Fan wheel having a undulated limiting surface, and fan comprising such a fan wheel

Abstract

The invention relates to a fan wheel (1) for rotation about an axis of rotation (X), comprising a base disk (10) with a first surface (11) facing an underside (B) in the axial direction and a second opposite surface (12) facing an upper side (A), and comprising a plurality of blades (20) which extend from the second surface (12) of the base disk (10) in the axial direction to the upper side (A) and together span a third surface (23) towards the upper side (A), wherein the first surface (11) and / or the second surface (12) and / or the third surface (23) are each a corrugated boundary surface of the fan wheel, which has at least one local maximum (31) and / or local minimum (32) in the axial direction along at least one contour (30) in the circumferential direction (U) around the axis of rotation (X).such that at least one boundary surface along at least one course (30) is curved multiple times in the axial direction and has a predetermined waviness.

Description

[0001] The invention relates to a fan wheel that can be rotated about a rotation axis for a blower or for a fan.

[0002] Fan wheels and fans are known in a variety of variants from the state of the art.

[0003] Regardless of the specific application, but especially for fans for ventilators, a smooth but also quiet running of the fan impellers is desirable and advantageous.

[0004] In general, impellers or fans driven in a rotary motion (i.e., around a rotational axis) generate first-, second-, and higher-order noise emissions. Higher-order noise can be effectively reduced by insulation, such as foam, or other soundproofing measures. However, first- or second-order noise, such as noise at the rotational frequency or a multiple of it, cannot be influenced, or can only be influenced to a limited extent, by such measures.

[0005] Tests and experience with known ventilation fans have shown that the sound, or rather the first- and second-order sound emissions, depend particularly on the axial and radial runout of the fan impeller, thus representing a significant influence on these sound emissions. The more precise the axial and radial runout, i.e., the smaller the height difference over a rotation, or the higher the axial and radial runout quality, the lower the resulting sound emissions.

[0006] However, with the currently known and cost-effectively implementable manufacturing processes, the limits of precision for improving the axial and concentricity quality have been reached, so that the fan wheels or the necessary mounts and bearings in the fans cannot be reasonably manufactured with even higher precision.

[0007] In order to further reduce noise emissions, especially first and second order noise, the state of the art therefore sometimes provides for reducing the speed of the fan wheels, which requires blowers with two, three or more compressor stages, each with a fan wheel, but this increases the necessary installation space, the manufacturing effort and also the manufacturing costs.

[0008] The invention is therefore based on the object of overcoming the aforementioned disadvantages and of providing a fan wheel and a fan having such a fan wheel, in which the rotation of the fan wheel generates the lowest possible noise emissions, in particular of the first and second order.

[0009] This problem is solved by the combination of features according to patent claim 1.

[0010] As described above, it is generally known that axial runout has a significant influence on the generated first- and second-order noise emissions. The axial runout (measured height difference over one revolution) measured when measuring axial runout on a fan impeller can be influenced in particular by the orientation of the surface on which the axial runout is measured relative to the rotation axis, as well as by the shape or waviness of the surface.

[0011] If the surface on which the axial runout is measured is tilted or not exactly orthogonal to the axis of rotation (angular error to the axis of rotation) or if the surface is not exactly flat but misshapen or wavy, the axial runout deteriorates and the noise emissions generated increase.

[0012] However, a large number of tests have surprisingly shown that, with the same measured values ​​for axial runout, a surface that is not exactly flat produces significantly lower noise emissions than a surface that is tilted relative to the axis of rotation.

