Axial fan with increased rotor diameter

Abstract

An axial fan for use with a wall ring plate includes a housing having an inlet region and a rotor. The rotor has an increased rotor diameter compared to a standardised rotor diameter. On the inlet side, the inlet region has a tapered section that narrows in an arched manner in a cross-sectional view from an inlet diameter to a wall ring diameter. The axial width and radial length of the tapered section are formed in a predetermined ratio.

Claims

1. An axial fan and an integral wall ring plate, the axial fan comprising a motor, a one piece housing includes two ends with three axially adjacent abutting regions, an inlet region, a cylindrical region and an outlet diffuser region, the inlet region is at one end extending from the wall ring plate and the outlet diffuser region is at the other end and the cylindrical region is extending immediately between the inlet and outer regions, and a rotor which can be driven by the motor, the rotor has a hub that receives the motor, wherein the housing, on the inlet side, has an outer housing dimension (D1) and the rotor has an increased non-standard sized rotor diameter (D.sub.L) as compared with a rotor diameter (D_standard) which is standardized based on the standard series R20 of the DIN standard 323 or the ISO 3 standard, so that a ratio of D.sub.1/D.sub.L is less than a ratio of D.sub.1/D.sub.standard; the rotor diameter (D.sub.L) is increased by the factor g with a constant outer housing diameter (D.sub.1) as compared with the standardized rotor diameter (D.sub.standard), wherein a factor g is defined in a range of g.sub.min to g.sub.max, wherein
g.sub.min=−0.00008×D.sub.standard+1.1 and
g.sub.max=−0.00022×D.sub.standard+1.34; on the inlet side, the inlet region has a tapered section that narrows in an arched manner in a cross-sectional view from an inlet diameter (D.sub.A) to a wall ring diameter (D.sub.WR) that defines the cylindrical region, an axial end of the tapered wall section at approximately the wall ring diameter in the direction of flow forms a vertical plane coinciding substantially with a front edge of the hub, such that, axially the hub, with its front edge and a portion of fan blades, extend axially along the cylindrical region defined by the wall ring diameter, an axial width (b) and a radial length (a) of the tapered section form a ratio of (a)/(b) in a range from 0.4 to 0.6; the motor is configured as an external rotor motor, a motor replacement insert is arranged inside the hub and different motors with different motor diameters can be connected to the insert.

2. The axial fan according to claim 1, wherein the wall ring plate has outer dimensions and is round or rectangular, wherein in the case of a rectangular configuration, its shorter side edge and in the case of a round configuration its total diameter corresponds to the outer housing dimension (D.sub.1).

3. The axial fan according to claim 1, wherein the wall ring plate is integrally formed on the housing.

4. The axial fan according to claim 1, wherein, on the inlet side, the inlet region of the housing has an outer edge region extending from the outer housing dimension (D.sub.1) to the inlet diameter (D.sub.A) in a radial manner over a length (c), the outer edge region is followed by the tapered section, as viewed in the direction of axial flow.

5. The axial fan according to claim 4, wherein the outer edge region extending radially over the length (c) is determined from the difference of the outer housing dimension (D.sub.1) and the inlet diameter (D.sub.A).

6. The axial fan according to claim 4, wherein a reinforcement web is formed between the outer edge region and the tapered section.

7. The axial fan according to claim 1, wherein the factor g is defined in the range of g.sub.min to g.sub.max, wherein
g.sub.min=−0.00008×D.sub.standard+1.1 and
g.sub.max=−0.00022×D.sub.standard+1.088.

8. The axial fan according to claim 4, wherein the housing has an inlet geometry in which a ratio j of the axial width (b) to the outer edge region extending radially vertically over the length (c) is defined in a range of j.sub.min to j.sub.max, wherein
j.sub.min=−0.0047×D.sub.standard+6.5225, and
j.sub.max=−0.0054×D.sub.standard+8.8135.

9. The axial fan according to claim 8, wherein the ratio j is defined in the range j.sub.min to j.sub.max, wherein
j.sub.min=−0.0047×D.sub.standard+6.5225, and
j.sub.max=8.

10. The axial fan according to claim 1, wherein the rotor comprises a plurality of blades, with a winglet being integrally formed on the radial outer region of each blade.

Description

DRAWINGS

(1) FIG. 1 shows a front view of an axial fan with wall ring plate;

(2) FIG. 2 shows a three-dimensional, partially sectioned view of one half of the axial fan from FIG. 1;

(3) FIG. 3 shows an alternate embodiment of the axial fan from FIG. 2; and

(4) FIG. 4 shows a diagram of the pressure number achieved according to the disclosure.

DESCRIPTION

(5) The figures are schematic examples. The same reference numerals designate the same parts in all views. The outside dimensions and diameters designated above and in the claims as D.sub.1, D.sub.A, D.sub.L, D.sub.WR, D.sub.standard are characterized in the figures and in the following by underlining, i.e., as D_1, D_A, D_L; D_WR, D_standard.

