Fan with spiral housing

Abstract

A fan having an impeller wheel with more particularly backwardly curved blades and having a spiral housing the flow channel of which is formed through an inner spiral contour of the housing, the flow channel guiding the air supplied from the impeller wheel through to an outlet, is characterised in that the local pitch angles of the spiral contour are adapted to the outflow angle out of the impeller wheel.

Description

[0001] The invention relates to a fan with an impeller, in particular with backward-curved blades, and with a spiral housing, the flow channel of which is formed by an inner spiral contour of the housing, wherein the flow channel directs the air conveyed by the impeller towards an outlet.

[0002] Spiral casing fans are particularly common for forward-curved radial and diagonal fans. Increasingly, spiral casings are also being used for backward-curved fans. Experience shows that using a spiral casing results in an additional pressure increase and a corresponding increase in static efficiency. Spiral casings are suitable for efficiently directing the outflowing air after the fan impeller into a flow channel running approximately perpendicular to the fan axis, for example, into a pipe with a round or square cross-section.

[0003] Backward-curved impellers typically result in only a slight increase in efficiency, as the outflow angles tend to be steeper (i.e., more radially oriented) than those of forward-curved impellers. Particularly in the area of ​​the flow channel with the smallest cross-sectional area, i.e., in the region of the blade, the outflowing air from backward-curved fans exhibits a steep angle of attack to the housing contour, which is generally detrimental to static efficiency and noise reduction.

[0004] For the purposes of prior art, reference is made only by way of example to DE 10 2005 012 815 A1. This document discloses a radial blower in a spiral housing, in which the housing's circumferential wall widens radially from the nozzle wall towards the bottom-disc wall. The housing is designed for a forward-curved impeller.

[0005] Any optimizations relating to a more or less steep lead-in of the inner contour are not known from this publication.

[0006] Publication WO 2017 / 106530 A1 discloses a fan which has the features of the preamble of claim 1.

[0007] The present invention is based on the objective of designing the generic fan with a spiral housing in such a way that it is particularly suitable for impellers with backward-curved blades. In particular, higher efficiencies and improved acoustics are to be achieved in radial or diagonal fans with backward-curved impellers.

[0008] Furthermore, the housing should be compact. Additionally, the housing should be simple in design and therefore inexpensive to manufacture.

[0009] The aforementioned problem is solved with respect to the fan by the features of claim 1. According to this claim, the spiral contour of the spiral casing with its local helix angles, i.e., in the course of the flow channel, is adapted to the outflow angle from the impeller, such that a mean helix angle of the spiral contour in the sector region with an azimuth angle of θ = 0° to θ = 45° is more than twice as high as in the sector region with an azimuth angle of θ = 45° to θ = 180°.

[0010] According to the invention, it has been recognized that the spiral contour with its local helix angles is of particular importance with regard to efficiency and noise generation. Thus, according to the invention, the spiral contour is adapted to the outflow angle from the impeller, and this is achieved in a compact design.

[0011] The development of the fan according to the invention, or rather the spiral casing used therein, relates to backward-curved radial or diagonal fans with an adapted inner contour. The local helix angle of the spiral contour, viewed approximately in the direction of rotation of the impeller, begins at a larger value from a narrowest point in the flow channel, preferably located near or at a tongue, and continues to a greater value further along the channel, up to an outlet with a contour farther from the tongue. The initially large helix angle then rapidly decreases again to lower values ​​along the circumferential direction of the flow channel, particularly to ensure the compactness of the spiral casing.

[0012] Typically, the local slope angle of the inner contour of the spiral casing, especially over a sector range of approximately 24° to 55°, starting from the narrowest area of ​​the flow channel or from the tongue, has significantly higher average values ​​than in the further course of the flow channel after the sector range.

