Flow guiding element for a radial, axial or diagonal fan, and radial or diagonal fan with flow guiding element

Abstract

The invention relates to a flow guide element (27) and a radial, axial, or diagonal fan with such a flow guide element (27). The flow guide element (27) has a flow section (29) and a termination section (30). The termination section (30) interacts with a section of the rotor (16) of the radial, axial, or diagonal fan, which is located immediately adjacent to a downstream end section (28) of a flow channel (31) bounded by the flow section (29). This section can, for example, be formed by a centrifugal ring (22) of the rotor (16). The material of this section of the rotor (16) (e.g., centrifugal ring (22)) has a greater hardness than the material of the termination section (30) of the flow guide element (27). Additionally or alternatively, the hardness of the flow section (29) can be greater than the hardness of the termination section (30).

Description

[0001] The invention relates to a flow guide element for a radial, axial or diagonal fan and to a radial, axial or diagonal fan comprising a flow guide element.

[0002] A radial fan with a flow guide element is known, for example, from DE 42 18 826 A1. The flow guide element is designed to direct an inlet flow on the suction side of the radial fan to the rotor of the radial fan. The rotor is arranged at a distance from the flow guide element. This allows the rotor to rotate without friction relative to the flow guide element.

[0003] JP 2014-227891 A describes a radial fan with an intake cone and a rotor. Adjacent to the rotor, at the free end of the intake cone, an element is arranged to maintain a defined gap between the rotor and the intake cone. This element consists of a non-metallic material with a low coefficient of friction, for example, Teflon or a non-asbestos-containing sealing material.

[0004] JP S57 120 798 U relates to a fan with a rotor and a housing cone, between which there is a gap. A ring is arranged on the housing cone to adjust the gap width.

[0005] A radial fan is known from CN 105 697 409 A, in which leakage losses are to be minimized. For this purpose, it has a sealing component on the fan housing that is in contact with a rotor. A gap present there can be in the range of 0.2 to 1 millimeter and results from the fan's break-in period.

[0006] US 2006 / 051205 A1 discloses a blower with an electric motor and a housing cover having an inlet opening limited by a hollow cylindrical lip. The lip is an integral part of the housing cover, which can be made of metal or plastic by injection molding.

[0007] Starting from the prior art, the object of the present invention is to create a flow guide element that enables improved efficiency of the operation of a radial, axial or diagonal fan.

[0008] This problem is solved by a flow guide element with the features of claim 1 and by a radial, axial or diagonal fan with the features of claim 6.

[0009] The flow guide element according to the invention has a flow section and a termination section made of materials with different hardness. Preferably, the flow guide element consists of these two parts. The flow section and the termination section can be joined together during and through the manufacture of the flow guide element, for example, by a two-component casting process, in particular an injection molding process. In this process, the flow section and the termination section can be manufactured and joined together. Alternatively, it is also possible to first manufacture the flow section or the termination section and place it in a mold. Subsequently, the other part is manufactured by a casting process and thereby joined to the flow section or the termination section.It is also possible, according to an embodiment that does not belong to the claimed invention, to manufacture the flow part and the end part separately and then to connect them together by means of an adhesive bond or a material-bonded connection.

[0010] In another embodiment, which is not part of the claimed invention, the flow part and the end part are made of the same material.

[0011] The flow element surrounds a flow channel. In one embodiment, the flow element alone can define the flow channel, or alternatively, the flow element and the end piece together can define the flow channel. The end piece is arranged at one end section of the flow element. The end piece is designed to provide a finishing edge or surface for a rotor, and in particular a centrifugal ring of the rotor of the radial, axial, or diagonal fan, against which the rotor of the radial, axial, or diagonal fan can abut or be positioned with a small gap. The end piece is made of a material whose hardness is less than that of the rotor material of the radial or diagonal fan.In a design where the flow section is made of a different material than the end section, the hardness of the material of the end section can be lower than the hardness of the material of the flow section.

