Single-piece Fan Wheel

Abstract

The invention relates to a blower wheel (1) in a one-piece design having a bottom disk (12) and a cover disk (11) between which a blade ring is formed having multiple blower wheel blades (13) disposed in the circumferential direction at a spacing from one another, wherein the bottom disk (12) defines a maximum radial diameter da and the cover disk (11) forms an axial intake opening (25) having a diameter di, wherein the cover disk (11) extends radially outwards from the circumferential edge (14) which forms the intake opening (25) and has a maximum outer diameter dt, and wherein an outer diameter ratio dt/da is defined in a range from 0.6 to 0.8.

Description

[0001] The invention relates to a one-piece blower wheel for use in a blower, particularly in a gas-air premix blower.

[0002] Blower wheels for use in a gas-air premix blower are known from prior art and comprise a bottom disk, a hub for connecting to a rotor of an electric motor, and optionally a cover disk. Where a cover disk is provided, a blade ring of blower wheel blades disposed at a spacing from one another in the circumferential direction extends in the axial direction up to the cover disk, forming a radial blowout section.

[0003] When in operation, oscillatory interaction occurs between the rotor which drives the blower wheel and the blower wheel itself, which could have an adverse influence on noise characteristics and air output of the blower wheel. It was found in practice that a pumping movement which has an adverse effect on air output and noise characteristics is initiated at a specific order, particularly the 8th order, of the natural torsional frequency of the rotor. Measurements have confirmed that the sound power increases significantly at a speed of the blower wheel that is at the natural torsional frequency of the rotor.

[0004] It is therefore the object of the invention to provide a blower wheel that is less susceptible to the pumping movement, particularly to axial vibration in the area of the outer diameter due to influences from the driving rotor. Its fluidic properties (air output, speed, efficiency) and simple and economical manufacturing are to be maintained.

[0005] This object is achieved by the combination of features according to claim 1.

[0006] According to the invention, a one-piece design of a blower wheel is proposed having a bottom disk and a cover disk between which a blade ring is formed having multiple blower wheel blades disposed at a spacing from one another in the circumferential direction. The bottom disk defines a maximum radial diameter da. The cover disk forms an axial intake opening having a diameter di and has a maximum outer diameter dt. The cover disk extends radially outwards from the circumferential edge that forms the intake opening. An outer diameter ratio dt/da is defined in a range from 0.6 to 0.8, more preferably in a range from 0.66 to 0.77.

[0007] Regardless of the blower wheel diameter, the advantageous effects of reduced axial vibration during the natural torsional frequency and thus reduced acoustic emissions are always achieved in a blower wheel that is characterized in that the separation of bottom and cover disks at a ratio of the outer diameters is set to a value of 0.69 or 0.74 with a respective maximum variation of .+-.0.03. The respective value can therefore generally be applied.

[0008] Small changes of the ratio of the outer diameters dt/da have a substantial influence on the interaction between the rotor and the blower wheel and particularly with respect to exciting axial vibrations. The range according to the invention of the ratio of outer diameters dt/da is small and even characterized by a specific selection of values.

[0009] The one-piece or single-part design of the blower wheel allows easy demoldability during manufacturing by injection molding and good injection molding properties. The blower wheel can also be produced cost-effectively using a 3D printing process.

[0010] In an advantageous embodiment of the blower wheel, the blower wheel blades start from the circumferential edge of the cover disk and extend radially outwards, and the axial front sides of the blower wheel blades are uncovered and extend radially outwards on a side opposite the bottom disk and comprise a free end each.

[0011] Furthermore, a design is advantageous in which the cover disk, viewed in a radial section, is curved in a funnel-shaped manner and forms an inlet nozzle.

[0012] To achieve positive injection molding properties and a reduced tendency to vibration excitation, a design of the blower wheel is favorable in which the cover disk has a thickness t at the circumferential edge which corresponds to a thickness t of the blower wheel blades. The same wall thicknesses generally are a preferred solution, such that it is further favorable that the bottom disk, at least at its radially outer edge, has a thickness t that corresponds to the thickness t of the blower wheel blades.