[0013] There are several ways to define specific locations and areas within the flow channel in light of the features of the invention. For example, the beginning of the spiral contour near the tongue can be defined as the point on the inner contour of the housing that is closest to the impeller axis, or at which, moving from the tongue in the direction of rotation of the impeller, the curvature of the inner contour changes its sign. The radius of the circle of curvature is small at the beginning of the spiral contour, namely in the narrowest part of the flow channel, compared to the radius of curvature over a large portion of the spiral contour. Advantageously, the radius of curvature of the spiral contour is minimal at its beginning.

[0014] In a further advantageous manner, the radius of the circle of curvature at the beginning of the spiral contour is at least slightly smaller than the maximum radius of the impeller. That is, the radius of curvature at the starting point is smaller than in the prior art, where the spiral contour regularly exhibits a logarithmic spiral. This results in a particularly high efficiency and particularly low noise emission for the spiral housing according to the invention for backward-curved impellers.

[0015] A further advantageous feature is that there is a distance of at least 6% or 10% of the maximum radius of the impeller between the tongue and the largest radius of the impeller or the impeller blades, which is particularly advantageous for low noise levels.

[0016] For a simple housing design, it is advantageous if the housing essentially consists of two halves. One half, on the inlet nozzle side, includes the inlet nozzle and, optionally, an upstream inlet area with a larger outer radius than the inlet nozzle. The other half, on the motor side, includes mounting points for the motor and stator. Both housing halves can be manufactured using injection-molded plastic.

[0017] In light of the foregoing, it becomes clear that the two housing halves not only form the housing itself, but also include functional components, such as the integrated inlet nozzle through which ambient air flows into the impeller during fan operation. The same applies to the upstream inlet surface, which has a larger outer radius than the inlet nozzle. Advantageously, the inlet surface is designed radially outside the inlet nozzle as a flat or planar surface, the outer radius of which can be, for example, 35% larger than the largest radius (outer radius) of the inlet nozzle.

[0018] Fastening means for the motor and stator are provided on the motor-side housing half, and these may also be integrated there.

[0019] The two housing halves are advantageously connected at a flange-like joint, the flange being equipped with holes for screw connection. It is also conceivable to connect the two housing halves by clipping, riveting, or gluing.

[0020] In the area around the outlet from the spiral casing, through which the air conveyed through the flow channel exits, a mounting flange can preferably be formed directly on the casing halves. This flange allows the entire fan to be attached to a surrounding structure, such as an air handling unit, an air duct, etc. Holes can also be provided there to allow for fastening by screws.

[0021] Since significant overpressures compared to the surrounding environment can occur inside the fan during operation, particularly within the flow channel, it is advantageous to equip the two housing halves with stiffening elements, such as stiffening ribs. This achieves greater dimensional stability, enabling it to withstand the high pressures and, in particular, any pressure fluctuations.

[0022] As an alternative to the housing design discussed above, it is conceivable that the spiral housing comprises a substantially flat or planar motor-side side panel, a substantially flat or planar inlet nozzle-side side panel, and a preferably developable circumferential section, wherein the parts are advantageously made of sheet metal. Accordingly, the side panels are side sheets. The circumferential section can be designed as a developable spiral sheet, which forms the inner contour of the flow channel.

[0023] The motor-side side panel can include an inspection opening with a closable cover, facilitating access to the motor and impeller. An inlet nozzle can be integrated into the nozzle-side side panel, either as a single piece or as a separate sheet metal or plastic component. The side panels can form, for example, a rectangular or square air outlet. For additional reinforcement, a further reinforcing sheet metal component, functioning as a mounting flange, can be provided and attached to the outlet side of the side panels. As in the previously discussed embodiment, the mounting flange serves to attach the fan to a higher-level system, such as an air handling unit or an external air duct.