[0012] The softer end cap allows the rotor of the radial, axial, or diagonal fan to be in lubricating contact with the end cap during initial startup and to wear into the end cap during the first operating phase. Alternatively, the gap between the rotor and the end cap can be very small during startup, for example, a maximum of 1.0 mm or 0.5 mm. In particular, the ratio of the gap to the intake diameter of the radial, axial, or diagonal fan can be in the range of 0 to 0.01 inclusive. For radial fans, the ratio of the gap to the intake diameter is preferably in the range of 0 to 0.006 inclusive.Changes in the gap width due to temperature fluctuations, which lead to – at least temporarily – abrasive contact between the rotor and the end piece, are not problematic due to the end piece's lower hardness material. In both cases, unwanted leakage flow between the flow guide element and the rotor can be reduced or, ideally, prevented. While the efficiency may be slightly lower at times due to the abrasive contact between the rotor and the end piece, the rotor can wear into the softer material of the end piece during operation. After this wear-in period, there is only minimal or no frictional resistance, and the smaller gap width results in improved efficiency compared to previous fan designs.

[0013] In one embodiment, the flow section of the flow element can be made of a metallic alloy or of plastic.

[0014] Preferably, at least the end part is made of plastic, in particular of an elastic plastic such as an elastomer or a thermoplastic elastomer. Materials containing rubber, preferably synthetic rubber, can also be used.

[0015] It is advantageous if the end piece is made of a material having a hardness of no more than 80 or 90 Shore D or 80 or 90 Shore A. Preferably, the hardness is determined according to DIN EN ISO 868 or DIN ISO 7619-1 or ASTM D2240-00.

[0016] The radial, axial, or diagonal fan according to the invention preferably has a centrifugal ring and a motor and a rotor that is rotatably mounted about an axis of rotation. The rotor can be driven by the motor. Fan blades are arranged on the rotor, which generate a gas flow when the rotor rotates about the axis of rotation.

[0017] A flow element is arranged upstream of the rotor. The flow element can be designed according to one of the embodiments described above.

[0018] The flow guide element of the radial, axial, or diagonal fan according to the invention has a flow section and a closing section. The closing section is arranged directly adjacent to the rotor. The closing section is made of a material that has a lower hardness than the material of the entire rotor or at least of the section of the rotor that is adjacent to the closing section.

[0019] As explained above, this allows for the establishment of a sliding contact between the rotor and the end piece, or a very small gap between the rotor and the end piece, during commissioning. This leads to improved operating efficiency of the radial, axial, or diagonal fan.

[0020] According to the invention, the end piece is made of a material with a lower hardness than the material of the flow section. The material of the flow section can be selected independently of the end piece according to other required properties, irrespective of hardness, such as weight, manufacturing costs, thermal expansion, etc.

[0021] At least during initial commissioning, the end cap can rest against the rotor, allowing the rotor to essentially wear into the end cap as it rotates around its axis. Alternatively, a gap can be set between the end cap and the rotor during commissioning, for example, a small gap width of no more than 1.0 mm or 0.5 mm. Preferably, the ratio of the gap width to the intake diameter of the radial, axial, or diagonal fan is in the range of 0 to 0.01 inclusive.

[0022] The gap width can be measured perpendicular to the flow direction through the gap. The gap width can therefore be defined by the distance between the rotor and the end piece in a cross-sectional plane through the gap.

[0023] In one embodiment, the end piece can abut a leading edge or a front surface of the rotor. The leading surface or leading edge is essentially oriented in an axial direction parallel to the axis of rotation. The leading edge or front surface can, for example, be planar or have a convex curve. The leading edge or front surface connects, in particular, an inner surface facing the axis of rotation with an outer surface facing away from the axis of rotation. The inner surface and the outer surface can, for example, be arranged concentrically to each other.

[0024] In another embodiment, the end piece can rest against an inner edge or an inner surface of the rotor. The inner edge or the inner surface can face the axis of rotation of the rotor.

[0025] In another modified embodiment, it is also possible for the end part to rest against an outer edge or an outer surface of the rotor that faces away from the axis of rotation.

[0026] The radial, axial, or diagonal fan can be, for example, a backward-curved radial fan, an axial fan, or a diagonal fan with a centrifugal ring. In a backward-curved radial fan, the fan blades of the rotor curve radially outward from an inner edge to an outer edge, relative to a radial plane that contains the axis of rotation. The curvature is directed opposite to the direction of rotation of the rotor. The outer edge can be positioned behind the inner edge of the fan blade in the direction of rotation.

