EP1608875B1 - Radial fan wheel, fan unit, and radial fan arrangement - Google Patents

Abstract

The radial fan impeller comprises a cover plate (3) and bottom plate (1) interconnected by a vane ring which has guide vanes (2) inclined from the inside outwards against the direction of rotation. Outer edge sections (7) which protrude beyond the vane outlet diameter are formed on the cover plate and bottom plate and define an annular diffusion chamber with an outside diameter which exceeds the vane outlet diameter by up to 25 per cent, and the cross sectional profile of which is constructed rectangularly or trapezoidally, widening outwards. Independent claims are also included for the following: (a) a fan unit with the aforesaid radial fan impeller; (b) a radial fan arrangement including the aforesaid radial fan impeller; (c) a use for the fan unit which is in an air conditioning unit; and (d) a use for the radial fan impeller which is as a freewheeling impeller.

Description

FIELD OF THE INVENTION

The invention relates to a radial fan with backward inclined vanes, a fan unit and a radial fan assembly.

BACKGROUND OF THE INVENTION

Such radial fan wheels or radial impellers are e.g. used in air conditioning and ventilation technology.

Also, forwardly inclined impellers with 30-40 vanes running from inside to outside in the direction of travel are used in aeration technology with diameters of 160 to 400 mm in conjunction with flow-forming volute casings. Their static efficiency is about 30 to 35%. Such a wheel is out of the JP 06299993 known. A version as a centrifugal fan with converging outlet ring shows the US 1,447,915 in which the centrifugally accelerated air is additionally accelerated by the radially outwardly converging outlet nozzle.

For larger volume flows predominantly backward inclined wheels are used, in which the guide vanes are inclined outwards against the running direction. The common diameters range from 200 to 1500 mm, for special applications diameters over 2500 mm are known. The static efficiency of such wheels is in the range of 70 to 74%. They are used with and - free-running - without volute casing, eg in so-called air conditioning boxes. In this case, the axially sucked from the outside through the inlet opening air occurs radially between the blades to the outside. To reduce unwanted noise emissions that occur during the operation of fan wheels, are either sound-absorbing (sound-absorbing) measures required or constructive measures on the impeller itself, which influence the exiting air flow noise-reducing.

US-A-6039539 , according to which the preamble of claim 1 has been formed, shows an impeller in which the outer edges of the blades have an oblique edge inclined to the rotation axis and the peripheral end portions of the end plates are curved to increase the sound pressure in a frequency range of 50 to 300 Hz reduce.

When the air flow exits the impeller, the abrupt expansion of the flow cross-section produces effects which impair the efficiency of converting the kinetic energy contained in the flow medium into the desired static pressure increase. To improve this efficiency, fixed diffuser rings with a vane grille, as for example EP-A-1 039 142 are known, arranged following the fan. However, such diffuser rings are structurally complex, space consuming and expensive.

SUMMARY OF THE INVENTION

The invention provides a radial fan according to claim 1 according to a first aspect.

Another aspect relates to a fan unit with a suction plate with integrated inlet nozzle, which is connected via a holder by means of carriers with a drive, a supporting bracket. A fan according to claim 1 is arranged on a drive shaft between the drive and the inlet nozzle.

Another aspect relates to a radial fan assembly comprising: a radial fan as claimed in claim 1, and a zone radially adjacent to the diffusion space and end-to-end to at least one outer peripheral region and not including the pressure and / or velocity profile of a fluid flowing through said zone Having significant influencing vanes.

Other features are included in the disclosed apparatus and methods, or will become apparent to those skilled in the art from the following detailed description of embodiments and the attached drawings.

DESCRIPTION OF THE DRAWINGS

Fig. 1

eine dreidimensionale Ansicht ei- nes Lüfterrades zeigt,

Fig. 2

einen Axialschnitt des in Fig. 1 gezeigten Lüfterrades entlang der Drehachse darstellt,

Fig. 3

eine Ansicht des Lüfterrades in Richtung der Drehachse auf die Bo- denscheibe ist,

Fig. 4

eine Gestaltungsvariante des Rand- bereichs des Lüfterrades angibt,

Fig. 5

eine alternative Gestaltungsvari- ante des Randbereiches zeigt,

Fig. 6a und b

eine Anordnung eines freilaufenden Lüfterrads in einem Klimakasten im Axialschnitt und Querschnitt zei- gen, und

Fig. 7a und b

eine Anordnung eines (nicht frei- laufenden) Lüfterrads in einem Spiralgehäuse im Axialschnitt und Querschnitt zeigen.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

Fig. 1

shows a three-dimensional view of a fan wheel,

Fig. 2

an axial section of the in Fig. 1 represents shown impeller along the axis of rotation,

Fig. 3

is a view of the fan wheel in the direction of the axis of rotation on the bottom plate,

Fig. 4

indicates a design variant of the edge area of the fan wheel,

Fig. 5

shows an alternative design variant of the edge region,

Fig. 6a and b

an arrangement of a free-running fan in an air conditioning box in axial section and cross-section show, and

Fig. 7a and b

show an arrangement of a (non-free-running) impeller in a spiral housing in axial section and cross section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. 1 shows a three-dimensional view of a fan. Before a detailed description of the Fig. 1 First, various explanations of the embodiments follow.

