Impeller wheel for a ventilator

The impeller wheel is rotatably supported about a central axis and has a hub on which vanes are arranged. The vane has across its radial length at least similar profiled sections, viewed in cylindrical section through the vane. The radial outermost profiled section which is positioned on a cylindrical enveloping surface of the impeller wheel has a greater displacement relative to the neighboring profiled section than this neighboring profiled section to its neighboring profiled section. The impeller wheel can also be provided on the radial outer edge with at least one projecting flow element whose axial height has a maximum in the area of the leading edge and of the trailing edge of the vane. The impeller wheels, while having a simple constructive configuration, provide a great noise reduction in operation of the ventilator.

BACKGROUND OF THE INVENTION

The invention concerns an impeller wheel for a ventilator that is rotatably supported about a central axis and comprises a hub on which vanes are arranged The invention further relates to an impeller wheel for a ventilator, comprising a hub from which vanes are projecting that are provided with at least one projecting flow element at the radial outer edge.

Ventilators and impeller wheels are known (DE 20 2004 005 548 U1) in which vanes are projecting from the hub of the impeller wheel that are of a twisted configuration and are provided on the radial outer edge with flow elements. The vanes have approximately the cross-sectional shape of an airplane wing. The flow elements at the outer edge of these vanes have an analog extension. In this way, the outer edge of the flow elements extends approximately parallel to the cross-sectional topside and bottom side of the corresponding vane. In the area of the leading edge and trailing edge of the vanes the axial height of the flow elements decreases to almost 0. With such a configuration, a noise generation upon operation of the impeller wheel or the ventilator is to be at least reduced. The flow elements cause increased resistance for the leakage flow that flows about the radial outer edges of the vanes from the pressure side to the suction side.

The invention has the object to design an impeller wheel of the aforementioned kind in such a way that with a simple constructive configuration a high noise reduction in operation is achieved.

SUMMARY OF THE INVENTION

This object is solved in accordance with the invention in regard to the impeller wheel of the afore mentioned kind in that the vane about its radial length has at least similar profiled sections, viewed in cylindrical section through the vane, and in that the radial outermost profiled section that is positioned in a cylindrical enveloping surface of the impeller wheel has a greater displacement relative to the neighboring profiled section than this neighboring profiled section to its neighboring profiled section.

This object is further solved in accordance with the invention in regard to the impeller wheel of the afore mentioned kind in that the axial height of the flow element has a maximum in the area of the leading edge and the trailing edge of the vane.

In the impeller wheel according to the invention, the vane has across its radial length at least similar profiled sections, viewed in cylindrical section through the vane. The radial outermost profiled section that is positioned in the cylindrical enveloping surface of the impeller wheel is displaced relative to the neighboring profiled section. This displacement is greater than the displacement that this neighboring profiled section has to its neighboring profiled section. In this way, the vane is designed such that the vane, beginning at the hub of the impeller wheel, has across its radial length profiled sections that, at least across a portion of this radial length, are displaced relative to each other. The displacement in this area between the individual profiled sections is approximately identical. The radial outermost profiled section, however, is displaced by a value that is greater, preferably multiple times greater, than the displacement of the profiled sections in the aforementioned remaining radial area of the vane. In this way, the vane can be shaped in a constructively simple way such that the air can substantially flow past the radial outer profiled section without impairment, and a noise reduction is achieved in this way. The profiled section displacement at the radial outer edge of the vanes can be achieved in a simple way by the described shaping of the vane.

In this connection, the vane is designed such that across its radial length it has approximately similar profiled sections. The cross-sectional shapes of the vane are thus designed similarly so that even the radial outermost profiled section with respect to its cross-sectional shape does not differ significantly from the cross-sectional shapes of the other profiled sections in the longitudinal direction of the vane. As a result of the configuration in accordance with the present invention, the vane can be constructed in a very simple way because the profiled section of the vane is simply displaced, wherein displacement can be done by translatory and/or rotatory movement. This translatory and/or rotatory displacement of the profiled section enables a simple calculation and construction of the vane that, in this way, can be matched optimally to the application in question.

Advantageously, the profiled sections that follow the outermost profiled section at at least approximately identical spacings each have at least a displacement relative to each other that is smaller than the displacement between the outermost profiled section and the profiled section neighboring it.

