DIAGONAL VENTILATOR WITH SPIN REDUCTION ON THE DIAGONAL IMPERIAL

Description

[0001] The invention relates to a diagonal fan with a swirl reduction on the diagonal impeller.

[0002] Diagonal fans and their use are generally known from the prior art, for example from DE 10 2014 210 373 A1.

[0003] Diagonal fans are used in applications with high airflow requirements, higher back pressure, and limited installation space, for example in refrigeration technology or cooker hoods. Due to the relatively large motor diameter of the axially centrally arranged motor and the radial expansion of the hub, the discharge area at the outlet is comparatively small. This results in high discharge losses due to the high dynamic pressure at the outlet of the diagonal fan.

[0004] The prior art in the present technical field, which reflects the preamble of claim 1, is disclosed in document US 2010 / 111 667 A1.

[0005] Axial fans are typically used to achieve long throw distances. However, diagonal fans are advantageous for compact designs. The invention solves the problem of providing a diagonal fan that is improved in terms of efficiency and throw distance and can therefore be used in a wider range of applications.

[0006] This problem is solved by the combination of features according to claim 1.

[0007] According to the invention, a diagonal fan is proposed comprising an electric motor, a housing, and a diagonal impeller housed within the housing and driven by the electric motor. The diagonal flow generated by the diagonal impeller during operation is deflected by the housing into an axial flow direction. The diagonal impeller has impeller blades distributed circumferentially and a centrifugal ring that circumferentially surrounds the impeller blades. The diagonal fan further comprises an inlet nozzle on the intake side, through which a main flow of the diagonal fan is drawn in. In radial section, the inlet nozzle extends at least partially overlapping the centrifugal ring, thereby forming a nozzle gap with it.The housing also features a bypass channel that forms a flow connection from a pressure-side ambient area of ​​the diagonal fan to an inlet side of the nozzle gap. The bypass channel is designed to guide a swirl-free secondary flow to the inlet side of the nozzle gap during operation of the diagonal fan.

[0008] The invention solves the problem by introducing the swirl-free bypass flow into the nozzle gap via the bypass channel. When using the combination of inlet nozzle and centrifugal ring, a gap flow is generated in the nozzle gap, which leads to improved flow contact with the centrifugal ring. In diagonal fans with channel-like, especially cylindrical, housings, this gap flow is primarily fed by the highly turbulent and swirling flow at the outlet (pressure side) of the diagonal impeller. The turbulent gap flow causes increased noise generation when it interacts with the leading edges of the impeller blades on the inlet side. Due to the swirl in the gap flow, the inflow vector to the diagonal impeller changes significantly within the shear layer between the gap flow and the main flow, resulting in an incorrect flow direction towards the impeller blades, i.e., an inflow at a suboptimal angle.The respective angle difference of the inflow vector is dependent on the operating point and cannot be geometrically compensated for at the fan blades. By introducing the swirl-free bypass flow into the intake nozzle via the bypass channel, the gap flow is influenced in such a way that noise generation is minimized and the efficiency of the diagonal fan is increased.

[0009] According to the invention, the bypass channel runs parallel to an outer shell wall of the housing and defines an inner wall of the housing, which deflects the diagonal flow generated by the diagonal impeller into the axial flow direction. The bypass channel is thus integrated into the housing in a space-saving manner.

[0010] From a fluid dynamics perspective, a diagonal fan design is advantageous in which the bypass channel has an axial flow cross-sectional area AB that has a ratio to the axial flow cross-sectional area AS of the nozzle gap such that 0.5 ≤ AB / AS ≤ 5. Preferably, the ratio is chosen such that 0.75 ≤ AB / AS ≤ 2.5. In the aforementioned ranges, the influence of the swirl-free bypass flow is particularly effective.

[0011] Furthermore, in one embodiment, the bypass channel radially surrounds the diagonal impeller on its outer side and is therefore arranged at the same axial height as the diagonal impeller. Instead of a completely surrounding channel, for example, two or four channels can also be arranged in the corners to better utilize the installation space.

[0012] The bypass channel is preferably designed with an axial length such that it extends the diagonal impeller axially on both sides, i.e., in radial section, it extends beyond the axial edge planes of the diagonal impeller on both sides. It is particularly advantageous if the inlet of the bypass channel on the pressure side is separate from the discharge area of ​​the main flow and is connected to the surroundings of the diagonal fan.