[0024] There are now various ways to advantageously develop and further refine the teaching of the present invention. For this purpose, reference should be made, on the one hand, to the claims subordinate to claim 1 and, on the other hand, to the following explanation of preferred embodiments of a fan according to the invention with reference to the drawing. In conjunction with the explanation of the preferred embodiments of the invention with reference to the drawing, generally preferred embodiments and further developments of the teaching are also explained. The drawing shows Fig. 1 shows a fan with a spiral casing in a view along the impeller axis and in a section on a plane transverse to the impeller axis. Fig. 2 shows a perspective view of the inlet nozzle and the outlet of the fan with a spiral casing. Fig. 1 , Fig. 3 in a schematic representation with a viewing direction corresponding to the from Fig. 1the course of the inner contour of the spiral casing Fig. 1 and Fig. 2 Viewed in a section perpendicular to the wheel axis, Fig. 4, the representation according to Fig. 3 , wherein the largest inner circle coaxial to the impeller and the circle of curvature at the tongue-adjacent beginning of the spiral contour are also shown, Fig. 5 the representation according to Fig. 3 , in addition schematically showing a section through the impeller and the circle of curvature at the tongue-adjacent beginning of the spiral contour, Fig. 6 the representation according to Fig. 3 , wherein the azimuth angle θ of a point on the inner contour and the determination of the associated local inclination angle α of the inner contour are additionally shown, Fig. 7 in perspective view a fan with a further embodiment of a spiral housing, which is essentially made of sheet metal, Fig. 8 in a view in the direction of the impeller axis and in a section on a plane transverse to the impeller axis the fan with spiral housing according to Fig. 7 , Fig. 9 in a schematic representation with a viewing direction corresponding to that from Fig. 8 the course of the spiral contour of the spiral casing Fig. 7 and Fig. 8 as seen in a section perpendicular to the wheel axis, Fig. 10 the representation according to Fig. 9 , wherein in addition the largest inner circle coaxial to the impeller and the azimuthal position of the beginning of the spiral contour at the tongue are shown, Fig. 11 shows in a diagram two typical profiles of the distance of the spiral contour from the impeller axis of spiral casings, Fig. 12 shows in a diagram two typical profiles of the helix angle α of the spiral contour of spiral casings, Fig. 13 shows in a diagram two typical profiles of the curvature κ of the spiral contour of spiral casings.

[0025] In Fig. 1A fan 1 with a spiral casing 2 is shown in a view along the impeller axis and in a section on a plane perpendicular to the impeller axis. In this exemplary embodiment, the spiral casing 2 is made up of two halves (see also...). Fig. 2 ), where the section shown here runs exactly through the, in this case, planar dividing surface of the two halves. The planar section, perpendicular to the fan axis, is located at the position, viewed in the direction of the axis, where the area enclosed by the inner contour 4 of the spiral housing 2 and the outlet 5 is approximately at its maximum.

[0026] In addition to the spiral housing 2, the fan consists in particular of a motor 10 with rotor 11 and stator 12, which are shown schematically in section. Furthermore, the fan comprises an impeller 3 consisting of a base plate 7, a cover plate (not shown due to the section), and blades 8 extending between them. The impeller 3, which is advantageously manufactured by injection molding of plastic, is, in the exemplary embodiment, attached to the rotor 11 of the drive motor 10 at its base plate 7 by means of a sheet metal disc 13. In operation, the impeller 3 rotates clockwise, as seen in this view. Accordingly, this is a backward-curved impeller 3, i.e., an impeller 3 with backward-curved vanes 8. In backward-curved impellers 3, the thrust side 44 of a vane 8, which leads the suction side 43 of the same vane 8 in the direction of rotation of the impeller 3 during operation, is convex, while the suction side 43 of the vane 8 is concave.The wings 8 are curved in the opposite direction to the rotation, especially when considering the course of the wings 8 from radially inside (from the leading edge) to radially outside (towards the trailing edge).

[0027] During fan operation, the conveyed air exits radially outwards from the impeller 3 into the flow channel 45 of the spiral housing 2, which extends essentially circumferentially with respect to the impeller axis. From a narrowest point in the region of the tongue 9, the flow channel 45 widens circumferentially to accommodate the increasing airflow, towards an outlet 5 from the spiral housing 2. The design and course of the inner contour 4, which significantly influences the efficiency and acoustics of the fan, are essential to the invention. This course and its key features are shown in the illustrated embodiment. Figs. 5 to 8 further described.

