EP3592985B1 - Parts kit and method for producing a radial blower - Google Patents

Description

The present invention relates to a set of parts for the production of a radial fan and its use.

A centrifugal fan typically has a housing with a chamber in which a fan rotates about an axis, an inlet opening adjacent to the axis, and an outlet opening located at the periphery of the chamber.

The relationship between the speed of the fan wheel, the pressure difference between the inlet and outlet openings and the volume flow depends on the geometry of the fan wheel and the chamber containing it and is a characteristic of every fan model. The requirements for this connection vary depending on the application for which the radial fan is intended. If a fan is used for cooling purposes, for example, then its volume flow should vary as little as possible with the pressure difference in order to be able to maintain a sufficient cooling air flow even under unfavorable conditions, e.g. when the cross section of the cooling air path is restricted. If, on the other hand, a fan is used to ventilate a patient, then a strong dependence of the volume flow on the pressure difference is desired in order, on the one hand, to be able to provide a high volume flow when the patient breathes in, but on the other hand not to hinder his exhalation due to a high counter pressure .

Traditionally, these opposing needs are met by designing different fans for cooling or ventilation. The housing parts specific to these fans are only required in small quantities and therefore have high unit costs.

State of the art in the present technical field is disclosed, for example, in the publications US 4,902,199A , CN 104 251 229 A , DE 203 09 621 U1 US 2007/059167 A , DE 10 2016 001 484 A , US 2007/247009 A1 and CN 103 486 085 A .

The aim of the present invention is to create a set of parts and a method with which fans can be provided cost-effectively with a relationship between pressure difference and volume flow that is adapted to a specific application.

The task is solved on the one hand by the features of claim 1.

If the fan wheel is specifically optimized in a suitable manner with regard to a desired relationship between pressure and volume flow and is required in several versions in order to be able to represent different relationships, an application-specific modification of the housing parts can be dispensed with. Cost advantages arise, on the one hand, from the fact that the non-application-specific parts can be provided cost-effectively in large quantities, but also from the fact that the application-specific fan wheels are necessarily smaller than the housing parts that delimit the wheel chamber that accommodates them, and therefore with small-format, relatively simple ones and accordingly cost-effective tools can be manufactured.

The advantage of simple production comes into play particularly when the fan wheels each have a base plate and the base plate have blade blades that protrude in the axial direction with free edges facing away from the base plate, since these can generally be formed with only two tool parts that can move relative to one another in the direction of the axis, while for the production of the housing parts, especially if they have locking means that interact with one another, also in Tool parts that move in the radial direction are required.

If the inlet opening is provided in the complementary housing part, then when one of the fan wheels is mounted in the wheel chamber, its base plate should face the base housing part and the blades should face the complementary housing part (3).

The outlet should lie approximately in the plane of the fan wheel and is therefore expediently delimited on the one hand by the base housing part and on the other hand by the complementary housing part.

To ensure interchangeability of the fan wheels, they should all have identical interfaces for attachment to a motor shaft. These interfaces can be, for example, passages with an identical, non-round cross section into which the shaft can be inserted in a torque-locking manner, or flanges spaced along the axis on both sides of a passage, which, for example, allow the fan wheel to be clamped between a shoulder of the shaft and a screwed-on nut.

Between the free edges of the blades of a fan wheel mounted in the wheel chamber and a wall of the complementary housing part delimiting the wheel chamber, a gap inevitably extends over which air flows back to the inlet if there is a sufficient pressure difference between the inlet opening and the outlet, which affects the throughput of the fan. In order to improve the efficiency of the fan, the complementary housing part has a structure that extends concentrically around the axis on the wall delimiting the wheel chamber on, and the fan wheels are provided with contours on the free edges of their blades, which form a labyrinth seal with the concentric structure. For example, the concentric structure can be a circumferential groove, which is opposite to projections on the edges of the blades, or the concentric structure can have a projection extending around the axis, which is opposite to recesses in the free edges.

In order to obtain different pressure-volume flow characteristics for the different fan wheels, according to the invention the first and second fan wheels differ in the number and/or the length of the blades. Other features, such as the shape of the base plate, the axial extent of the blades, their wall thickness or the course of their free edges, can remain the same from one fan wheel to the other within the limits set by the manufacturing accuracy.

The effort for construction and for the production of molds for the various fan wheels can be limited by the fact that the shape of the second fan wheel is derived from that of the first fan wheel by adding at least one blade, i.e. that the first fan wheel is used in the production of the second The shape used would fit in and fill it apart from the added blade.

In order not to restrict the free cross section - and thus the volume flow - of the fan too much through additional blades, the radius of an end near the axis of the added blade should be larger than that of an end near the axis of at least one blade of the first fan wheel.