[0013] To reduce the number of parts and simplify assembly, it is preferable to form the bypass channel as a single piece on the housing.

[0014] Furthermore, from a fluid dynamics perspective, it is advantageous that, in the diagonal fan, the centrifugal ring and the inlet nozzle run parallel at least partially in the area of ​​the nozzle gap. In particular, it is preferred that the centrifugal ring runs coaxially radially outside the inlet nozzle, so that the nozzle gap is formed radially outside the inlet nozzle.

[0015] In a further development of the diagonal fan, the centrifugal ring in the nozzle section extends parallel to a rotation axis of the diagonal impeller extending in the axial direction of the diagonal fan, i.e. in the overlap section the centrifugal ring and the inlet nozzle run parallel to the axially drawn-in flow direction.

[0016] To generate an outflow obliquely radially outwards and at an angle to the rotation axis of the diagonal impeller, the centrifugal ring has a flow cross-section that widens radially outwards in the axial flow direction and is directed towards an inner wall of the housing.

[0017] In a further embodiment of the diagonal fan, viewed in the axial flow direction, a guide vane with a plurality of circumferentially distributed guide vanes is arranged downstream of the diagonal impeller, which homogenizes the airflow generated by the diagonal impeller.

[0018] An advantageous design of the diagonal fan involves integrating the guide vane with the housing. This reduces the number of parts and assembly steps. Furthermore, a seal between the components is no longer necessary.

[0019] In a further development, the guidance device features a protective grille that extends over the discharge section of the diagonal fan.

[0020] Another advantageous design variant of the diagonal fan is one in which the guide vane, the housing and the protective grille are formed in one piece.

[0021] For variable mounting of the diagonal fan at at least two mounting points, the housing is provided with at least two axial screw-on surfaces, each equipped with fasteners for attaching the diagonal fan. The diagonal fan is mounted, for example, to a heat exchanger.

[0022] Furthermore, a further development of the diagonal fan with regard to a compact design is advantageous, in which the guide vane in the hub area has a motor mount for the electric motor. The mounting of the electric motor can thus be handled by the guide vane.

[0023] Other advantageous embodiments of the invention are characterized in the dependent claims or are described in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. The figures show: Fig. 1 a schematic radial section view of an embodiment of a diagonal fan.

[0024] In Figure 1Figure 1 is an exemplary embodiment of a diagonal fan 1, shown schematically in radial section. The diagonal fan 1 comprises a housing 11 in which the electric motor 10, designed as an external rotor motor, is housed and connected to the diagonal impeller 12 to rotate the latter about the axis of rotation RA during operation. The diagonal impeller 12 is attached to the electric motor 10 by its hub 119. Several impeller blades 121, distributed circumferentially, extend radially outwards from the hub 119, their radially outer ends being closed by the centrifugal ring 122. The fan blades 121 have a leading edge 117 and a trailing edge 118, which are each inclined relative to a vertical perpendicular to the axis of rotation from radially inside to radially outside towards the inlet side of the diagonal fan 1, the angle at the trailing edge 118 being greater than at the leading edge 117.

[0025] On the intake side, an inlet nozzle 6, integrally formed with the housing 11, is provided through which the diagonal impeller 12 draws in the main flow HS during operation. The inlet nozzle 6 has a flow cross-section that decreases in the axial direction, being smallest at the axially free end section 7. This free end section 7 runs parallel to the axis of rotation RA and overlaps in the overlap area 30 with the front section 123 of the centrifugal ring 122, which also extends parallel to the axis of rotation RA. The centrifugal ring 122 and the inlet nozzle 6 form the nozzle gap 19. The axially parallel front section 123 of the centrifugal ring 122 is immediately joined by the rear section 124, which runs obliquely outwards and at an angle to the axis of rotation and determines the flow cross-section which widens radially outwards in the axial flow direction and is directed towards an inner wall 111 of the housing 11.

[0026] The bypass channel 22 is integrally formed on the housing 11. It extends axially from the discharge section 27 of the diagonal fan 1 to the inlet nozzle 6 and forms a flow connection from the pressure-side ambient area U of the diagonal fan 1, via the axial inlet opening 21, to the inlet side of the nozzle gap 19. During operation, in addition to the main flow, a swirl-free secondary flow NS is generated in the bypass channel 22, flowing in the opposite direction, and fed to the main flow HS via the nozzle gap 19. The bypass channel 22 extends axially beyond the entire diagonal impeller 12 and is integrally arranged radially outside the impeller on the housing 11. The bypass channel 22 has an axial flow cross-sectional area AB, which in relation to an axial flow cross-sectional area AS of the nozzle gap 19 in the embodiment shown is such that AB / AS=3.0.The ratio is preferably set in a range of 0.5-5.0.

