impeller 10 in the case 7 coaxial with an electric drive motor 6 arranged, can - as in 3 and 5 shown - an outer contour 6a of the drive motor 6 in a motor receiving opening 3a (best visible in 2 ) of the bottom disk 3 engage positively or alternatively from a full-surface bottom plate 3 be covered, with the bottom plate 3 , preferably together with the contour 6a in its engine intake opening 3a recorded engine 6 , has a dome-shaped configuration. When using an engine 6 in the impeller area can by such a dome-shaped design of the bottom plate 3 Detachment from the engine contour and the backflow in the subsequent area can be prevented. This is shown for example by the comparison of 3 and 5 With 4 the latter being the unwanted formation of vortices W in a dead water area between engine 6 and bottom disc 3 illustrated.

Also a double-flow version of the radial impeller according to the invention 10 is possible without departing from the scope of the invention.

Furthermore, the invention has hitherto not been limited to the feature combinations defined in the independent claims 1 and 15, but may also be defined by any other combination of certain features of all the individual features disclosed overall. This means that in principle virtually every individual feature of the independent claims can be omitted or replaced by at least one individual feature disclosed elsewhere in the application.

LIST OF REFERENCE NUMBERS

1

Cover disc of 10

2

Scoop of 10 between 1 and 3

2a

Leading edge of 2

2 B

Trailing edge of 2

2c

Print side of 2

2d

Suction side of 2

3

Bottom disc of 10

3a

Motor intake opening for 6 in 3

4

Intake opening of 1

5

Flow channel in 10 between 2 / 2 and between 8th / 9

5a

Air inlet side of 5

5b

Air outlet side of 5

6

Drive motor for 10

6a

Outer contour of 6

7

Housing of 20

7a

Air duct of 7

7b

Air intake opening of 7 in 7a

8th

deck-side guide surface of 5

9

bottom-side guide surface of 5

10

Radial impeller

20

Fan unit with 10

21

Enema of 7

22

Gap between 21 and 1

A

shortest distance between 1 and 3

B

Width of 7 at 7b

b ₂

Impeller outlet width of 1

b _DS

Width of 1

b _ges

Total width of 10

D _{a, BS}

Outside diameter of 3

D _{a, DS}

Outside diameter of 1

D _{a, S}

Exit diameter of 2 at 1

D _{i, DS}

Inside diameter of 4 in 1

d _S

Profile thickness of 2

LR

Running direction of 10

L _E

Immersion length of 21 in 1 , Length of 22

L _S

Profile footage of 2

R _{i, S}

Inner radius of 2 at 2a

_{Ri, DS}

Inner radius of 4 in 1

S

Flow direction in 5 from 5a to 5b

T ₁

Tangent on 8th at 4

T ₂

Tangent on 8th at 5a

W

Whirl between 3 and 6 ( 4 )

X X

Longitudinal axis of 10 . 20

α _DS

Angle between T ₁ and T ₂

α _DS1

Angle between T ₁ and XX

α _DS2

Angle between T ₂ and XX

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006031167 A1 [0007]

Claims (19)

