DIAGONAL VENTILATOR WITH DOWNFLOW DEVICE

Description

[0001] The invention relates to a diagonal fan in a compact axial design and with a simultaneously high throw distance.

[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 mounted motor in diagonal fans, the discharge area at the outlet is comparatively small, resulting in high discharge losses due to the high dynamic pressure at the fan outlet.

[0004] The prior art in the present technical field is disclosed in documents EP 2 410 183 A2, EP 1 895 166 A1, DE 20 2016 106 538 U1 and EP 3 287 707 A1.

[0005] Axial fans are typically used to achieve long throw distances. However, diagonal fans are advantageous for compact design. The invention solves the problem of achieving both aspects of a compact design while simultaneously achieving a long throw distance and pressure increase.

[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 impeller during operation is deflected into an axial flow direction by an inner wall of the housing. Viewed in the axial flow direction, a guide vane assembly with a plurality of circumferentially distributed guide blades is arranged downstream of the diagonal impeller. This guide vane assembly homogenizes the airflow generated by the diagonal impeller, with the guide blades having a radial extension from a hub region of the guide vane assembly to the housing. The guide vane assembly is arranged at a specific axial distance from the diagonal impeller.For this purpose, a point is defined at which an imaginary extension in the outflow angle of the diagonal impeller intersects the inner wall of the housing at an axial distance K from the diagonal impeller. The guide vane is arranged axially in a region around the intersection of the outflow angle and the inner wall of the housing at an axial distance H from the diagonal impeller, where 0.75 ≤ K / H ≤ 1.25. The outflow angle of the diagonal impeller is determined via the impeller blades or an optional additional centrifugal ring. The measuring point on the guide vane is the foremost axial plane pointing towards the diagonal impeller, while on the diagonal impeller, the axial plane is defined by the radial outer edge of the impeller blades or, if a centrifugal ring is used, by its axial end pointing towards the guide vane.

[0008] The diagonal airflow expelled by the diagonal impeller is deflected axially by the housing and homogenized by the guide vane. This special arrangement enables a long throw range while maintaining a compact axial design.

[0009] 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.

[0010] According to the invention, the guide vane has a protective grille extending over the discharge section of the diagonal fan. The axial length L of the protective grille is less than 50% of the maximum axial length C of the guide vane.

[0011] 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.

[0012] According to the invention, the protective grid further comprises a plurality of coaxially arranged ring struts, each forming opposing strut surfaces running parallel to the axial flow direction. The flow thus proceeds in a guided, parallel manner along the strut surfaces over the entire axial length L of the protective grid.

[0013] In this design, the annular webs project axially towards the leading edge of the respective guide vanes. The guide vanes can thus be partially formed by the projecting section of the annular webs, resulting in an axially increased web area formed by the annular webs in the guide vane region. Furthermore, the axially projecting sections of the annular webs can serve to stiffen the guide vanes.

[0014] The guide vanes of the guide system can have different shapes and cross-sections. In an advantageous embodiment, the guide vanes are curved in an arc-like shape in axial cross-section and are additionally or alternatively profiled. The profiled shape can, for example, be an airfoil shape, i.e., a convexly curved shape. This allows for the different angles of attack of the respective diagonal impeller to be accommodated. A straight radial extension of the guide vanes is also possible.

[0015] In addition to the forward or backward curved design in axial cross-section, the guide vanes of the guidance device can also be designed in a further alternative three-dimensionally curved design, i.e. the curvature also takes place in axial extension.

[0016] A cost-effective design of the diagonal fan also provides that the guide vanes of the guide device transition directly into the protective grille and thus interact directly in terms of fluid dynamics.

[0017] In addition to the guide vane, the diagonal impeller also includes a hub with impeller blades attached to or formed on it. The two hubs or hub sections are preferably dimensioned such that the maximum diameter G of the hub section of the guide vane is larger than the maximum diameter F of a hub of the diagonal impeller, so that the hub section of the guide vane overlaps the hub of the diagonal impeller in axial projection.

[0018] A further advantageous solution for the axially compact design of the diagonal fan is characterized by the fact that the guide vane has a motor mount for the electric motor in the hub area. The hub area of ​​the guide vane can also be axially recessed for this purpose, so that the motor components and the guide vane overlap in radial section.