Advantageously, the spacing of the profiled sections laid through the vane is greater than the radial width of the radial outermost profiled section of the vane that is formed by the displacement of the outermost profiled section. This end area has as a result of the greater displacement also a greater incline than the remaining part of the vane in which the other profiled sections, in particular the profiled section that is neighboring the outermost profiled section, are located.

The profiled sections that are following the outermost profiled section at at least approximately identical spacings each have at least partially a displacement relative to each other that is smaller than the displacement between the outermost profiled section and the profiled section neighboring it.

The spacing of the profiled sections is greater than the width of the end area, measured in radial direction, which width is formed by the displacement of the outermost profiled section, wherein the end area has a greater incline than the remaining part of the vane.

At least the outer profiled section of the vane is displaced translatorily and/or rotatorily relative to the neighboring profiled sections.

The radial outer profiled section has a different profile shape than the remaining profiled sections.

The leading edge of the vane across its length is at least partially concavely shaped.

The trailing edge of the vane across its length is at least partially convexly shaped.

The trailing edge of the vane is provided with teeth at least across a portion of its length.

The transition area between the leading edge and the radial outer edge of the vane in the rotational direction of the vane projects relative to the transition area where the leading edge passes into the hub.

The vane is embodied as a twisted vane.

The vane has a curved shape.

Also, the impeller wheel according to the invention is characterized in that the axial height of the flow element has a maximum in the area of the leading and trailing edges of the vane. Advantageously, the height of the flow element decreases in the direction toward the center of the vane. Because of this configuration of the flow element, an excellent noise reduction upon use of the impeller wheel as well as an optimal impairment-free flow of the air from the pressure side to the suction side are realized so that noise reduction is favorably affected.

In an advantageous configuration, the ratio of the axial height of the flow element to the axial thickness of the vane decreases from the maximum in the direction toward the center of the vane. The height of the flow element can decrease down to 0 in the area between the leading edge and the trailing edge of the vane.

The flow element together with the wall surrounding the impeller wheel forms a nozzle-shaped flow gap that connects the pressure side with the suction side of the impeller wheel and through which the air flows substantially unimpaired.

The flow element or the radial outer wall of the vane has a large inlet area at the pressure side.

The ratio of the axial height of the flow element to the axial thickness of the vane in the area of the flow element decreases beginning at and away from the leading edge and/or the trailing edge of the vane.

The leading edge of the vane across its length is at least partially concavely shaped.

The trailing edge of the vane across its length is at least partially convexly shaped.

The trailing edge of the vane is provided with teeth at least over a portion of its length.

The transition area between the leading edge and the radial outer edge of the vane is projecting in the rotational direction relative to the transition area between the leading edge and the hub.

The vane has a twisted shape.

The vane has a curved shape.

Further features of the invention result from the additional claims, the description, and the drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS

The ventilator has a housing1with a cylindrical wall2that surrounds a conveying passage3. In the conveying passage3the impeller wheel4is provided whose hub5is rotatably supported, as is known in the art. The impeller wheel4is rotatably driven in the direction of arrow6counterclockwise by means of a drive4a.

Six vanes7, for example, project form the hub5and extend into the vicinity of the wall2. The air flows, as shown inFIG. 6, between the radial outer edge of the vanes7and the inner side of the wall2from the pressure side9substantially unimpaired to the suction side8of the impeller wheel4.

In order for the noise developed in operation of the ventilator to be in a frequency spectrum that is pleasing to the human ear, it is advantageous when the vanes7are non-uniformly distributed about the circumference of the hub5.

Of course, the impeller wheel4can also be designed such that the vanes7are uniformly distributed about the circumference of the hub5.

The vanes7have each in rotational direction6a leading edge10at the front as well as a trailing edge11rearwardly positioned in the rotational direction6. The leading edge10, viewed in axial direction of the impeller wheel4, is of a crescent shape, i.e., it has a concave extension. The leading edge10extends away from the hub5to the outer edge12that extends in the circumferential direction of the impeller wheel4. The outer edge12has a radial spacing13(FIG. 6) from the housing wall2. This spacing is selected such that the leakage flow is as small as possible and minimal noise is developed.

Advantageously, the area14(FIG. 2) where the leading edge10intercepts the outer edge12, in rotational direction6of the impeller wheel4, is positioned father forwardly than the connecting area of the leading edge10at the wall of the hub. When a radial line is drawn through the axis of the impeller wheel4and through this corner area14, the connecting area of the leading edge10at the hub wall, viewed in axial direction, is behind this radial line in rotational direction. With such a configuration of the vanes7a noise reduction in operation of the ventilator and improvement of the separation behavior at the trailing edge is observed.