[0027] Advantageous embodiments of the invention will become apparent from the dependent claims, the description, and the drawings. Preferred embodiments of the invention are explained in detail below with reference to the accompanying drawings. The drawings show: Figure 1 a schematic sectional view of an embodiment of a radial, axial or diagonal fan according to the invention with a flow guide element in a schematic sectional view along the axis of rotation of the radial, axial or diagonal fan, Figure 2-8 Each is an exemplary embodiment of a design of a transition area between the flow guide element and the rotor of the radial, axial or diagonal fan in a partial representation (area X in Figure 1 ), Figure 9a schematic representation of the overall efficiency of the radial, axial or diagonal fan according to the invention compared with a radial fan according to the prior art, each depending on the volume flow rate, Figure 10 a schematic representation of the pressure on the suction side of the radial, axial or diagonal fan according to the invention compared with a radial fan according to the prior art, each depending on the volume flow rate and Figure 1 A schematic representation of the noise development of the radial, axial or diagonal fan according to the invention compared with a radial fan according to the prior art, each depending on the volume flow rate.

[0028] The invention is suitable for use in or with a radial, axial, or diagonal fan. The invention is explained below based on an exemplary embodiment in connection with a radial fan 15 and can, for example, also be used with a diagonal fan with a centrifugal ring.

[0029] In Figure 1 Figure 15 schematically illustrates an embodiment of the radial fan 15 in a cross-sectional view along an axis of rotation R. The radial fan 15 has a rotor 16 rotatably mounted about the axis of rotation R. The rotor 16 can be driven to rotate about the axis of rotation R by a motor 17.

[0030] The rotor 16 has a back side 18 and a front side 19. On the back side 18, the rotor 16 has a connecting element 20 that is rotationally fixed to the rotor of the motor 17. The connecting element 20 can, for example, be a connecting ring 21.

[0031] In an axial direction A parallel to the axis of rotation R, the rotor 16 has a centrifugal ring 22, spaced apart from the connecting ring 21, which coaxially surrounds the axis of rotation R. Between the connecting ring 21 and the centrifugal ring 22, several fan blades 23 extend, distributed circumferentially around the axis of rotation R. The shape and size of the fan blades 23 can vary. In this embodiment, it is a backward-curved radial fan 15. The fan blades 23 extend in a curved path around the axis of rotation R in the direction of rotation of the rotor 16. Each fan blade 23 has an inner edge located radially inside and an outer edge located radially outside with respect to the axis of rotation R. In the direction of rotation around the axis of rotation R of the rotor 16, the outer edge can be located further back than the inner edge of each fan blade 23. The inner edges of the fan blades 23 are arranged at a distance from the axis of rotation R.

[0032] Upstream of the rotor 16 in the flow direction, the radial fan 15 has a flow guide element 27. The flow guide element 27 is designed to direct the inlet flow of the radial fan towards the rotor 16. The minimum inner diameter of the flow guide element 27 corresponds, for example, to an intake diameter d. In the radial fan 15, the intake flow is directed radially within the fan blades 23 and, when the rotor 16 rotates, is discharged tangentially to the direction of rotation of the rotor 16 into an outlet channel (not shown) of a housing.

[0033] The flow guide element 27 has a downstream end section 28, which is associated with the rotor 16 of the radial fan 15. The rotor 16 is located adjacent to the end section 28. The transition area between the end section 28 of the flow guide element 27 and the rotor 16 is Figure 1 marked with X and schematically shown for different embodiments in the Figure 2-8 depicted.

[0034] According to the invention, the flow guide element 27 has a flow section 29 and a closing section 30. At least the flow section 29 defines a flow channel 31 through which the intake flow can pass. In some embodiments of the flow guide element 27, the flow channel 31 can also be jointly defined by the flow section 29 and the closing section 30.

[0035] The flow section 29 and the end section 30 are made of different materials. According to the invention, the hardness of the material of the end section 30 is lower than the hardness of the material of the flow section 29. The flow section 29 can, for example, be made of a metallic alloy or plastic. Preferably, the end section 30 is made of plastic, and in particular of an elastic plastic, such as an elastomer or a thermoplastic elastomer.