[0019] As mentioned above, an advantageous embodiment of the diagonal fan features a diagonal impeller with a centrifugal ring that surrounds impeller blades distributed circumferentially. The centrifugal ring allows for a precisely adjustable discharge angle and a flow path at a predetermined angle to the axis of rotation of the diagonal impeller.

[0020] Another advantageous aspect is the use of an external rotor motor for the diagonal fan. This allows the diagonal impeller to completely enclose the motor, minimizing the axial space requirement.

[0021] A further development of the diagonal fan provides that it includes an inlet nozzle which is arranged on the intake side of the housing. The inlet nozzle preferably extends axially into the centrifugal ring, so that the inlet nozzle and the centrifugal ring overlap section by section when viewed radially.

[0022] 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 perspective exploded view of a diagonal fan with a view of the inlet side, Fig. 2 a perspective exploded view of the diagonal fan made of Figure 1 with a view of the outlet side; Fig. 3 a radial section view of the diagonal fan from Figure 1 ; Fig. 4 a perspective sectional view of the diagonal fan made of Figure 1 .

[0023] In the Figures 1 to 4 Figure 1 shows an embodiment of a diagonal fan 1 according to the invention.

[0024] In the exploded views according to the Figure 1 and 2 The components of the housing 2 with the fixed guide vane 3 formed in one piece on it, the diagonal impeller 4, the electric motor 5 designed as an external rotor motor and the inlet nozzle 6 which can be inserted into the housing 2 can be identified.

[0025] In the Figures 3 to 4The diagonal fan 1 is shown in its assembled state and has a total axial length E. The diagonal impeller 4 comprises several impeller blades 9 extending radially outward from the axially open hub 8 and surrounded by the centrifugal ring 14. The centrifugal ring 14 has a flow cross-section that widens radially outward in the axial flow direction and is directed toward the inner wall of the housing 2. The electric motor 5 is inserted into the axially open hub 8 of the diagonal impeller 4 and is completely enclosed by it. In the axial direction, i.e., along the axis of rotation, the electric motor 5 extends into the axially central recess 11, allowing the latter to be positioned closer to the diagonal impeller 4. The diagonal impeller 4, driven by the electric motor 5, is arranged within the housing 2, which forms a flow channel, and has an axial length D.The inlet nozzle 6 is arranged on the inlet side and extends with its end section of the smallest flow cross-section (diameter A) into the area of ​​the diagonal impeller 4, so that the centrifugal ring 14 and the end section of the inlet nozzle 6 overlap.

[0026] In operation, the diagonal fan 1 draws in air axially via the diagonal impeller 4 and conveys it diagonally, i.e., relative to the axis of rotation, at a predetermined discharge angle towards the inner wall of the housing 2. In the illustrated embodiment, the discharge angle is primarily determined by the centrifugal ring 14. The imaginary extension V in the discharge angle of the diagonal impeller 4, determined by the centrifugal ring 14, strikes the inner wall of the housing 2 at point P at an axial distance K from the diagonal impeller 4. The axial plane at which the centrifugal ring 14 terminates serves as the measuring point for the distance K. In embodiments without a centrifugal ring 14, the measurement is taken at the axial plane defined by the radial outer edge of the fan blades 9, designated by the letter H'. At the inner wall of the housing 2, the flow is then deflected back into an axial flow direction and conveyed to the guide vane 3.

[0027] Viewed in the axial flow direction, the diagonal impeller 4 is followed at a distance H by the guide vane assembly 3 with a plurality of circumferentially distributed guide vanes 7. The ratio between the distances K / H is set to 0.8 in the illustrated embodiment.

[0028] The guide vane 3 further comprises an integral protective grid 17 with a plurality of coaxially arranged annular webs 13, each forming opposing web surfaces 19 running parallel to the axial flow direction. The axial length L of the protective grid 17 corresponds to half the axial length C of the guide vane 3. The maximum flow cross-section of the guide vane (diameter B) is located on the discharge side in the region of the annular webs 13. The guide vane 3 homogenizes the flow by means of the guide vanes 7 and the protective grid 17. The guide vanes 7 extend axially through the protective grid 13 and thus penetrate the annular webs 13 as a kind of arc-shaped radial web, as is well known in Figure 2 can be seen.