The blades of each fan wheel necessarily have an inner edge oriented transversely to the air flow direction, past which the blown air enters a channel between two air blades. As can be seen from the previous paragraph, this distance can be used for Blade wheels of a single fan wheel can be different. In order to obtain different forms of the pressure-volume flow characteristic curve, such as in one case a low dependence of the volume flow on the pressure, in the other case a strong dependence, it is useful if the set of parts includes two fan wheels, which are separated by the distance between the ones closest to their axis distinguish inner edge from the axis.

In order to achieve a strong increase in pressure between the inlet opening and outlet, the inner edge closest to the axis of at least one fan wheel should lie at least partially within a cylinder that is concentric to the axis and whose diameter corresponds to the diameter of the inlet opening.

Conversely, for a high variability of the volume flow with low pressure fluctuations, it is useful if the inner edge closest to the axis of at least one fan wheel lies outside this cylinder.

The fan wheel is preferably mounted on the base housing part, opposite the inlet opening of the complementary housing part.

Installation space for a motor driving the fan wheel is also expediently provided on the base housing part.

• Bereitstellen eines Teilesatzes wie oben beschrieben,
• Auswählen eines der Lüfterräder des Teilesatzes; und
• Zusammenfügen des ausgewählten Lüfterrads mit dem Grundgehäuseteil und dem komplementären Gehäuseteil.

The task is further solved by a method for manufacturing a radial fan with the following steps

• Providing a set of parts as described above,
• Selecting one of the parts kit's fans; and
• Assembling the selected fan wheel with the basic housing part and the complementary housing part.

Fig. 1

einen erfindungsgemäßen Teilesatz in einem auseinandergezogenen axialen Schnitt;

Fig. 2

eine Draufsicht in axialer Richtung auf ein Grundgehäuseteil und ein Lüfterrad des Teilesatzes;

Fig. 3

ein vergrößertes Detail des fertigen Lüfters in einem radialen Schnitt;

Fig. 4-7

Draufsichten auf verschiedene Lüfterräder des Teilesatzes; und

Fig. 8

Druck-Volumenstromkennlinien von verschiedenen Lüfterrädern.

Further features and advantages of the invention result from the following description of exemplary embodiments with reference to the attached figures. Show it:

Fig. 1

a set of parts according to the invention in an exploded axial section;

Fig. 2

a top view in the axial direction of a basic housing part and a fan wheel of the set of parts;

Fig. 3

an enlarged detail of the finished fan in a radial section;

Fig. 4-7

Top views of various fan wheels in the parts set; and

Fig. 8

Pressure-volume flow characteristics of different fan wheels.

Fig. 1 shows an exploded view of a basic housing part 1, a fan wheel 2 and a complementary housing part 3 of a radial fan. The cutting plane of the Fig. 1 runs along an axis of rotation 4 of the fan wheel 2.

The basic housing part 1 comprises a base plate 5, an outer wall 6 and an elastic buffer ring 7, via which the base plate 5 is connected to the outer wall 6 to form an outer cup. An electric motor 9 is accommodated concentrically in the outer cup, forming an annular cooling air channel 8, and is enclosed by an intermediate wall 11 supported on a shoulder 10 of the outer wall 6.

The electric motor 9 comprises a shaft 12, a rotor 13, a stator 14, a circuit board 15 which carries an inverter for supplying the stator 14, and a housing which encloses the mentioned components 12-15. The housing comprises an inner cup 16 and a lid 17 which closes the inner cup 16 and through whose central opening the shaft 12 projects.

The intermediate wall 11 and the cover 17 exposed in an opening in the intermediate wall form a central plateau 18 around the axis of rotation 4. An edge region of the intermediate wall 11 surrounding the plateau 18 springs back into the interior of the outer cup and, together with the outer wall 6, delimits a channel 19 , which extends around the axis of rotation 4 with a cross-section that gradually increases along the circumference of the cup.

The fan wheel 2 has a base plate 20 oriented transversely to the axis of rotation 4, the diameter of which is not larger than that of the plateau 18. One side of the base plate 20 lies closely adjacent to the plateau 18 in the assembled state. An axial passage 47 of the fan wheel 2 is provided to receive the end of the shaft 12. In the case shown here, the passage 47 is formed in a sleeve made of metal, in particular brass, onto which the base plate 20 and blades 21 of the fan wheel 2 are molded, and whose inner diameter is coordinated with the diameter of the shaft 12 so that the fan wheel 2 passes through Can be mounted on the shaft 12 by pressing.

Blade blades 21 protrude in the axial direction on a side of the base plate 20 facing away from the plateau 18. This side can be in the shape of a cone or a hyperboloid of revolution.

In the view of Fig. 2 The basic housing part 1 and the fan wheel 2 mounted on the shaft 12 can be seen in a top view. You can clearly see the channel 19, which, starting from a starting point 22, gradually widens, extends in a counterclockwise direction around the fan wheel 2 and merges into an outlet 23 branching off tangentially to the circumference of the fan wheel 2. The blades 21 have the shape of ribs which extend spirally from an inner end 33 facing the axis of rotation 4 to the edge of the base plate 20.