The trailing edge11of the vane7extends at least about a portion of its length in a convex shape. This convex shape can be provided from the hub5up to the outer edge12of the vane. However, it is also possible to provide the convex shape only about a portion of the length of the trailing edge11of the vane7. For example, this convex course can be provided only in the area of the trailing edge11that adjoins the outer edge12.

In the illustrated embodiment the trailing edge11is provided about a portion of its length with teeth15that taper in the direction toward their free end. The teeth15can have identical contour shape. In a preferred embodiment, the teeth15are designed such that their ends that advantageously taper to a point extend up to a convexly extending enveloping line16(FIGS. 4 and 7). This enveloping line16can advantageously be a continuation of the area of the trailing edge11that is not provided with teeth.

The teeth15can have along the trailing edge11also different contour shapes and/or different length. With appropriate selection of the design of the teeth15, the noise development of the ventilator can be optimally adjusted to the respective application.

The vanes7are configured as twisted vanes.

On the radial outer edge12each vane7in the embodiment according toFIGS. 1 to 6is provided with a flow element17that extends advantageously about the entire length of the outer edge12between the leading edge10and the trailing edge11. The flow elements extends on the outer edge12to the suction side8of the vane7. However, it is also possible that the flow element17extends on the suction side8as well as on the pressure side9. Also, it is possible that the flow element17is projecting only in the direction toward the pressure side9.

The flow elements17are advantageously configured monolithically together with the vanes7but, in principle, can also be components separate from the vanes that are then attached in a suitable way to the vanes.

The flow element17has in the area of the leading and the trailing edges10,11of the vane7its greatest height h, respectively, measured in axial direction18of the impeller wheel4(FIG. 5). InFIG. 5, the flow element17as well as the profile of the corresponding vane7are illustrated at the level of the flow element17. The axial height h of the flow element17decreases beginning at and away from the leading edge10or the trailing edge11, respectively, until the flow element17in the area between the two edges10,11reaches the height 0 or approximately 0. This area can be located at half the width of the vane7. The vane7has in the area of the flow element17the axial thickness d. In the remaining area the vane7can have a different axial thickness.

The axial height h of the flow element17as well as the axial thickness d of the vane7are matched to each other such that the ratio h/d decreases beginning at and away from the leading edge10as well as the trailing edge11, as indicated by the dashed line19inFIG. 5. In the area in which the axial height h of the flow element17is approximately 0, this ratio h/d is at a minimum.

Depending on the application, the flow element17can also be designed such that its minimal axial height is not positioned at half the width of the vane7. It is important that the indicated ratio h/d decreases away from the leading edge10or the trailing edge11. With such a configuration of the vane with flow element an excellent noise reduction in use of the ventilator results.

As can be seen inFIG. 5, the vane7has an airplane wing profile shape. In the area of the leading edge10, the vane7is rounded while in the area of the trailing edge11it tapers approximately to a point. In the area between the two edges10,11the vane7can also have an approximately constant cross-sectional thickness.

In the preferred one-part configuration of vane7and flow element17, the vane7has at the pressure side9a large inlet area20(FIG. 6) at the transition from the vane7to the flow element17, preferably with a large radius27. This excellently contributes to a noise-reduced operation of the ventilator.

The flow element17is designed such that its axial extension, beginning at the leading edge10of the vane7, across a very short area increases strongly until the flow element has its greatest axial height h with minimal spacing relative to the leading edge10. Similarly, the axial height h of the flow element17increases, beginning at the trailing edge11of the vane7, across a very short area strongly until the flow element, with minimal spacing from the trailing edge10in this area, has its greatest axial height h that decreases in the direction of the center of the vane7. As a result of this configuration the flow element17has a completely different course than the vane7in the area of the flow element17.

FIGS. 7 to 11show a twisted vane7which instead of the flow element17in the radial outer area has such a configuration that despite the missing flow element17the same effect is obtained as with the vane with flow element. This is achieved by a special configuration of the vane which will be explained in the following in more detail.