[0029] In Figure 1It is clearly visible that the ring webs 13 in the area of ​​the guide vanes 7 project axially to the leading edge of the respective guide vanes 7 in section 12, thus ensuring stiffening and support of the guide vanes 7. The guide vanes 7 are curved in an arc shape both in axial cross-section and in radial section according to Figure 3 Curved radially outwards, resulting in a three-dimensional overall curvature. Furthermore, the guide vanes 7 are curved in radial section according to Figure 3 The profile is formed according to a wing shape, whereby their respective thicknesses initially increase in the axial direction and then decrease again.

[0030] Referring to Figure 3 The ratio of the maximum diameter G of the hub area of ​​the guide device 3 and the maximum diameter F of the hub 8 of the diagonal wheel 4 is shown, where G>F.

Claims

1. A diagonal fan (1) comprising an electric motor (5), a housing (2), and a diagonal impeller (4) received within the housing (2) and driveable through the electric motor (5), the diagonal flow of which generated during operation is diverted in an axial flow direction by an inner wall of the housing (2), wherein, when viewed in the axial flow direction, an outlet guide vane device (3) having a plurality of circumferentially distributed guide vanes (7) is disposed directly downstream of the diagonal impeller (4), which smooths an air flow generated by the diagonal impeller (4), wherein the guide vanes (7) radially extend from a hub region of the outlet guide vane device (3) to the housing (2), and wherein a virtual extension meets the inner wall of the housing at an outflow angle of the diagonal impeller at an axial distance K from the diagonal impeller, and the outlet guide vane device is disposed at an axial distance H to the diagonal impeller such that 0.75<K / H<1.25, the diagonal fan being characterised in that the outlet guide vane device (3) has a protective grid (17) extending beyond an exhaust portion of the diagonal fan (1), which has an axial length L smaller than an axial length C of the outlet guide vane device (3), wherein L<0.5C, wherein the protective grid (17) has a plurality of annular flanges (13) disposed coaxially relative to one another, forming respective flange surfaces (19) extending parallel and opposite to the axial flow direction, and wherein the annular flanges (13) in the region of the guide vanes (7) are formed axially projecting from a leading edge of the respective guide vanes (7).

2. The diagonal fan according to claim 1, characterised in that the outlet guide vane device is integrally formed with the housing.

3. The diagonal fan (1) according to claim 1 or 2, characterised in that the outlet guide vane device (3), the housing (2), and the protective grid (17) are integrally formed.

4. The diagonal fan (1) according to any one of the preceding claims, characterised in that the guide vanes (7) of the outlet guide vane device (3), when viewed in the axial cross-section, are formed arcuately curved and / or profiled.

5. The diagonal fan (1) according to any one of the preceding claims, characterised in that the guide vanes (7) of the outlet guide vane device (3) are formed three-dimensionally curved.

6. The diagonal fan (1) according to any one of the preceding claims, characterised in that the guide vanes (7) of the outlet guide vane device (3) directly transition into the protective grid (17).

7. The diagonal fan (1) according to any one of the preceding claims, characterised in that a maximum diameter G of the hub region of the outlet guide vane device (3) is larger than a maximum diameter F of a hub (8) of the diagonal impeller (4), such that the hub region of the outlet guide vane device (3) covers the hub (8) of the diagonal impeller (4) when viewed in an axial projection.

8. The diagonal fan (1) according to any one of the preceding claims, characterised in that the outlet guide vane device (3) has a motor mount for the electric motor (5) in the hub region.

9. The diagonal fan (1) according to any one of the preceding claims, characterised in that the diagonal impeller (4) has a slinger ring (14) enclosing impeller blades (9) distributed circumferentially.

10. The diagonal fan (1) according to the preceding claim, characterised in that the slinger ring (14) defines the outlet angle of the diagonal impeller (4).

11. The diagonal fan (1) according to any one of the preceding claims, characterised in that the electric motor (5) is formed as an external rotor motor.

12. The diagonal fan (1) according to any one of the preceding claims, characterised in that it comprises an inlet nozzle (6) disposed on the housing (2) on the suction side, and wherein the inlet nozzle (6) extends in the axial direction into the slinger ring (14).