Radial impeller ( 10 ) with axial air inlet and air outlet over the impeller circumference, preferably for use in a spiral-shaped housing ( 7 ), with a bottom disc ( 3 ), which has an outer diameter (D _{a, BS} ), and with a concentric with the bottom disc ( 3 ) axially spaced arranged cover plate ( 1 ), which for the axial air inlet a circular suction port ( 4 ) having an inner diameter (D _{i, DS} ), as well as having a plurality of between the bottom plate ( 3 ) and the cover disc ( 1 ), forward curved, profiled blades, ( 2 ) between each two adjacent blades ( 2 ) a flow channel ( 5 ) with a radially inner air inlet side ( 5a ) and a radially outer air outlet side ( 5b ) is formed, which - seen in the running direction (LR) of the radial impeller ( 10 ) - convexly curved, characterized in that the outer diameter (D _{a, BS} ) of the bottom disc ( 3 ) - based on the inner diameter (D _{i, DS} ) of the suction port ( 4 ) - At least 20% larger than the inner diameter (D _{i, DS} ) of the suction port ( 4 ) is that the cover disc ( 1 ) for the flow channel ( 5 ) a deck-side guide surface ( 8th ), with one in the direction of the inlet opening ( 4 ) opening angle (α _DS ), which between a tangent (T ₁ ) to the deck-side guide surface ( 8th ) at the entrance to the suction opening ( 4 ) of the cover disc ( 1 ) and a tangent (T ₂ ) to the deck-side guide surface ( 8th ) at the exit from the flow channel ( 5 ) at its radially outer air outlet side ( 5b ) is formed, at least 30 °. Radial impeller ( 10 ) according to claim 1, characterized in that the outer diameter (D _{a, BS} ) of the bottom disc ( 3 ) - based on the inner diameter (D _{i, DS} ) of the suction port ( 4 ) - at least 50%, but at most 90% larger than the inner diameter (D _{i, DS} ) of the cover plate ( 1 ). Radial impeller ( 10 ) according to claim 1 or 2, characterized in that in the profiled blades ( 2 ) a profile thickness ratio (V _P ) of maximum profile thickness (d _S ) to total profile length (L _S ) is at least 0.15, in particular at least 0.2 and particularly preferably at least 0.25, wherein the profile thickness ratio (V _P ) is at most 0, 5, and especially 0.4, more preferably 0.35. Radial impeller ( 10 ) according to one of claims 1 to 3, characterized in that an inner radius (R _{i, S} ) at the front edge ( 2a ) of the blades ( 2 ) near the cover disc ( 1 ) greater than or equal to the inner radius (R _{i, DS} ) of the intake opening ( 4 ) of the cover disc ( 1 ). Radial impeller ( 10 ) according to one of claims 1 to 4, characterized in that an outlet diameter (D _{a, S} ) of the blades ( 2 ) on the cover plate ( 1 ) smaller than or equal to the outer diameter (D _{a, DS} ) of the cover disc ( 1 ) and / or less than or equal to the outer diameter (D _{a, BS} ) of the bottom disc ( 3 ). Radial impeller ( 10 ) according to one of claims 1 to 5, characterized in that the number of blades ( 2 ) is at least 19 and at most 54, and preferably in the range of 22 to 46. Radial impeller ( 10 ) according to one of claims 1 to 6, characterized in that the cover disc ( 1 ), the blades ( 2 ) and the bottom disc ( 3 ) are designed as a two-part, in particular of two injection molded plastic parts, materially connected composite body. Radial impeller ( 10 ) according to one of claims 1 to 7, characterized in that the bottom disc ( 3 ) in the flow channel ( 5 ) a bottom-side guide surface ( 9 ) trains. Radial impeller ( 10 ) according to one of claims 1 to 8, characterized in that the cover-side guide surface ( 8th ) and / or the bottom-side guide surface ( 9 ) of the flow channel ( 5 ) have a continuous curvature. Radial impeller ( 10 ) according to one of claims 1 to 9, characterized in that in each case the leading edges ( 2a ) of the blades ( 2 ) at the radially inner air inlet side ( 5a ) and / or the trailing edges ( 2 B ) of the blades ( 2 ) on the radially outer air outlet side ( 5b ) are rounded. Radial impeller ( 10 ) according to one of claims 1 to 10, characterized in that the cross section of the flow channel ( 5 ) in the direction of the radially inner air inlet side ( 5a ) to the radially outer air outlet side ( 5b ), wherein in particular a shortest distance (A) between the bottom plate ( 3 ) and the cover disc ( 1 ) decreases in the flow direction (S). Radial impeller ( 10 ) according to one of claims 1 to 11, characterized in that an impeller outlet width (b ₂ ) on the radially outer air outlet side ( 5b ) of the flow channel ( 5 ) has a value which is at most 70% of a total width (b _ges ) of the radial impeller ( 10 ) is. Radial impeller ( 10 ) according to one of claims 1 to 12, characterized in that its total width (b _tot ) ranges from 25% to 70% based on the outer diameter (D _{a, BS} ) of the bottom disc ( 3 ) lies. Radial impeller ( 10 ) according to one of claims 1 to 13, characterized in that in the direction of the inlet opening ( 4 ) opening angles (α _DS ), which between a tangent (T ₁ ) to the deck-side guide surface ( 8th ) at the entrance to the suction opening ( 4 ) of the cover disc ( 1 ) and a tangent (T ₂ ) to the deck-side guide surface ( 8th ) at the exit from the flow channel ( 5 ) at its radially outer air outlet side ( 5b ) is formed, at most 90 °, preferably at most 75 ° Fan unit ( 20 ), in particular drum fans, with a radial impeller ( 10 ) according to one of claims 1 to 14, characterized in that the radial impeller ( 10 ) in a housing ( 7 ), in particular in a spiral-shaped housing ( 7 ) is arranged. Fan unit ( 20 ) according to claim 15, characterized in that an inlet ( 21 ) of the housing ( 7 ) for the radial impeller ( 10 ) is designed nozzle-shaped, wherein the inlet ( 21 ) of the housing ( 7 ) in particular into the intake opening ( 4 ) of the cover disc ( 1 immersed). Fan unit ( 20 ) according to claim 15 or 16, characterized in that a ratio (V _B ) of a width (B) of the housing ( 7 ) at its air inlet ( 7b ) in an air duct ( 7a ) to a impeller outlet width (b ₂ ) of the radial impeller ( 10 ) on the radially outer air outlet side ( 5b ) of the flow channel ( 5 ) has a value that is in the range 1.0 ≦ V _B ≦ 1.4. Fan unit ( 20 ) according to one of claims 15 to 17, characterized in that the radial impeller ( 10 ) in the housing ( 7 ) coaxial with an electric drive motor ( 6 ), wherein an outer contour ( 6a ) of the drive motor ( 6 ) in a motor receiving opening ( 3a ) of the bottom disc ( 3 ) engages positively or by a full-surface bottom plate ( 3 ), and wherein the bottom disk, ( 3 ) preferably together with the contour ( 6a ) in its motor receiving opening ( 3a ) recorded engine ( 6 ), has a dome-shaped configuration. Fan unit ( 20 ) according to one of claims 15 to 18, characterized in that the housing ( 7 ) spirally around the radial impeller ( 10 ) convoluted air duct ( 7a ) with oval, from the side of the radial impeller ( 1 ) ago steadily increasing cross section.

Images