[0013] According to the invention, a fan wheel for rotation about an axis of rotation is proposed, wherein the fan wheel is specifically designed for use in a fan, and more specifically, in a blower. Where circumferential direction, radial direction, or axial direction are subsequently mentioned, these refer to the axis of rotation, such that the circumferential direction is around the axis of rotation, the axial direction is along or parallel to the axis of rotation, and the radial direction is radiating from the axis of rotation. The proposed fan wheel has a base disk and a plurality of blades, which preferably extend in a spiral, i.e., curved, manner from the radial inside to the radial outside of the base disk.Along the axis of rotation, the fan wheel has a top side and an opposite bottom side, wherein the base plate defines, i.e. has or spans, a first surface towards the bottom side in the axial direction and a second surface towards the top side. The blades extend from the second surface of the base plate in the axial direction towards the top side and, on their side facing the top side and in particular with their respective end faces, jointly span a third surface. According to the invention, it is provided that the first surface and / or the second surface and / or the third surface is / are each a corrugated boundary surface of the fan wheel, so that the fan wheel accordingly has at least one corrugated boundary surface and preferably three corrugated boundary surfaces.The at least one boundary surface has at least one local maximum and / or local minimum, ie at least one local extreme point in the axial direction, along at least one particularly circular course in the circumferential direction around the axis of rotation, which course is preferably concentric with the axis of rotation, so that the at least one boundary surface is curved multiple times along the at least one course in the axial direction and the boundary surface has a predetermined waviness, which can be expressed in particular as a runout of a predetermined value. Further preferably, the boundary surface is continuous and / or kink-free. If the at least one boundary surface has a plurality of multiply curved courses, the result is that these are preferably concentric with one another and correspondingly spaced from one another in the radial direction.

[0014] In the case of fan wheels designed according to the invention, it has been shown that the deliberately misshapen or corrugated boundary surfaces are advantageous because the pulsing on the fan wheel caused by the axial runout or the course is interrupted by the waves or the waviness, so that the pulsing does not result in a sound emission or in a lower sound emission.

[0015] In the radial direction, the at least one boundary surface can be formed independently of the contours in the circumferential direction and thus, for example, have a substantially flat or frustoconical basic shape. Since the boundary surface is preferably formed without any jumps, this results in it being curved along a contour extending in the radial direction due to the contour in the circumferential direction, or in its free-form form, whereby the waviness in the circumferential direction or the axial runout along a path concentric with the rotation axis is decisive for the sound emissions generated by the rotation.

[0016] Since the axial runout on fan wheels is measured precisely on annular paths concentric with the rotation axis, a predetermined value for the axial runout as a measure of the predetermined waviness results for a fan wheel designed according to the invention, in particular along the path.

[0017] An advantageous further development of the fan wheel provides that the corrugated boundary surface, ie at least one of the boundary surfaces or the boundary surface formed by the first surface and / or the second surface and / or the third surface, has an edge contour which delimits the fan wheel radially outwards and runs around the axis of rotation in a ring shape, which corresponds to one of the courses or one course.

[0018] The corrugated boundary surface, i.e., at least one of the boundary surfaces or the boundary surface formed by the first surface and / or the second surface and / or the third surface, can have precisely one or more profiles. If multiple profiles are provided, these are—as already explained—particularly concentric to one another and spaced radially.

[0019] In the event that the corrugated boundary surface has a plurality of profiles which are in particular concentric with one another and spaced apart in the radial direction, it is further preferably provided that the profiles in the circumferential direction around the axis of rotation have an identical or a different number of local maxima and / or local minima with identical or different height differences to the respective immediately adjacent extreme values.

[0020] The base disc and the blades are preferably integrally formed, ie materially bonded to one another.

[0021] As is usual with blades extending axially from a base plate, which can also be referred to as vanes, the blades each have a blade inlet height on the radial inside and a blade outlet height on the radial outside. Accordingly, a pumped fluid can enter radially inside a fluid channel formed by two adjacent blades and circumferentially delimited by them and exit radially outside.

[0022] A variant has proven particularly advantageous in which the local maxima and / or the local minima of the at least one profile have a local height difference of 2 to 40%, preferably 7 to 35%, more preferably 12 to 30%, even more preferably 17 to 25%, of the blade outlet height to immediately adjacent extreme points, ie in the case of local maxima to the immediately adjacent local minima and in the case of local minima to the immediately adjacent local maxima.

[0023] In other words or alternatively, a vertex determined by the local maximum or the local minimum preferably has a height difference of 2 to 40%, preferably 7 to 35%, more preferably 12 to 30%, even more preferably 17 to 25%, of the blade outlet height to a reference plane from which the course is defined.