[0013] In a further improvement, a radial outer edge of the cover disk finally also has the thickness t of the blower wheel blades. Both the cover disk and the bottom disk can have a constant material thickness t over their overall radial extension.

[0014] Another positive aspect for reducing excitation and acoustic emission of the blower wheel is found in an embodiment in which a ratio of the diameter of the axial intake opening di and the maximum outer diameter dt of the cover disk di/dt is in a range from 0.5 to 0.7. The intake opening therefore makes up a large portion of the entire diameter of the blower wheel, such that the radial extension of the cover disk is small.

[0015] A significant area for axial vibration excitation is the radially outer section of the blower wheel. In an advantageous embodiment for reducing vibration of the blower wheel, the radially outer edges of the blower wheel blades extend in a plane parallel to the axis of rotation and the bottom disk is flush in a plane with the radially outer edges of the blower wheel blades.

[0016] Radially on the inside, a design of the blower wheel is advantageous in which the blower wheel blades transition into the hub of the blower wheel on their radially inner sides. The radially inner edges of the blower wheel blades can extend in an arc-shaped cross section, such that they are rounded towards the intake opening.

[0017] It is furthermore favorable that the outermost radial sections of the cover disk and the bottom disk extend parallel to an axial plane, that is, extend radially outwards in a straight line.

[0018] For manufacturing without a slider, a blower wheel design is favorable in which the bottom disk and the cover disk extend without overlapping relative to one another in an axial top view, as viewed in a projection.

[0019] The invention further includes a blower designed as a gas-air premix blower for delivering a gas-air mixture, having a multi-part blower housing and a motor unit with motor electronics disposed on its outer side, wherein a blower wheel having the features described above is disposed inside said blower housing which, when in operation, draws in air via an intake opening of the blower housing and blows out air via a blowout opening of the blower housing, wherein the motor unit includes a rotor which is in operative connection with the blower wheel.

[0020] Other advantageous further developments of the invention are explained in more detail below with reference to the figures as part of the description of a preferred embodiment of the invention. Wherein:

[0021] FIG. 1 shows a perspective view of an exemplary embodiment of a blower wheel according to the invention;

[0022] FIG. 2 shows the blower wheel from FIG. 1.

[0023] FIGS. 1 and 2 show a one-piece blower wheel 10 having a bottom disk 12 and a cover disk 11 between which a blade ring is formed having multiple blower wheel blades 13 disposed in the circumferential direction at a spacing from one another. The cover disk 11 comprises an axial intake opening 25 having a diameter di, which extends in a funnel-shaped curve when viewed in a radial section and forms an inlet nozzle at the intake opening 25. The outermost radial section of the cover disk 11 and the entire bottom disk 12 each extend parallel to an axial plane, that is, perpendicular to the axis of rotation of the blower wheel 1.

[0024] At its circumferential edge 14, which defines the intake opening 25, the cover disk 11 has a thickness t which corresponds to the thickness t of the blower wheel blades 13. The bottom disk 12 also has the thickness t on its radially outer edge 15 and is flush in a plane with an radially outer edge 18 of the blower wheel blades 13, which edge extends in a plane parallel to the axis of rotation of the blower wheel 1. The material thickness t of the bottom and cover disks 12, 11 is constant from radially inside to radially outside over their overall extension.

[0025] The bottom disk 12 extends radially inwards from the radially outer edges 18 of the blower wheel blades 13 and directly covers sections of the axial front sides of the blower wheel blades 13, wherein the bottom and cover disks, 12, 11 do not overlap in an axial top view, as viewed in a projection.