[0028] Fig. 2Figure 1 shows in a perspective view the inlet nozzle 14 and the outlet 5 of the fan 1 with spiral casing 2 according to Fig. 1 The structure of the spiral housing 2 of this embodiment, comprising essentially two halves 2a and 2b, is clearly visible. These halves 2a and 2b are advantageously manufactured using plastic injection molding. The inlet nozzle 14 is integrated into the nozzle-side half 2a, through which ambient air flows into the impeller 3 during fan operation. In the illustration, parts of the impeller 3 (blade 8 and base plate 7) as well as the rotor 11 of the motor 10, on which the impeller 3 is mounted, are visible through the inlet nozzle 14. Advantageously, a flat or planar inlet surface 24 is formed radially outside the inlet nozzle 14 on the upstream side, the outer radius of which is at least 35% larger than the largest radius of the inlet nozzle 14 with respect to the fan axis.

[0029] The motor 10, with its stator 12, is attached to the motor-side half 2b by corresponding mounting devices integrated into the motor-side half 2b. The two halves 2a and 2b are connected to each other at a connection area 16. In the exemplary embodiment, a type of flange with bores 17b is shown, to which the halves 2a and 2b can be connected by screws. Other connection methods are also conceivable, for example, advantageously by clipping, riveting, and / or gluing.

[0030] In the area around the outlet 5 from the spiral housing 2, through which the air exits and advantageously flows into a suitably shaped channel, a mounting flange 15 is provided. The entire fan 1 is attached to this flange on a surrounding structure, for example, an air handling unit or an air duct. In the exemplary embodiment, the bores 17a serve this purpose, allowing screws to be attached. Since considerable overpressures compared to the external environment can occur inside the spiral housing 2, in its flow channel 45, during operation, the two halves 2a and 2b are provided with stiffening elements 18, in this case stiffening ribs 18, for improved dimensional stability.

[0031] In Fig. 3 is in a schematic representation with a viewing direction corresponding to that from Fig. 1 the course of the inner contour 4 of the spiral casing 2 from Fig. 1 and Fig. 2The diagram shows a section viewed transversely to the impeller axis. A representative section perpendicular to the impeller axis 25 should be considered, for example, at the point, viewed along the axis, where the area enclosed by the inner contour 4 and the outlet 5 is at its maximum, or at the level of the center of the impeller outlet, or approximately in the center of the flow channel 45. In the schematic representation shown, the inner contour 4, which encloses an outlet 5 where the inner contour 4 is open, is particularly visible. It can be subdivided into a tongue-side outlet contour 27, a tongue 9, a spiral contour 26 extending approximately around the impeller axis 25, and a tongue-remote outlet contour 28.

[0032] Fig. 4 shows the representation according to Fig. 3, wherein, in addition, the largest inner circle 29 coaxial with the impeller and the circle of curvature 32 of the spiral contour 26 at the tongue-adjacent start 30 are shown. The tongue-adjacent start 30 of the spiral contour 26 can be defined as the point of the inner contour that has the smallest distance to the impeller axis 25, or as the point at which, moving from the tongue 9 in the direction of rotation of the impeller 3, the curvature of the inner contour 4 changes its sign. The radius of the circle of curvature 32 at the start of the spiral contour 26 is advantageously small compared to the course of the circle of curvature radius over a large part of the course of the spiral contour 26; advantageously, the radius of the circle of curvature of the spiral contour 26 at the start point 30 is minimal.