[0027] Furthermore, the diagonal fan 1 includes a guide vane 90 at the discharge section 27, which subsequently homogenizes the diagonal flow discharged at an angle by the diagonal impeller 12 and the flow deflected back into the axial direction by the inner wall 11. The guide vane 90 comprises a plurality of circumferentially distributed guide vanes and a protective grille, which then extends the discharge section 27 of the diagonal fan 1.

Claims

1. A diagonal fan (1) comprising an electric motor (10), a housing (11), and a diagonal impeller (12), which is received inside the housing (11) and is drivable via the electric motor (10) and of which diagonal impeller (12) generated in operation is deflected in an axial flow direction, wherein the diagonal impeller (12) includes impeller blades (121) distributed in the circumferential direction and a slinger ring (122), which encloses the impeller blades (121) in the circumferential direction, wherein the diagonal fan (1) furthermore includes an inlet nozzle (6) on the suction side, through which a main flow (HS) of the diagonal fan (1) is suctioned in, wherein the inlet nozzle (6) extends overlapping at least in sections in relation to the slinger ring (122) viewed in radial section and forms a nozzle gap (19) with the slinger ring (122) at the same time, and wherein a bypass channel (22) is formed on the housing (11), which forms a flow connection from a pressure-side surrounding region (U) of the diagonal fan (1) to an inflow side of the nozzle gap (19), wherein the bypass channel (22) is formed to guide, in operation of the diagonal fan (1), a swirl-free secondary flow (NS) at the inflow side of the nozzle gap (19), characterized in that the bypass channel (22) extends in parallel to an outer jacket wall of the housing (11) and defines an inner wall (111) of the housing (11), which deflects the diagonal flow generated by the diagonal impeller (12) in the axial flow direction.

2. The diagonal fan as claimed in claim 1, wherein the bypass channel (22) has an axial through-flow cross-sectional area (AB), which has a ratio to an axial through-flow cross-sectional area AS of the nozzle gap (19) such that 0.5≤ AB / AS ≤ 5, in particular 0.75≤ AB / AS ≤ 2.5.

3. The diagonal fan as claimed in any one of the preceding claims 1 or 2, wherein the bypass channel (22) encloses the diagonal impeller (12) on the radial outside at least in regions.

4. The diagonal fan as claimed in any one of the preceding claims, wherein the bypass channel (22) extends beyond the diagonal impeller (12) on both sides in the axial direction.

5. The diagonal fan as claimed in any one of the preceding claims, wherein the bypass channel (22) is integrally formed on the housing (11).

6. The diagonal fan as claimed in any one of the preceding claims, wherein wherein the slinger ring (122) and the inlet nozzle (6) extend in parallel at least in sections in the region of the nozzle gap (19).

7. The diagonal fan as claimed in any one of the preceding claims, wherein the slinger ring (122) extends coaxially radially outside the inlet nozzle (6).

8. The diagonal fan as claimed in any one of the preceding claims, wherein the slinger ring (122) extends in the region of the nozzle gap (19) in parallel to a rotational axis of the diagonal impeller (12) extending in the axial direction of the diagonal fan (1).

9. The diagonal fan as claimed in any one of the preceding claims, wherein the slinger ring (122) has a flow cross section widening radially outward in the axial flow direction and oriented toward an inner wall (111) of the housing (11).

10. The diagonal fan as claimed in any one of the preceding claims, characterized in that a redirection device (90) having a plurality of guide blades distributed in the circumferential direction, which evens out an airflow generated by the diagonal impeller (12), is arranged adjoining the diagonal impeller (12) viewed in the axial flow direction.

11. The diagonal fan as claimed in any one of the preceding claims, characterized in that the redirection device (90) includes a protective grating extending over a discharge section (27) of the diagonal fan (1).

12. The diagonal fan as claimed in any one of the preceding claims, characterized in that at least two axial screw-on planes each having fastening means for fastening the diagonal fan (1) are formed on the housing (11).

13. The diagonal fan as claimed in any one of preceding claims 10-12, characterized in that the redirection device (90) includes a motor receptacle for the electric motor (10) in the hub region.