[0026] The size ratios of the blower wheel 1 are essential in fluidic respect and for solving the technological problem. The bottom disk 12 defines a maximum radial diameter da. The cover disk 11 extends radially outwards from the circumferential edge 14 which forms the intake opening 25 and has a maximum outer diameter dt. The ratio of the outer diameters dt/da is a preferred 0.74 in the exemplary embodiment shown. Furthermore, the di/dt ratio is at a value of 0.6. The maximum variation is .+-.0.3.

[0027] The cover disk 11 forms the part of the blower wheel 1 located radially inside on the intake side and covers sections of the blower wheel blades 13 in the area of the intake opening 25. The bottom disk 12 covers the blower wheel blades 13 in the area located radially outside. The blower wheel blades 13 extend in a straight line from the radially outer edge 19 of the cover disk 11, but inclined radially outwards in the circumferential direction. The axial front sides 17 of the blower wheel blades 13 have free ends and are uncovered on a side opposite the bottom disk 12.

[0028] The blower wheel 10 further comprises a hub 16 into which the blower wheel blades 13 transition on their radially inner sides, wherein the radially inner edges 20 of the blower wheel blades 13 are arc-shaped.

Claims

1. A blower wheel in a one-piece design having a bottom disk and a cover disk between which a blade ring is formed having multiple blower wheel blades disposed in the circumferential direction at a spacing from one another, wherein the bottom disk defines a maximum radial diameter da and the cover disk forms an axial intake opening having a diameter di, wherein the cover disk extends radially outwards from the circumferential edge which forms the intake opening and has a maximum outer diameter dt, and wherein an outer diameter ratio dt/da is defined in a range from 0.6 to 0.8.

2. The blower wheel according to claim 1, wherein the outer diameter ratio dt/da is set in a range from 0.66 to 0.77.

3. The blower wheel according to claim 1, wherein the outer diameter ratio dt/da is set to a value of 0.69 or 0.74 with a respective maximum variation of .+-.0.03.

4. The blower wheel according to claim 1, wherein the blower wheel blades start from the circumferential edge of the cover disk and extend radially outwards, and the axial front sides of the blower wheel blades are uncovered and extend radially outwards on a side opposite the bottom disk and comprise a free end each.

5. The blower wheel according to claim 1, wherein the cover disk, viewed in a radial section, is curved in a funnel-shaped manner and forms an inlet nozzle.

6. The blower wheel according to claim 1, wherein the cover disk has at its circumferential edge, which defines the intake opening, a thickness t which corresponds to the thickness t of the blower wheel blades.

7. The blower wheel according to claim 1, wherein the bottom disk, at least at its radially outer edge, has a thickness t that corresponds to the thickness t of the blower wheel blades.

8. The blower wheel according to claim 1, wherein a radial outer edge of the cover disk has the thickness t of the blower wheel blades.

9. The blower wheel according to claim 12, wherein the bottom and/or cover disk(s) have a constant material thickness t.

10. The blower wheel according to claim 1, wherein a ratio of the diameter of the axial intake opening di and the maximum outer diameter dt of the cover disk di/dt is in a range from 0.5 to 0.7.

11. The blower wheel according to claim 1, wherein radial inner edges of the blower wheel blades are arc-shaped.

12. The blower wheel according to claim 1, wherein it comprises a hub into which the blower wheel blades transition on their radially inner sides.

13. The blower wheel according to claim 1, wherein the outermost radial sections of the cover disk and the bottom disk extend parallel to an axial plane.

14. The blower wheel according to claim 1, wherein the bottom disk and the cover disk extend without overlapping relative to one another in an axial top view, as viewed in a projection.

15. A blower designed as a gas-air premix blower for delivering a gas-air mixture, including a multi-part blower housing and a motor unit with motor electronics disposed on its outer side, wherein a blower wheel according to claim 1 is disposed inside said blower housing which, when in operation, draws in air via an intake opening of the blower housing and blows out air via a blowout opening of the blower housing, wherein the motor unit includes a rotor which is in operative connection with the blower wheel.