[0033] Fig. 5 shows similar to Fig. 4 the representation according to Fig. 3The figure also schematically shows a section through the impeller 3 and the circle of curvature 32 of the spiral contour 26 at the tongue-proximal start 30. In this embodiment, the radius of curvature 32 at the start of the spiral contour 26 is smaller than the maximum radius 33 of the impeller 3; that is, this radius of curvature 32 at the starting point 30 is smaller than in the prior art with a spiral contour, for example, a logarithmic spiral. This results in a particularly high efficiency and particularly low noise emission for the spiral housing 2 for backward-curved impellers. There is a distance of at least 6% or 10% of the maximum radius 33 of the impeller 3 between the tongue 9 and the largest radius 33 of the impeller 3 or the vanes 8 of the impeller 3, which is particularly advantageous for low noise generation.

[0034] Fig. 6 shows, similar to Fig. 4 and Fig. 5 , the representation according to Fig. 3The figure shows the azimuth angle θ(36) of a point P(35) on the spiral contour 26 and the determination of the corresponding local inclination angle α(37) of the spiral contour 26. The position of a point P(35) on a spiral contour 26 is determined by the azimuth angle θ(36). This is the angle between the line segment from the impeller axis 25 to point P(35) and the reference ray 31, which connects the impeller axis 25 with the starting point 30 of the spiral contour 26. At each point P(35), the angle α(37) between the circumferential direction (the tangent to a circle 34 coaxial with the impeller through P(35)) and the spiral contour 26, or its local tangent at P(35), can be defined. The shape of this angle α (37) is crucial for achieving high efficiency and low noise levels. In particular, it should be considered within a range for θ (36) from 0° to 180°, with the shape near tongue 9 being especially important.In addition to the course of α (37) in the range for θ (36) from 0° to 180°, the course of the distance r of the spiral contour 26 from the impeller axis 25 can also be considered in this range, or the course of the curvature κ, where κ is the reciprocal of the local radius of curvature at a point P (35) for a specific θ (36). The spiral contour 26 can be characterized using these courses, and the... Figs. 11 to 13 show typical profiles for spiral housings according to the invention.

[0035] Fig. 11Figure 1 shows two typical curves of the distance r of a spiral contour 26 from the impeller axis 25 of spiral housings according to the invention. For both curves shown, the distance r has its smallest value at the starting point 30 of the spiral contour 26 at the tongue 9 and increases essentially monotonically along the spiral contour 26, at least up to θ=180°. Crucially, it increases relatively sharply in the sector range from θ=0° to θ=45°. For example, along the contour represented by the curve with the triangle symbols, it increases by 61 mm from 163 mm to 224 mm from θ=0° to θ=45°, which corresponds to an average rate of increase of 1.36 mm / 1° in this area, while from θ=45° to θ=180° it increases by 54 mm from 224 mm to 278 mm, which corresponds to an average rate of increase of 0.4 mm / 1° in this area.This means that the average rate of increase of the radius with respect to the azimuth angle θ is more than three times higher in the sector range from θ=0° to θ=45° than in the range from θ=45° to θ=180°.

[0036] In the second example, the radius of the contour represented by the curve with the square symbols increases by 19 mm from 103 mm to 122 mm between θ=0° and θ=45°, which corresponds to an average rate of increase of 0.42 mm / ° in this range. In contrast, from θ=45° to θ=180°, it increases by 20 mm from 122 mm to 152 mm, corresponding to an average rate of increase of 0.22 mm / ° in this range. This means that the average rate of increase of the radius with respect to the azimuth angle θ is more than 1.5 times higher in the sector range from θ=0° to θ=45° than in the range from θ=45° to θ=180°.

[0037] Fig. 12Figure 1 shows two typical profiles of the helix angle α of the spiral contour 26 of spiral casings according to the invention. Both profiles exhibit relatively high helix angles α in a sector range from θ=0° to θ=45°. For example, the helix angle α of the spiral contour represented by the curve with the triangle symbols has an average value of approximately 21° in the interval from θ=0° to θ=45°, while it has an average value of approximately 5.5° in the interval from θ=45° to θ=180°. That is, the average helix angle α of the spiral contour 26 is more than three times higher in the sector range from θ=0° to θ=45° than in the range from θ=45° to θ=180°.