[0036] The end piece 30 preferably has a hardness of no more than 80 to 90 Shore D or 80 to 90 Shore A. The hardness can be determined according to DIN EN ISO 868 or DIN ISO 7619-1 or ASTM D2240-00.

[0037] The hardness of the material of the rotor 16, or at least of the centrifugal ring 22, is greater than the hardness of the material of the end piece 30. This makes it possible to position the rotor 16 and, for example, the centrifugal ring 22 in contact with the end piece 30 when the radial fan 15 is put on, so that the rotor 16 or the centrifugal ring 22 wears into the end piece 30 during the first operating phase of the radial fan 15. During this wearing process, material is removed from the end piece 30, and the end surface in contact with the rotor adapts to the contour of the contact surface of the rotor 16. This wearing process reduces the frictional resistance during rotation of the rotor 16 relative to the end piece until there is no frictional resistance or only a very low one. The gap between the rotor 16 and the end piece 30 can thus be almost completely eliminated.

[0038] Alternatively, the rotor 16 can be installed relative to the end piece 30 such that the gap width w of a gap 32 between the rotor 16 (for example, the centrifugal ring 22) and the end piece 30 is, for example, a maximum of 1.0 mm and preferably a maximum of 0.5 mm. In the exemplary embodiment, the ratio of the gap width w to the intake diameter d is: 0 ≤ w / d ≤ 0.01, in particular 0 ≤ w / d ≤ 0.0006. An exemplary embodiment with a gap 32 between the end piece 30 and the centrifugal ring 22 is shown in Figure 3 depicted.

[0039] In other embodiments or other fan types, in particular axial or diagonal fans, the following may apply to the ratio of the gap width w to an intake diameter d, for example: 0 ≤ w / d ≤ 0.01.

[0040] The centrifugal ring 22 and preferably the entire rotor 16 can be made of a metallic alloy, a plastic, a composite material or a combination thereof.

[0041] The shape of the centrifugal ring 22 can vary depending on the design of the rotor 16 or the radial fan 15. In the exemplary embodiment, the centrifugal ring 22 is a three-dimensional body that is not merely plate-shaped and extends radially R and axially A with respect to the axis of rotation R. The centrifugal ring 22 has a front surface 35 on the front face 19 of the rotor, which can also be referred to as the leading edge. The front surface 35 connects an inner surface 36 of the centrifugal ring 22 facing the axis of rotation R with an outer surface 37 of the centrifugal ring 22 facing away from the axis of rotation R. Adjoining the front surface 35, the inner surface 36 in the exemplary embodiment has a front section 38 that extends substantially in the axial direction A. Additionally or alternatively, the outer surface 37 can have a front section 39 adjoining the front surface 35 that extends substantially in the axial direction A.Basically, the course of the inner surface 36 and the outer surface 37 can be chosen as desired, depending on the application.

[0042] In the embodiment of the centrifugal ring 22 illustrated here, the front surface 35 has a convexly curved profile and can, for example, be formed by a leading edge with a radius. Alternatively, the front surface 35 can also be a planar surface.

[0043] In the embodiment of the flow guide element 27 in Figure 2The end section 30 rests against the front surface 35. In the radial direction R, the width of the end section 30 can essentially correspond to the width of the adjoining flow section 29 and / or the front surface 35. The front surface 35 has worn into the end section 30, forming a concave recess. In this arrangement, the transition between the flow guide element 27 and the rotor 16 is essentially gap-free. Leakage flows between the flow guide element 27 and the rotor 16, and specifically between the end section 30 and the centrifugal ring 22, can be completely or almost completely avoided.

[0044] The exemplary embodiment according to Figure 3 essentially corresponds to the embodiment shown in Figure 2The difference lies in the fact that a gap 32 is present between the flow guide element 27 and the rotor 16, in particular between the end part 30 and the centrifugal ring 22. The gap width w is measured perpendicular to the flow direction through the gap 32 and, for example, perpendicular to the front surface 35. The gap width w can be chosen to be very small, preferably a maximum of 0.5 mm. In a variation of the illustrated embodiment, the surfaces bounding the gap 32 can also have any other shape and, for example, be planar surfaces extending perpendicular or obliquely to the axis of rotation R.