The intermediate wall 11 has one or more openings 24 through which the channel 19 communicates with the cooling air duct 8 near the starting point 22. These openings 24 are in Fig. 2 covered by the fan wheel 2 and therefore shown with dashed lines. Another passage 25 between the channel 19 and the cooling air duct 8 is located at the outlet 23.

The rotation of the fan wheel 2 generates a higher pressure in front of the passage 25 than at the openings 24, so that air enters the cooling air duct 8 via the passage 25, absorbs waste heat from the motor 9 there and leaves the cooling air duct 8 again via the openings 24. A radial wall 26 between the motor 9 and the outer wall 6 divides the cooling air channel 8 and forces the sucked in air to almost completely circle the motor 9 on the way from the passage 25 to the openings 24.

The complementary housing part 3 has an end wall 28 which extends around an inlet opening 27 about the axis of rotation 4, the funnel-shaped inner surface 29 of which, in the assembled state, lies opposite the free edges 30 of the air blades 21 facing away from the base plate 20 at a short distance. The funnel-shaped inner surface 29 extends radially beyond the edge of the base plate 20 and meets an inside of the outer wall 6. The end wall 28 thus delimits a wheel chamber 31 in the fully assembled fan, in which the fan wheel 2 rotates, as well as, together with the Channel 19, a blown air channel 32 extending around the wheel chamber 31, in which the rotation of the fan wheel 2 generates an excess pressure.

Due to the spiral shape of the blades 21, the course of the free edges 30 of the blades 21 is in a radial section through the fan wheel 2, as in Fig. 1 shown, difficult to see. Fig. 3 shows a section along the axis of rotation 4 and a radius through the complementary housing part 3 and a rotating body obtained by rotating the fan wheel 2 about the axis of rotation 4. Here you can see It is clear that the edges 30, starting from the inner end 33, first run steeply towards the end wall 28 along an inner edge 40 and then, beyond a vertex 41, along a large part of their length together with the inner surface 29 of the end wall 28, a gap 42 of essentially limit constant width.

The inner surface 29 is divided by a flat groove 43 into an inner and an outer section 44, 45, both of which are convexly curved. The channel 43 is opposite projections 46 on the edges 30 of the blades 21. If a high pressure difference between outlet 23 and inlet opening 27 drives a backflow of air along the gap 42 to the inlet opening 27, then this tends to move the channel 43 in a direction tangential to both sections 44, 45 (in Fig. 3 indicated by a thin dashed line) and comes under the influence of the blades 21. This means that a high pressure difference between the outlet 23 and the inlet opening 27 can be maintained at a given speed of the fan wheel 2.

Up again Fig. 1 An annular flange 34 extends around the inner surface 29 perpendicular to the axis of rotation 4. A flange 35 lies opposite it on an upper edge of the outer wall 6. Both flanges 34, 35 each have an annular groove 36. A sealing ring 37, which engages in both annular grooves 36 in the assembled state, seals the blown air channel 32 radially to the outside.

On the circumference of the complementary housing part 3, brackets 38 projecting over the flange 34 are distributed. These are intended to accommodate projections 39 (see Fig. 1) when assembling the housing. Fig. 2 ) to be snapped onto the outer wall 6 of the basic housing part 1 and thus permanently connect the housing parts 1, 3 to one another.

It would also be conceivable to replace one or two of the brackets 38 and projections 39 with a foil hinge through which the two housing parts can be folded on top of each other after attaching the fan wheel 2.

Fig. 4 shows the fan wheel 2 of the Fig. 1 and 2 once again on its own, to make it clearer how this fan wheel 2 differs from others Fig. 5-7 shown fan wheels 2, 2", 2'" of the parts set according to the invention differs and in which the fan wheels are similar.

The diameter of the base plate 20 and the shape of the passage 47 receiving the shaft 12 are identical for all fan wheels, and preferably also the curvature of the side of the base plate 20 carrying the blades 21. The blades 21 of the fan wheel 2 are also on the fan wheels 2 ', 2 " the 5 and 6 The number, wall thickness and course of the edge 30 are identical. At the fan wheel 2' Fig. 5 There is a blade in every space between two blades 21, in the case of the fan wheel 2". Fig. 6 two additional blades 21' each inserted. The additional blades 21' double or triple the frequency with which an outer end of a blade sweeps past the starting point 22 and causes turbulence there, compared to the fan wheel 2. In addition, the additional blades 21' block the space that the turbulence needs. to be able to spread and thereby dampen them strongly. The result of this is, on the one hand, a dampening of the flow noise of the fan wheel, and on the other hand, an increase in frequency, which shifts part of the operating noise spectrum out of the audible frequency range when the fan speed is suitable. Both contribute to the fact that the fan wheels 2 ', 2" have reduced operating noise compared to the fan wheel 2.