In the fan wheels shown is between outer edge regions of the top and bottom disc, which protrude beyond the Schaufelaustrittsdurchmesser, an annular Diffusion space formed in which the exiting fluid flow is calmed and kinetic energy is converted low loss in static pressure. The cross-sectional profile of this "diffusion ring" can be constructively and manufacturing technology in a particularly simple manner rectangular by the outer diameter of the cover and bottom plates are increased accordingly to the blade outlet diameter. It may alternatively be widened outwardly in a trapezoidal shape, wherein the additional cross-sectional widening of the diffusion effect is enhanced and thus the efficiency can be increased, and the diameter of the wheel is reduced.

In some embodiments, the outer diameter (DN) of the diffusion space (eg, 16 in Fig. 2 . 4, 5 ) exceeds the blade exit diameter (DAs) by 8% to 20%, preferably 10 to 15% and more preferably by 12%. These are the diameter ranges in which the mentioned effect occurs the most.

In some of the embodiments, the outer edge region (eg, 7 in FIG 4 and 5 ) and a plane normal to the rotation axis an angle α, which is smaller than 35 °, and for example less than 25 °. For example, the angle α is 12 °. These are opening angles at which the desired air flow is particularly effective and a particularly effective diffusion effect is achieved.

In embodiments with a particularly effective design of the fan wheel in the region of the air inlet, the inlet opening of the cover disk is widened in a trumpet shape inwards. In some of these embodiments, the inner edges of the vanes have a convex curvature in the connection area to the cover disk.

In some embodiments, the bottom disc (eg, 1 in FIGS Figures 1-6 ) provided with a hub assembly (eg 9).

In some of the embodiments, the number of blades of the fan is in the range of six to ten blades.

For example, the blade entry angle is in the range of 19 ° to 25 °, for example, the blade exit angle is in the range of 28 ° to 34 ° (the indicated values are each included).

The embodiments also show fan units with a suction plate (eg 7) with integrated inlet nozzle (eg 18) which is connected via a holder (eg 19) by means of carriers (eg 20) to a holder (eg 22) carrying a drive (eg 22) wherein a fan according to one of the embodiments on a drive shaft (eg 23), between the drive and the inlet nozzle is arranged.

Some embodiments relate to radial fan assemblies in which the impeller is used largely free of additional flow-conducting elements and in particular the air outlet area of such elements is kept free. Such a radial fan arrangement has a radial fan and a zone radially to the diffusion space and has frontally adjacent to at least one outer edge region, and none of the pressure and / or velocity profile of a fluid flowing through this zone has substantially influencing vanes.

In some embodiments, said fan wheels are referred to as free-running fan wheels, e.g. used in essentially cube-shaped air conditioning boxes. In other embodiments, the use of the fan wheels in spiral housings

Now returning to Fig. 1 , the impeller shown is formed from a flat bottom disk 1, a blade ring consisting of a plurality of stator blades 2 and a cover disk 3. Bottom and cover plate 1, 3 are arranged concentrically with respect to the axis of rotation 4 at a distance B and are connected to each other via the blade ring. The cover plate 3 has an inlet opening 5 with the diameter DE, through which a flow medium is sucked during operation.

In this case, the cover plate 3 extends from a inlet opening 5 delimiting frontal edge 6, starting in a trumpet-shaped widened inwardly and radially into an outer edge region 7. The bottom plate 1 is formed as a circular disk and carries a centrally located hub assembly 9 with an opening 10 which is provided with a drive unit can be connected to drive the fan ( Fig. 6 ). In a non-illustrated embodiment, bottom plate and drive flange may also be integrally formed.

Bottom and cover plate are limited radially by their outer edges 8 and are connected to each other via the blade ring at a distance B (drive with external rotor motor).