(6) FIG. 1 shows a front view of a low-pressure axial fan 1 with a rectangular wall ring plate 9 integrally formed thereon, which plate has side edge lengths D_2 and D_1 (D1>D2), wherein the top view is in the direction of flow, and the rotor 20 constructed with five rotor blades 2 extending radially outward from the hub 6 is apparent at the center of the axial fan 1. The wall ring plate 9 has standard dimensions and forms a structural unit with the axial fan 1 which makes possible a direct exchange with existing systems, for example, in condensers, heat exchangers, refrigerating systems and the like.

(7) FIG. 2 shows one half of the axial fan from FIG. 1 in a three-dimensional, partially sectioned view. It is understood that the half opposite the axial central line is configured as an identical mirror image. The axial fan 1 comprises a motor 8 configured as an external rotor arranged inside the hub 6 and connected to the rotor 20 by a motor replacement insert 7 which fits the dimension of the motor 8. The motor replacement insert 7 can be detachably fastened to the hub 6. The motor 8 drives the hub 6 and therefore the rotor 20 via the motor replacement insert 7.

(8) The housing 10 of the axial fan 1 comprises an inlet region 11 viewed in the direction of flow from left to right with a maximum outside housing dimension D_1, a tapered section 4 which is arched in a partially elliptical manner in cross section, a middle section 14 extending axially horizontally, and an outlet region 12 constructed with a diffusor 3. The opening angle “alpha” of the diffusor 3 is approximately 12 degrees. The total axial length of the axial ventilator 1 is designated as h. The rotor 20 is arranged in the axial fan 1 substantially at the level of the middle section 14, wherein a vertical plane on the boundary between the middle section 14 and the diffusor 3 intersects the rotor 20 in a radial direction. Each blade 2 of the rotor 20 has a winglet 21 extending along the axial outer edge at its radial end section.

(9) The rotor 20 furthermore comprises a rotor diameter D_L which is increased in comparison with a standardized rotor diameter D_standard based on DIN 323 and ISO 3, so that the ratio of D_1/D_L is smaller than the ratio of D_1/D_standard. The exit surface of the axial fan 1 is increased by the increase in the diameter of the rotor 20 in comparison with the standardized rotor diameter D_standard, as a result of which its dynamic exit losses are reduced and the efficiency is increased. In the embodiment shown, the rotor diameter D_L is approximately 10% greater than the standardized rotor diameter D_standard.

(10) In the inlet region 11, on the inlet side, an outer edge region 5 extending from the outside housing diameter D_1 to the inlet diameter D_A in a radially vertical manner over a length c/2 is formed, which is followed by the tapered section 4, as viewed in the direction of axial flow. The radial length c of the outer edge region 5 results from the difference of the outer housing dimension D_1 and the definable inlet diameter D_A. The axial width b and the radial length a of the tapered section 4 form a ratio of a/b which in the embodiment shown corresponds to approximately a value of 0.5. The lengths a and b are measured taking into account the wall thickness of the housing 10. The length b ends at the point at which the housing 10 merges into the totally horizontal middle section 14, i.e., no arched form of the tapered section 4 can be identified. The length a ends at the point at which the housing 10 merges into the totally vertical outer edge area 5, i.e. no arched form of the tapered section 4 can be identified. The axial end of the tapered section 4 in the direction of flow forms a vertical plane which coincides substantially with the front edge of the hub 6 in the embodiment shown.

(11) FIG. 3 shows, as an alternative to the embodiment according to FIG. 2, an embodiment in which all features are identical; however, a reinforcement web 13 for reinforcing the inlet region 11 is additionally formed on the housing 10 of the axial fan 1 in the inlet region 11 in-between, i.e., in the transition from the outer edge region 5 to the tapered section 4. In this embodiment, the measure a of the tapered section 4 can be determined even more easily since it extends up to the axial inside of the axially horizontal reinforcement web 13.

(12) FIG. 4 shows the reduction of the pressure number ψ of the axial fan 1 according to the disclosure against those of the prior art with respect to the standardized rotor diameter D_standard. The static efficiency optimum of the axial ventilator 1 according to the invention is surprisingly at a pressure number value of ψ≤−0.0003×D_standard+0.425, i.e., on or below the boundary curve sketched in the diagram, whereas the rotors according to the prior art, with and without a follower guide wheel, are always above the boundary curve.

(13) The disclosure is not limited in its execution to the above-indicated, preferred exemplary embodiments. Rather, a number of variants are conceivable which make use of the presented solution even with embodiments of a fundamentally different design. For example, the number of blades of the rotor is not limited to five and may instead range from 3 to 13, in particular 4 to 7. Furthermore, a follower guide wheel which is not shown in the figures can be used to optimize the flow and a protective grid can be used as contact protection.