As shown inFIGS. 7 and 8, the vane7has about its radial length at the same spacings the profiled sections24.1to24.7that have a similar cross-sectional configuration. As in the preceding embodiment, the vane7has an airplane wing profile shape in which the vane7in the area of the leading edge10is rounded and in the area of the trailing edge11is tapering approximately to a point.

The outer edge12of the vane7facing the housing wall2is designed such that the radial outer profiled section of the vane is displaced in a direction toward the suction side8. InFIG. 7, across the length of the vane7different profiled sections21,21.1, to21.7are indicated. The profiled sections are cylindrical sectional views of the vane7. The profiled sections21.1to21.7are provided at the same spacings in radial direction of the vane7. The profiled section21.7(FIG. 7) is provided at the hub5of the impeller wheel4. It can be seen that all profiled sections21to21.7have a similar cross-sectional shape, in the embodiment an airplane wing profile shape. The profiled sections, beginning at the inner profiled section21.7and viewed in radial direction of the vane7, are arranged so as to be displaced relative to each other.

InFIG. 8the situation is illustrated that this displacement of the profiled sections up to the cylindrical enveloping surface22of the impeller wheel4is continued in the usual way. In this case, the radial outermost profiled section in the enveloping surface22would assume the position that is indicated inFIG. 8by the dashed line21.1. In the present embodiment, however, this radial outermost profiled section21is displaced in the direction toward the suction side8such that the profiled section21has a relatively large displacement relative to the neighboring profiled section21.2. The displacement between this radial outermost profiled section21and the neighboring profiled section21.2is greater than the displacement between the profiled section21.2and the profiled section21.3neighboring it. As a result of this significant displacement between the outermost profiled section21and the neighboring profiled section21.1there is a radial outer end area20(FIG. 9) that has a substantially greater incline than the remaining part of the vane in which part the profiled sections21.2to21.7are located.

The profiled sections are designed such that the spacing of the profiled sections relative to each other is greater than the width25(FIG. 9) of the radial outer end area20that is formed by the displacement of the outermost profiled section21. Since the displacement between the radial outermost profiled section21and the neighboring profiled section21.2is greater, preferably significantly greater, than the displacement between the profiled sections21.2and21.3, the radial outer end area20has a greater incline than the remaining part of the vane7where the profiled sections21.1221.7are extending.

Basically, it is sufficient when only the outermost profiled section21is displaced in the direction toward the suction side8relative to the neighboring profiled section or profiled sections.

The radial end area20(FIG. 9) that is resulting from the displacement of the profiled section or profiled sections generates an effect that is similar to that of the flow element17of the preceding embodiment and that is achieved by the profiled section displacement alone.

In the embodiment, the profiled sections21to21.7have a similar cross-sectional configuration. The radial outer profiled section21can have a different profiled section shape than the remaining profiled sections21.2to21.6. Accordingly, by influencing the position of the respective profiled sections relative to each other, the vane7can be optimized optimally to the required application with regard to efficiency and/or noise reduction.

In the described and illustrated embodiment the displacement of the profiled section is realized in the direction toward the suction side8. The displacement can however also be toward the pressure side9.

In other respects, the vane7is of the same configuration as in the preceding embodiment.

In order to achieve a flow24through the gap as unhindered as possible in the area between the flow element17or the end area20and the inner side of the housing wall2, the flow element17or the end area20, viewed in the axial direction of the impeller wheel4(FIG. 4), has a great radius of curvature27.

Optimal gap flow24is assisted in that the flow gap26(FIG. 6) between the flow element17or the end area20and the housing wall2is tapering from the pressure side9in the direction toward the suction side8. The flow gap26is designed like a nozzle; this contributes to an unimpaired flow of the air for noise reduction through the flow gap26.

The displacement of the profiled sections of the vane7described in connection with theFIGS. 7 to 11is realized in the illustrated embodiment by translatory and rotatory movement. InFIG. 11, the different profiled sections are illustrated in a projection onto the drawing plane.FIG. 11shows that these profiled sections are not only displaced by translation but also by rotation relative to each other. It can be seen that the radial inwardly positioned profiled sections21.7to21.5extend steeper than the radial outwardly positioned profiled sections21to21.4.FIG. 11also shows that by this displacement of the profiled section across the radial length of the vane7the shape of this vane can be determined very simply by the designer and can be matched to the situation of use.

The specification incorporates by reference the entire disclosure of German priority document 10 2010 034 604.7 having a filing date of Aug. 13, 2010.