In the exemplary embodiment shown, the blade ring has seven stator blades 2, which are arranged uniformly in a star shape relative to the axis of rotation 4. Here, the inner edges 11 facing the axis of rotation 4 define a diameter DSi and the outer edges 12 a blade outer diameter DSa. The actual vane blade extends from the inner edge 11, starting radially and inclined towards the running direction R to the outside, where it ends at the vane outer edge 12 ( Fig. 3 ). In addition, the axially extending vanes are curved with respect to the rotation axis 4 with the convex sides facing outward. Such a fan is also referred to as a backward curved impeller, it is provided in alternative (not shown) versions with eg 6 to 14 blades, while the vanes 2 can also be designed flat. Their side edges are suitably connected to the bottom or the cover plate 1, 3, wherein the contours of the side edges in their connection region in each case the curvature of the bottom 1 and the cover plate 3 follow. Outer and inner edge 12, 11, extend substantially parallel to the axis of rotation 4, wherein in the illustrated embodiment, the inner edge 11 is curved in the connection region to the cover plate for manufacturing and aerodynamic reasons.

As blade entry angle β ₁ ( Fig. 3 ) Here, the angle of the tangent at the inner root of the blade to the running through this base point circumferential perimeter is meant as a blade exit angle γ corresponding to the angle of the tangent to the outer root of the blade to the running through this base point circumference tangent. For blades of suitable logarithmic curvature, the entrance and exit angles are the same; in the embodiments shown in the figures, the blades are less curved, so that the blade entry angle β _{1 is} smaller than the blade exit angle β ₂ . Bottom and cover plate 1, 3 have an outer diameter DN, which is above the blade outer diameter DSa, so that between the outer edge 8 of the bottom plate 1 and the outer diameter Leitschaufel DSa an outer edge region 14 is defined. The distance between the cover and bottom plate 3, 1 or the blade width B is maximum: $$5\left(\mathrm{DN}-\mathrm{DSa}\right)/2$$

In operation, the fan is in the drive direction R ( Fig. 3 ), and the vanes promote the flow fluid inside the fan wheel to the outside, where it exits substantially radially at the impeller outer diameter DSa. Due to the negative pressure caused in the inside of the rotor fluid is sucked from the outside through the inlet opening 5. The flow direction thus extends coaxially through the inlet opening 5 in the interior of the impeller and is guided radially outwards, wherein the flow cross section is constantly expanding. The flow initially leaves the diameter of the blades DSa the interspaces 15 in a diffusion space 16, the annular between the outer edges 12 of the vanes 2, the outer edge regions 7, 14 of the cover or the bottom plate 3, 1, and the outer diameter DN of the corresponding outer edges 8 is defined. The design of this area affects the efficiency and noise of the fan. Characterized in that the radial flow is held axially on both sides by the outer edge regions 7, 14 after leaving the blade interspaces 15 before it leaves the fan, the so-called. Carnot diffuser effect is avoided, which would occur in the axial release of the flow immediately. As a result of the flow guidance according to the invention, controlled diffusion takes place in the diffusion space, ie, the kinetic energy supplied to the fluid in the blade interspaces 15 converted into a pressure potential with low losses. That is, fluidically expressed: The kinetic pressure is converted into static pressure. By avoiding the Carnot diffusion, the efficiency increases and the reduction of turbulence at the exit edges 8 and 12 lowers the noise emission.

The embodiments according to 4 and 5 define a diffusion space 16 whose cross-section, in contrast to in Fig. 2 shown rectangular shape is widened trapezoidal shape to the outside. To Fig. 4 the outer edge region 7 of the cover plate 3 is open to the outside by an angle α, which lies in a range between 0 and 35 °. This additional expansion enhances the diffusion effect and makes it possible to make the outer edge regions 7, 14 narrower so that the outer diameter DN, for example, must be only 20% or less above the blade outer diameter DSa, but should be at least 8% higher.

Fig. 5 shows a corresponding expansion of the two outer edge regions 7, 14 of the bottom and cover plate 1, 3. The edge widening can also be performed only on the bottom plate 1 (not shown).

Fig. 6 shows a complete unit in axial section ( Fig. 6a ) and cross section ( Fig. 6b ), which in addition to the above-described fan additionally having a suction plate 17 with integrated inlet nozzle 18 which is connected via brackets 19 and support 20 with a motor bracket 21, which in turn carries a motor 22, the drive shaft 23 is coupled to the hub assembly 9 of the fan , This complete unit with freewheeling fan wheel is inserted into a substantially cube-shaped air conditioning box 24. In this, a pressure is built up by the fan unit in the interior, which generates volume flows in one or more outgoing channels. As a rule, such air conditioning boxes are not fluid dynamic are designed, the specified diffusion effect is particularly effective here, as can be largely dispensed with additional flow-conducting or sound-insulating measures. In particular, vanes radially adjacent to the diffusion space 16 adjacent guide elements, such as fixed diffusion rings. In addition, the outwardly facing end side of one or both outer edge regions 7, 14 is also free of guide elements. The fan 1 is not surrounded in the air box 24 by a spiral housing; the walls of the air conditioning box are relatively far away in the radial direction from the outer edge of the fan wheel, ie the diffusion space (typically more than 15% of the fan wheel radius, ie half the outer diameter of the diffusion space (DN)), and the fan is at the outer diameter of the diffusion space ( DN) in one or both axial directions without a housing closing off the diffusion space (ie the walls of the air conditioning box are wider in the axial direction than the width of the wheel at the exit from the wheel).