[0045] In Figure 4Figure 1 shows a modified embodiment of the flow guide element 27. The flow guide element 27 has a diameter in its end section 28 that is at most equal to the inner diameter of the front section 38 of the inner surface 36. In this embodiment, the end section 30 of the flow guide element 27 rests against the front section 38 of the inner surface 36 or, alternatively, can be arranged opposite the front section 38 of the inner surface 36, forming a gap. The end section 30 rests against the inner surface 36 at a point that is spaced apart from the front surface 35.

[0046] In a variation of this, it shows Figure 5An embodiment in which the end part 30 of the flow guide element 27 has an outer diameter which, at least after grinding, corresponds at most to the inner diameter of the inner surface 36 or the front section 38 of the inner surface 36. In the axial direction A, the end part 30 rests against the centrifugal ring 22 along a surface extending in the axial direction A, which is longer in the axial direction A than in the embodiment according to Figure 4 In this embodiment, the contact surface extends to the transition of the front section 38 of the inner surface 36 into the front surface 35. With this embodiment, a very good seal and simultaneously a good flow pattern can be achieved in the transition area between the flow guide element 27 and the rotor 16.

[0047] According to the invention, the end section 30 forms an extension of the flow section 29 in the end section 28 and connects to the flow section 29 in the direction of flow. Alternatively, according to an embodiment not part of the claimed invention, it is also possible for the end section 30 to form a layer or layer applied to the flow section 29 in the end section 28, as shown in a highly schematic way in the Figure 6 and 7 is shown. The final part 30 can be an outer layer 40 ( Figure 6 ) or an inner position 41 ( Figure 7 The outer layer 40 is located on the side of the flow section 29 facing away from the axis of rotation R and thus outside the flow channel 31. The inner layer 41 is located inside the flow channel 31, on the side of the flow section 29 facing the axis of rotation R.

[0048] The embodiments described above can also be combined with one another. For example, the end part 30 can cooperate with and abut the front surface 35 and the inner surface 36 and optionally also the outer surface 37, or be positioned opposite them, forming the gap 32.

[0049] Thus, for example, the embodiment can be implemented according to Figure 5 with the embodiment according to Figure 3 can be combined and thereby form an embodiment according to Figure 8 to be obtained. However, in the exemplary embodiment according to Figure 8 in contrast to the embodiment according to Figure 5 There is no connection between the end part 30 and the centrifugal ring 22. Rather, there is a gap, similar to the embodiment shown in [reference]. Figure 3 The gap 32 has a gap width w and is different from the embodiment shown in the diagram. Figure 3Not an axial gap, but a radial gap. In the exemplary embodiment, the gap 32 is as follows: Figure 8 formed between the final part 30 and the front section 38.

[0050] In the Figure 9-11 Curves K1 to K6 are schematically illustrated, each depending on the volume flow rate Q of the radial fan 15. Curves K1, K3, and K5 correspond to an embodiment of the radial fan 15 according to the present invention, wherein the centrifugal ring 22 rests against the end part 30 with essentially no gap. Curves K2, K4, and K6, shown with dashed lines, belong to a radial fan according to the prior art, which has a gap of approximately 3.0 mm between the rotor and the flow guide element.

[0051] Figure 9Figure 1 shows a first curve K1, which represents the overall static efficiency of the radial fan 15 according to the invention. A second curve K2, shown as a dashed line, represents the overall efficiency of the radial fan according to the prior art. The overall efficiency can be improved by approximately 4% to 5% by an embodiment according to the invention.

[0052] In Figure 10 In a third curve K3 and a fourth curve K4, the differential pressure p between the suction and pressure sides of the radial fan is shown as a function of the volume flow rate Q. The third curve K3 shows the differential pressure profile of the embodiment of the radial fan according to the invention, and the fourth curve K4 shows a radial fan according to the prior art.

[0053] Figure 11Figure 5 schematically shows the noise development of the inventive embodiment of the radial fan (fifth curve K5) and of the radial fan according to the prior art (sixth curve K6), where a sound power L is shown as a function of the volume flow Q. It can be seen that the sound power in the inventive embodiment is significantly lower than in the prior art, for example by up to 1.6 dBA.

[0054] Based on the Figure 9-11 It can be seen that the inventive design of the flow guide element 27 or of the radial fan 15 with such a flow guide element 27 brings significant advantages, not only with regard to efficiency.