[0024] It has also been found that the ratio of the waves on the boundary surface to the number of blades influences the resulting noise and can potentially amplify it if the ratio is unfavorable. In order to avoid such an amplification of the noise, it is further preferably provided that the fan wheel has a first number of blades and the at least one profile determines a second number of local maxima and / or local minima or a second number of waves, wherein the first number and the second number do not have a common divisor. If a plurality of profiles are provided, the second number of the profiles can differ from one another, wherein preferably the first number and each of the second numbers do not have a common divisor.

[0025] For example, this results in an advantageous variant with 7 shafts or 7 maxima (and / or minima) and 17 blades.

[0026] Furthermore, the fan wheel can also have a cover plate which covers the blades at least in sections towards the upper side and extends in the radial direction along the blades and can determine the third surface together with the blades.

[0027] The fan wheel proposed according to the invention is further preferably a radial fan wheel or a diagonal fan wheel.

[0028] A further aspect of the invention relates to a fan with a fan impeller according to the invention, which can accordingly be, in particular, a radial fan or diagonal fan. Furthermore, a blower and, in particular, a blower of a ventilator are also understood to be a fan within the meaning of the invention. In addition to the fan impeller according to the invention, the fan has a housing in which the fan impeller is accommodated. For at least one boundary surface of the fan impeller, the housing has a counter surface assigned to the respective boundary surface, which is spaced from the respectively assigned boundary surface by a gap.

[0029] In particular, the housing has a first counter surface for a boundary surface formed by the first surface of the fan wheel and a second counter surface for a boundary surface formed by the third surface of the fan wheel. Independently of this, the second surface of the fan wheel can also be designed as a boundary surface.

[0030] Also particularly true for the fans according to the invention, it has been shown that the deliberately misshapen or corrugated boundary surfaces are advantageous, since the pulsing caused by the axial runout or the course in interaction with the respective counter surface on the housing is interrupted by the waves or the waviness, so that the pulsing does not result in a sound emission or in a sound emission of a lower order.

[0031] Furthermore, it is preferably provided for the fan that the counter surface or the counter surfaces in the circumferential direction around the axis of rotation, i.e. along all courses running in the circumferential direction, are free of local minima and local maxima, so that the counter surfaces are not wavy or free of waves in the circumferential direction.

[0032] Furthermore, it can be provided that the respective counter surface is designed to correspond in the radial direction to the associated boundary surface, so that an axial distance between the counter surface and the boundary surface is essentially constant over the course of the counter surface in the radial direction. Accordingly, the at least one gap or at least one of the gaps has an essentially constant axial extent along its course in the radial direction. This is particularly advantageous for a counter surface that is associated with a boundary surface formed by the third surface of the fan wheel, since the gap formed here can be referred to as a head gap, which is highly relevant for the efficiency of the fan.

[0033] Advantageously, the housing can be divided into an upper shell and a lower shell, with the fan impeller being arranged in a receiving space formed jointly by the upper shell and the lower shell. The upper shell and the lower shell each form a counter surface, with the counter surface of the lower shell preferably being assigned to a boundary surface formed by the first surface of the fan impeller, and the counter surface of the upper shell preferably being assigned to a boundary surface formed or defined by the third surface of the fan impeller.

[0034] The features disclosed above can be combined as desired, as long as this is technically possible and they do not contradict each other.

[0035] Other advantageous developments of the invention are characterized in the subclaims or are presented in more detail below, together with the description of the preferred embodiment of the invention, with reference to the figures. They show: Fig. 1: a perspective view of a fan wheel; Fig. 2: a side view of a fan wheel; Fig. 3: a perspective view of a base plate of a fan wheel; Fig. 4: a side view of a base plate of a fan wheel; Fig. 5: a comparison of a developed view of the radial outer edges of fan wheels; Fig. 6: a sectional view through a fan with a fan wheel accommodated therein.

[0036] The figures are schematic examples. Identical reference numerals in the figures indicate identical functional and / or structural features.

[0037] In Figure 1 a fan wheel 1 according to the invention is shown in a perspective view, which in Figure 2shown in a side view. The Figures 3 and 4 show a base plate 10 of such a fan wheel 1 also in a perspective ( Figure 3 ) and a side ( Figure 4 ) Opinion.