[0038] In the second example, the slope angle α of the spiral contour, represented by the curve with the square symbols, has an average value of approximately 12° in the interval from θ=0° to θ=45°, while it has an average value of approximately 5.5° in the interval from θ=45° to θ=180°. This means that the average slope angle α of the spiral contour 26 is more than twice as high in the sector range from θ=0° to θ=45° as in the range from θ=45° to θ=180°.

[0039] Fig. 13Figure 1 shows two typical curves of the curvature κ of a spiral contour 26 of spiral casings according to the invention. Both curves exhibit relatively high curvatures κ in a sector range from θ=0° to θ=45°. For example, the curvature κ of the contour represented by the curve with the triangle symbols has an average value of approximately 0.0062 1 / mm in the interval from θ=0° to θ=45°, while it has an average value of approximately 0.0042 1 / mm in the interval from θ=45° to θ=180°. That is, the average curvature κ of the spiral contour 26 is more than 35% higher in the sector range from θ=0° to θ=45° compared to the range from θ=45° to θ=180°.

[0040] In the second example, the curvature κ of the contour represented by the curve with the square symbols has a mean value of approximately 0.01 1 / mm in the interval from θ=0° to θ=45°, while it has a mean value of approximately 0.0074 1 / mm in the interval from θ=45° to θ=180°. This means that the mean curvature κ of the spiral contour 26 is more than 30% higher in the sector range from θ=0° to θ=45° compared to the range from θ=45° to θ=180°.

[0041] It should also be noted that the preceding descriptions of the Figures 11 to 13 For example, a sector range of θ=0° to θ=45° was always chosen. Likewise, in other embodiments, a different sector range can be chosen, between the sector ranges of θ=0° to θ=24° and θ=0° to θ=55°.

[0042] In Fig. 7A perspective view shows a fan 1 with a further embodiment of a spiral housing 2, which is essentially made of sheet metal. The main components of the spiral housing 2 in the exemplary embodiment are a substantially flat motor-side side plate 39, a substantially flat nozzle-side side plate 40, and a substantially developable circumferential side plate 41, also referred to as a spiral plate 41, which, in a section on a plane perpendicular to the impeller axis, essentially defines the inner contour 4 (see Fig. 9The assembly features a motor-side side plate 39. In the exemplary embodiment, a maintenance cover 38 is attached to facilitate access to the motor and / or impeller. An inlet nozzle (not shown) is integrated into the nozzle-side side plate 40, either as a single piece or attached as a separate sheet metal or plastic part. The rectangular air outlet 5 in the exemplary embodiment is formed by the side plates 39 to 41. For additional reinforcement, a further sheet metal part is attached in the function of a mounting flange 15, in which holes 17a are provided to simplify the attachment of the spiral housing 2 or the fan 1 to a higher-level system such as an air handling unit or a flow duct.

[0043] In Fig. 8 In a view in the direction of the impeller axis and in a section on a plane transverse to the impeller axis, a fan 1 with the spiral housing 2 is shown according to Fig. 7The cross-section shows the circumferential side plate 41, which has the inner contour 4 on its inner side at the edge of the flow channel 45. The impeller 3, which is installed inside, is a backward-curved impeller with blades 8, a base plate 7, and a cover plate (not shown), whose direction of rotation during operation is clockwise in the illustration. It is driven by a motor 10, whose rotor 11, to which the impeller 3 is attached, is visible inside the impeller 3. The outlet 5 is surrounded by a mounting flange 15, which is designed as a separate sheet metal part. In this embodiment, a special feature is visible that is related to the special design of the inner contour 4. The entire inner contour 4, which has a special profile with large curves near the tongue 9, is not shown by the circumferential side plate 41.Part of the inner contour 4 is formed by an additional inner tongue plate 42, which may, for example, be made of thinner sheet metal. Furthermore, the inner tongue plate 42, in conjunction with the side plates 39 to 41, can provide additional stability to the spiral housing 2.