With a fan wheel with the following dimensions, an efficiency increase of 5% points was achieved in a free-running arrangement: Outer diameter DN: 457 mm Blade outer diameter DSa: 406.4 mm Shovel inner diameter DSi: 252.4 mm Blade width at exit B: 110.5 mm Inlet opening diameter DE: 257.4 mm Bucket entry angle β ₁ : 22 ° Bucket exit angle β ₂ : 31 °.

The dimensions for further embodiments of fan wheels are in the following range: Outer diameter DN: 200 - 1800 mm Blade outer diameter DSa: 160 - 1400 mm Shovel inner diameter DSi: 100 - 650 mm Blade width at exit B: 40 - 280 mm Inlet opening diameter DE: 98 - 660 mm Bucket entry angle β ₁ : 19 ° - 25 ° Bucket exit angle β ₂ : 28 ° - 34 °.

As Fig. 7a (Axial section) and 7b (cross-section) show, the described impeller 1, however, can also be used in conjunction with a spiral housing 25, since the increase in efficiency can be used here as well. The spiral housing 25 has a tongue 26; this is formed by the part of the spiral housing in which the radial distance to the fan wheel is minimal (it is for example less than 15% of the fan wheel radius). Starting from the tongue 26, this distance increases (for example, linear or logarithmic) up to an outlet opening 27. In the axial direction, the volute can eg directly to the diffuser forming walls of the wheel connect, or be arranged for example at a distance x of these, the eg, as in Fig. 7a smaller than the width of the wheel at the outlet (ie at the diffuser).

Claims (10)

1. A radial fan wheel with a cover disc (3), having an entrance opening (5), and a base disc (1), which are connected to each other by way of a vane ring which has guide vanes (2) extending at an inclination towards the outside from the inside in a direction opposed to the running direction and orientated in the axial direction, wherein the cover disc (3) and the base disc (1) have formed thereon outer edge areas (7, 14) which project beyond the vane exit diameter (DSa) and which define an annular diffusion space (16) with an external diameter (DN) which exceeds the vane exit diameter (DSa) by up to 25 %, wherein the radial fan wheel has no vanes outside the vane exit diameter (DSa), characterized in that the guide vanes (2) have outer edges (12) which extend parallel to the axis (4) of rotation and which define the vane exit diameter (DSa), and the projecting outer edge areas (7, 14) extend in a straight line in cross-section and in this way the cross-sectional profile of the diffusion space (16) is made rectangular or widened outwards in a trapezoidal manner.
2. A radial fan wheel according to claim 1, in which the entrance angle (β₁) of the guide vanes (2) amounts to from 19° to 25° and the exit angle (β₂) thereof amounts to from 28° to 34°.
3. A radial fan wheel according to claim 1, in which the external diameter (DN) of the diffusion space (16) exceeds the vane exit diameter (DSa) by from 8° to 20°.
4. A radial fan wheel according to claim 1, in which the outer edge areas (7, 14) and a plane at a right angle to the axis of rotation form an angle α which is smaller than 35°.
5. A radial fan wheel according to claim 4, in which the angle α amounts to 12°.
6. A radial fan wheel according to claim 5, in which the entrance opening (5) of the cover disc is widened towards the inside in the shape of a trumpet.
7. A radial fan wheel according to claim 6, in which the inner edges (10) of the guide vanes (2) have a convex curvature in the area adjoining the cover disc (3).
8. A radial fan wheel according to claim 7, in which the base disc (1) is provided with a hub arrangement (9).
9. A fan unit with a suction plate (7) with an integrated intake nozzle (18) which is connected by means of supports (20) by way of a holding means (19) to a holding means (21) supporting a drive (22), wherein a fan wheel according to claim 1 is arranged on a drive shaft (23) between the drive (22) and the intake nozzle (18).
10. A radial fan arrangement which has the following: a radial fan wheel according to claim 1, and a zone which abuts radially against the diffusion space (16) and at the front against an outer edge area (7, 14), and has no guiding elements substantially influencing the pressure and/or speed profile of a fluid flowing through this zone.

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