[0038] For such a Figures 1 to 4 The fan wheel 1 shown basically has a base plate 10 and a plurality of blades 20 extending away from it in the axial direction, wherein the base plate 10 and blades 20 can be connected to one another in one piece or formed integrally with one another.

[0039] With reference to the Figures 3 and 4 It is expressly pointed out that the blades 20 are not shown for the sake of clarity.

[0040] Are impellers or fan wheels in general and also the one in the Figures 1 to 6When the fan wheel 1 shown rotates about its respective rotation axis X, an audible pulsation, i.e. disturbing sound emissions, can occur due to an angular error relative to the rotation axis X or due to faulty axial runout.

[0041] To minimize such noise emissions, the fan wheel according to the invention is designed according to the Figures 1 to 6 that at least one boundary surface, at which the pulsation can arise, for example, through a fluid flowing along the boundary surface or through interaction with the counter surfaces of the housing mentioned below, has a predetermined waviness along a path or along at least one course 30 in the circumferential direction, whereby the pulses that would otherwise arise are broken and the sound emissions are thereby reduced.

[0042] A fan wheel 1, as shown in the Figures 1 to 6As shown, the base plate 10 has a first surface 11 facing the underside B of the fan wheel 1, and a second surface 12 facing the top side A of the fan wheel 1. Furthermore, the blades 20 together define a third surface 23 on their end faces facing the top side A.

[0043] Pulsation can occur in particular on these three surfaces 11, 12, 23, so that at least one of the surfaces 11, 12, 23 and preferably - as shown in the figures - all surfaces 11, 12, 23 are designed as a wavy boundary surface and each have at least one course 30 in the circumferential direction U around the axis of rotation X, which in turn each has at least one local maximum 32 or at least one local minimum 33 so that the respective boundary surface is curved several times in the axial direction along the respective course 30 and has a predetermined waviness.

[0044] The respective surfaces 11, 12, 23 provided as boundary surfaces each have a radially outer edge contour 31, which radially outwardly limits the fan wheel 1 at the respective surface 11, 12, 23. It is advantageous for interrupting the pulsation if - as in the illustrated embodiment - the respective edge contour 31 is designed as a wavy course. This is particularly clear in the Figures 2, 4 and 5 to see, in which it is clearly visible that the edge contours - and with reference to Figure 4 the other courses 30 - do not lie in one plane, but oscillate or fluctuate around a respective neutral plane.

[0045] Tests have shown that the noise emissions are particularly strongly reduced when a height difference D between adjacent extreme points, ie the height difference D of a maximum 32 to an immediately adjacent minimum 33 is 2 to 40%, preferably 7 to 35%, more preferably 12 to 30%, even more preferably 17 to 25% of the blade outlet height H, which is illustrated, for example, by looking at Figures 2 and 5 together.

[0046] In principle, Figure 5 The difference between the fan wheel 1 according to the invention and a conventional fan wheel 5 is illustrated. In the prior art, the fan wheel 5 is usually manufactured with the highest possible precision, thus achieving a high-quality axial runout. Accordingly, the edge contours 51 of the conventional fan wheel 5, as shown in Figure 5are shown as a developed view, in one plane. In contrast, the edge contours 31 of the fan wheel 1 designed according to the invention, also shown as a developed view, clearly show that they fluctuate around a respective plane and have a plurality of maxima 32 and minima 33 or a predetermined waviness.

[0047] In Figure 6 the fan wheel 1 according to the invention is inserted into a housing 4, wherein the fan 2 formed thereby is shown in a sectional view.

[0048] Specifically, the housing 4 is divided into an upper shell 41 and a lower shell 42, which together form a receiving space in which the fan wheel 1 is rotatably mounted and can be driven about the rotation axis X.

[0049] The housing 4 has a first counter surface 43 for the boundary surface formed by the third surface 23 of the fan wheel 1 and a second counter surface 44 for the boundary surface formed by the first surface 11 of the fan wheel 1. A gap 45, 46 is formed between the respective boundary surface and the counter surface 44, 45, wherein the gap 45 can be described as a head gap that is particularly relevant for the efficiency of the fan 2, since the head gap is intended to prevent the backflow of the conveyed fluid from the downstream side (bottom side B) to the inflow side (top side A).