[0055] The invention relates to a flow guide element 27 and a radial, axial, or diagonal fan with such a flow guide element 27. The flow guide element 27 has a flow section 29 and a termination section 30. The termination section 30 interacts with a section of the rotor 16 of the radial, axial, or diagonal fan, which is arranged immediately adjacent to a downstream end section 28 of a flow channel 31 bounded by the flow section 29. This section can, for example, be formed by a centrifugal ring 22 of the rotor 16. The material of this section of the rotor 16 (e.g., centrifugal ring 22) has a greater hardness than the material of the termination section 30 of the flow guide element 27. Reference symbol list:

[0056] 15 Radial fan 16 Rotor of the radial fan 17 Motor 18 Back of the rotor 19 Front of the rotor 20 Connecting element 21 Connecting ring 22 Centrifugal ring 23 Fan blade 27 Flow guide element 28 End section 29 Flow section 30 Termination section 31 Flow channel 32 Gap 35 Front surface 36 Inner surface 37 Outer surface 38 Front section of the inner surface 39 Front section of the outer surface 40 Outer position 41 Inner position Axial direction d Intake diameter G Overall efficiency K1 First curve K2 Second curve K3 Third curve K4 Fourth curve K5 Fifth curve K6 Sixth curve L Sound power p Inlet pressure Q Volume flow R Axis of rotation w Gap width

Claims

1. Flow guide element (27) for flow guidance of a suction flow for a radial, axial or mixed flow fan (15), wherein the flow guide element (27) comprises a flow part (29) and an end part (30), wherein the flow part (29) surrounds a flow channel (31) at the downstream arranged end section (28) of which the end part (30) is arranged consisting of a material having a lower hardness than the material of flow part (29), characterized in that the flow part (29) and / or the end part (30) are produced by a molding process and the flow part (29) and the end part (30) are connected with each other due to the production, and that the end part (30) forms an extension of the flow part (29) in the end section (28) and adjoins the flow part (29) in flow direction.

2. Flow guide element according to claim 1, wherein the flow part (29) consists of a metallic alloy or a plastic.

3. Flow guide element according to claim 1 or 2, wherein the end part (30) consists of plastic.

4. Flow guide element according to any of the preceding claims, wherein the end part (30) consists of a material containing an elastomer, particularly a thermoplastic elastomer.

5. Flow guide element according to any of the preceding claims, wherein the end part (30) consists of a material having a hardness of maximum 80 or 90 Shore-A or Shore-D.

6. Radial, axial or mixed flow fan (15) comprising: - a motor (17), - a rotor (16) that can be driven by the motor (17), wherein fan blades (23) are arranged on the rotor (16), which are configured to produce a gas flow upon rotation of the rotor (16) around a rotation axis (R), - a flow guide element (27) according to any of the preceding claims, that is arranged upstream the rotor (16), wherein the end part (30) is arranged directly adjacent to the rotor (16) and consists of a material having a lower hardness than the material of the section of the rotor (16) that is arranged directly adjacent to the end part (30).

7. Radial, axial or mixed flow fan according to claim 6, wherein the end part (30) is at least in sections in contact with the rotor (16).

8. Radial, axial or mixed flow fan according to claim 6, wherein the end part (30) and the rotor (16) limit a gap (32) having a gap width (w), wherein the ratio of the gap width (w) divided through a suction diameter (d) of the radial or mixed flow fan is lower than 0.01.

9. Radial, axial or mixed flow fan according to any of the preceding claims, wherein the end part (30) is in contact with the front surface (35) of the rotor (16), which is substantially orientated parallel to the rotation axis (R).

10. Radial, axial or mixed flow fan according to any of the claims 1 to 8, wherein the end part (30) is in contact with an inner surface (36) of the rotor (16) that faces the rotation axis (R).

11. Radial, axial or mixed flow fan according to any of the claims 6 to 10, wherein the radial or mixed flow fan is a backward curved radial fan.

12. Radial, axial or mixed flow fan according to any of the claims 6 to 11, wherein the rotor (16) comprises a spin ring (22), which is arranged coaxially around the rotation axis (R) and directly adjacent to the end part (30).

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