[0044] In Fig. 9 is in a schematic representation with a viewing direction corresponding to that from Fig. 8 the course of the inner contour 4 of the spiral casing 2 from Fig. 7 and Fig. 8The diagram shows a section viewed transversely to the impeller axis. A representative section perpendicular to the impeller axis 25 should be considered, for example, at the point, viewed along the axis, where the area enclosed by the inner contour 4 and the outlet 5 is at its maximum, or at the level of the center of the impeller outlet, or approximately in the center of the flow channel 45. In the schematic representation shown, the inner contour 4, which encloses an outlet 5 where the inner contour 4 is open, is particularly visible. It can be subdivided into a tongue-side outlet contour 27, a tongue 9, a spiral contour 26 extending approximately around the impeller axis 25, a tongue-removed outlet contour 28, and a distinct transition contour 46 between tongue 9 and outlet contour 27. For further details, please refer to the explanations regarding... Figs. 3 to 6 references which also apply here in essence.

[0045] In Fig. 10 is the representation according to Fig. 9shown, with the largest inner circle 29 coaxial to the impeller and the azimuthal position of the beginning 30 of the spiral contour 26 at the tongue 9 also being shown. Reference should also be made here to the explanations regarding Figs. 3 to 6 references which are also applicable here in essence.

[0046] Regarding further advantageous embodiments of the teaching according to the invention, reference is made to the general part of the description and to the attached claims in order to avoid repetition.

[0047] Finally, it should be expressly noted that the exemplary embodiments of the invention described above serve only to illustrate the claimed teaching and do not limit it to these exemplary embodiments. The scope of protection of the invention is defined by the following claims. Reference symbol list

[0048] 1 Fan 2 Spiral housing, housing 2a Nozzle-side half of the spiral housing / housing 2b Motor-side half of the spiral housing / housing 3 Impeller 4 Inner contour / spiral contour 5 Outlet 6 Transition area 7 Bottom disc of the impeller 8 Blade of the impeller 9 Tongue 10 Motor 11 Rotor of the motor 12 Stator of the motor 13 Sheet metal end 14 Inlet nozzle 15 Mounting flange 16 Connection area 17a Bores 17b Bores 18 Stiffening element, stiffening rib 19 Rotor of a motor 20 Stator of a motor 21 Not assigned 22 Not assigned 23 Connection area between partial housings 24 Inlet area 25 Impeller axis 26 Spiral contour, contour 27 Tongue-side outlet contour 28 Tongue-off Outlet contour 29 largest inner circle coaxial to the impeller 30 starting point of the spiral contour 310° beam, reference beam for azimuth angle determination 32 smallest circle of curvature of the spiral contour,Curvature circle at the start of the spiral contour 33 Maximum radius of the impeller 34 Circle coaxial to the impeller and through a point P of the inner contour 35 Point P on the inner contour 36 Azimuth angle θ of the inner contour 37 Pitch angle α of the inner contour at a point P 38 Maintenance cover, inspection opening 39 Motor-side side plate 40 Nozzle-side side plate 41 Circumferential side plate, spiral plate 42 Inner tongue plate 43 Blade suction side 44 Blade pressure side 45 Flow channel in the spiral housing 46 Transition contour,

Claims

1. Fan (1) having an impeller (3) having vanes (8) which are curved backwards and having a helical housing (2) whose flow channel (45) is formed by an inner contour (4) of the housing (2) containing a helical contour (26), wherein the flow channel (45) guides the air conveyed by the impeller (3) towards an outlet (5), characterized in that a mean pitch angle (37) of the helical contour (26) in the sector range with an azimuth angle (36) of from θ=0° to θ=45° is more than twice as high as in the sector range with an azimuth angle (36) of from θ=45° to θ=180° so that the helical contour (26) is adapted with the local pitch angles (37) thereof to the outflow angle from the impeller (3), wherein the azimuth angle θ is the angle between a path from an impeller axis (25) to a point P (35) on a helical contour (26) and a reference beam (31) which connects the impeller axis (25) to a starting point (30) of the helical contour, and wherein at each point P (35) the pitch angle α (37) is defined between a circumferential direction, that is to say, a tangent on a circle (34) coaxial to an impeller through P (35), and the helical contour (26) and / or the local tangent thereof at P (35).