[0050] It is preferably provided, as in the illustrated embodiment, that the counter surfaces 43, 44 are free of waves in the circumferential direction U.

[0051] The invention is not limited to the preferred embodiments described above. Rather, a number of variants are conceivable that utilize the presented solution even in fundamentally different embodiments.

Claims

1. Fan wheel (1) for rotation about a rotation axis (X), comprising a base disc (10) with a first surface (11) facing a bottom side (B) in the axial direction and a second opposite surface (12) facing a top side (A), and comprising a plurality of blades (20) which extend from the second surface (12) of the base disc (10) in the axial direction towards the top side (A) and together span a third surface (23) towards the top side (A), characterized in thatthe first surface (11) and / or the second surface (12) and / or the third surface (23) are / is each a corrugated boundary surface of the fan wheel, which has at least one local maximum (32) and / or local minimum (33) in the axial direction along at least one profile (30) in the circumferential direction (U) around the axis of rotation (X), so that the at least one boundary surface is curved several times along the at least one profile (30) in the axial direction and has a predetermined waviness.

2. Fan wheel according to claim 1, wherein the corrugated boundary surface has an edge contour (31) which delimits the fan wheel (1) radially outwardly and runs annularly around the axis of rotation (X), which corresponds to one of the profiles (30).

3. Fan wheel according to claim 1 or 2, wherein the corrugated boundary surface has exactly one course (30) or several courses (30) which are in particular concentric to one another and spaced apart in the radial direction (R).

4. Fan wheel according to claim 1 or 2, wherein the corrugated boundary surface has a plurality of courses (30) which are in particular concentric with one another and spaced apart in the radial direction (R), wherein the courses (30) in the circumferential direction (U) around the axis of rotation (X) have an identical or a different number of local maxima and / or local minima with identical or different height differences to the respectively immediately adjacent extreme values.

5. Fan wheel according to one of the preceding claims, wherein the blades (20) have a blade outlet height (H) radially outward in the axial direction (X) and wherein the local maxima and / or local minima of the at least one profile (30) have a local height difference (D) of 2 to 40% of the blade outlet height (H) to immediately adjacent extreme points.

6. Fan wheel according to one of the preceding claims, wherein the fan wheel (1) has a first number of blades (20), the at least one profile (30) determines a second number of local maxima and / or local minima and the first number and the second number have no common divisor.

7. Fan wheel according to one of the preceding claims, wherein the blades (20) determine the third surface (23) together with a cover plate which covers the blades (20) towards the upper side (A) at least in sections and extends in the radial direction (R) along the blades (20).

8. Fan wheel according to one of the preceding claims, wherein the fan wheel (1) is a radial fan wheel or a diagonal fan wheel.

9. Fan (2) with a fan wheel (1) according to one of the preceding claims and a housing (4) in which the fan wheel (1) is accommodated, wherein the housing (4) has, for at least one boundary surface of the fan wheel, a counter surface (43, 44) assigned to the respective boundary surface, which is spaced from the respectively assigned boundary surface by a gap (45, 46).

10. Fan according to the preceding claim, wherein the counter surfaces (43, 44) are free of local minima and local maxima in the circumferential direction around the rotation axis (X), so that the counter surfaces (43, 44) are free of waves in the circumferential direction (U).

11. Fan according to one of the two preceding claims, wherein the respective counter surface (43, 44) is formed in the radial direction corresponding to the associated boundary surface, so that an axial distance of the counter surface (43, 44) to the boundary surface is constant over the course of the counter surface (43, 44) in the radial direction (R).

12. Fan according to one of the preceding claims 9 to 11, wherein the housing (4) is divided into an upper shell (41) and a lower shell (42), the fan wheel (1) is arranged in a receiving space formed jointly by the upper shell (41) and the lower shell (42), and the upper shell (41) and the lower shell (43) each form a counter surface (43, 44).

Images