2. Fan (1) according to claim 1, characterized in that the local pitch angle (37) of the helical contour (26) begins from a narrowest region in the flow channel (45) close to or on a tongue (9) substantially in the direction of rotation of the impeller (3) with a greater value than in the subsequent path as far as an outlet (5) with an outlet contour (28) remote from the tongue.

3. Fan (1) according to claim 1 or 2, characterized in that the local pitch angle (37) over a sector range with an azimuth angle (36) of from θ=24° to θ=55°, beginning at the narrowest region or at the tongue (9), has on average significantly higher values than in the subsequent path.

4. Fan (1) according to either claim 2 or 3, characterised in that the beginning of the helical contour (26) close to the tongue is defined as the point (35) of the inner contour (4) of the housing (2) which has the smallest spacing with respect to the impeller axis (25) or at which, moving from the tongue (9) in the rotation direction of the impeller (3), the curvature of the inner contour (4) changes its prefix.

5. Fan (1) according to any one of claims 2 to 4, characterised in that the radius of the circle of curvature (32) at the beginning of the helical contour (26), that is to say, in the narrowest region of the flow channel (45) or on the tongue (9), is small in comparison with the path of the radius of the circle of curvature over a large portion of the path of the helical contour (26), wherein the radius of the circle of curvature (32) of the helical contour (26) at the beginning of the helical contour (26) is advantageously minimal.

6. Fan (1) according to any one of claims 1 to 5, characterised in that the radius of the circle of curvature (32) at the beginning of the helical contour (26) is smaller than the maximum radius (33) of the impeller (3).

7. Fan (1) according to any one of claims 2 to 6, characterised in that between the tongue (9) and the largest radius of the impeller (3) or the vanes (8) of the impeller (3) there is a spacing of at least 6% or 10% of the maximum radius (33) of the impeller (3).

8. Fan (1) according to any one of claims 1 to 7, characterised in that the helical housing (2) substantially comprises two housing halves (2a, 2b), wherein an inflow-nozzle-side housing half (2a, 2b) comprises the inflow nozzle (14) and where applicable an inflow face (24) which is arranged upstream of the inflow nozzle (14) with a larger outer radius than the inflow nozzle (14), and wherein a motor-side housing half (2b) comprises securing means for the motor (10) with respect to a stator (12).

9. Fan (1) according to claim 8, characterised in that the two housing halves (2a, 2b) have a preferably flange-like connection region (23) as an outer edge region on or in which the housing halves (2a, 2b) are connected to each other by means of screws, clips, rivets or using adhesive technology.

10. Fan (1) according to any one of claims 1 to 7, characterised in that the helical housing (2) has a substantially planar motor-side side portion, a substantially planar inflow-nozzle-side side portion and a circumferential portion which can preferably be developed.

11. Fan (1) according to any one of claims 8 to 10, characterised in that the motor-side housing half (2b) or the motor-side side portion has an inspection opening (38) with a cover.

12. Fan (1) according to any one of claims 8 to 11, characterised in that the housing halves (2a, 2b) or the housing portions are produced with plastics injection-moulding or from sheet metal.

13. Fan (1) according to any one of claims 1 to 12, characterised in that the helical housing (2) has in the region of the outlet (5) a securing flange (15) which serves to secure the fan to any structure, wherein the securing flange (15) is a component of a housing half (2a, 2b) or a separate housing portion.

14. Fan (1) according to any one of claims 1 to 13, characterised in that a spacing r of the helical contour (26) from an impeller axis (25) has the smallest value at a starting point (30) of the helical contour (26) on a tongue (9), and increase over the course of the helical contour (26) up to an azimuth angle θ=180° in a substantially monotonous manner.

Images