The additional blades 21' narrow the passage cross section of the wheel chamber 31 and thereby lead to higher flow losses and lower efficiency. Therefore, a user will generally select the fan wheel 2 for commercial applications in already noisy environments where operating costs are low are an important criterion, whereas the paddle wheels 2', 2" are preferred for applications in the private sector where a strong operating noise is clearly noticeable.

In order to limit the loss of efficiency, the inner ends 33 'of the additional blades 21' are arranged at a greater distance from the axis 4 than the inner ends 33 of the blades 21. While the inner edges 40 of the blades 21 are largely within the radius r the inlet opening 27, corresponding edges 40 'of the additional blades 21' lie outside.

The fan wheel 2'" the Fig. 7 is very similar to the fan wheel 2' Fig. 5 . The number of blades is the same on both; The difference between the two is that in the case of the fan wheel 2'", the inner ends 33 of all blades 21' lie beyond the radius r of the inlet opening 27.

Fig. 8 illustrates the influence of these design differences using the pressure-volume flow characteristics of the fan wheels 2, 2" and 2"'. The characteristics are shown in arbitrary units, as the values differ in individual cases depending on the dimensions of the fan wheels and the speed; However, they are recorded for fan wheels with the same dimensions at the same speed and are therefore comparable. The strongest dependence of the volume flow V on the pressure difference □p is with fan wheel 2. This is therefore well suited to infer the volume flow from the easily and reliably measurable pressure increase and to generate a predetermined volume flow by controlling the speed depending on the pressure. The 2" fan wheel achieves the highest values of volume flow and pressure in comparison and is therefore suitable for building a fan with high power density. With the 2'" fan wheel - especially in the lower volume flow range - the dependence of the pressure increase on the volume flow is low; Therefore, a fan with this fan wheel can limit pressure fluctuations in an application with fluctuating volume flow, for example in a The ventilator prevents strong increases in pressure if the volume flow is interrupted during the patient's exhalation phase, thus enabling calm inhalation afterwards.

Reference symbols

1

Basic housing part

2

Fan wheel

3

complementary housing part

4

Axis of rotation

5

base plate

6

external wall

7

Buffer ring

8th

Cooling air duct

9

Electric motor

10

shoulder

11

partition wall

12

Wave

13

rotor

14

stator

15

Circuit board

16

Mug

17

Lid

18

plateau

19

gutter

20

base plate

21

Shovel blade

22

starting point

23

outlet

24

opening

25

passage

26

radial wall

27

Inlet opening

28

Front wall

29

Inner surface

30

Edge

31

Wheel chamber

32

Blown air duct

33

inner end

34

flange

35

flange

36

Ring groove

37

sealing ring

38

hanger

39

head Start

40

inner edge

41

Vertex

42

gap

43

gutter

44

inner section

45

outer section

46

head Start

47

passage

Claims (13)

1. A set of parts for a radial fan, having a first fan wheel (2), a main housing part (1), and a complementary housing part (3), which can be assembled to form a wheel chamber (31) surrounding the fan wheel (2) and comprising an inlet opening (27) and an outlet (23), wherein at least one second fan wheel (2', 2",...) is provided, the shape of which differs from that of the first fan wheel (2) and which can be mounted rotatably about an axis (4) into the wheel chamber (31) instead of the first fan wheel (2), characterized in that the complementary housing part (3) comprises a structure (43-45) concentrically extending about the axis (4) on the wall (28) defining the wheel chamber (31), in that the fan wheels (2, 2', 2", ...) have contours (46) on their free edges (30) of their vane blades (21, 21'), which contours form a labyrinth seal with the concentric structure (43-45), and in that the first and the second fan wheels (2, 2', 2", ...) differ in the number and/or length of the vane blades (21, 21').
2. The set of parts according to claim 1, characterized in that the fan wheels (2, 2', 2",...) have a base plate (20) and vane blades (21) projecting in the axial direction from the base plate (20) with free edges (30) facing away from the base plate (20).
3. The set of parts according to claim 1 or 2, characterized in that the inlet opening (27) is provided in the complementary housing part (3) and in that, in the mounted state of one of the fan wheels (2, 2', 2", ...) its base plate (20) faces the main housing part (1) and its vane blades (21) face the complementary housing part (3).
4. The set of parts according to any one of the preceding claims, characterized in that the outlet (23) is defined by the main housing part (1) and the complementary housing part (3).
5. The set of parts according to any one of the preceding claims, characterized in that the fan wheels (2, 2', 2", ...) have identical interfaces (47) for fastening to a shaft (12) of a motor (9).
6. The set of parts according to any one of the preceding claims, characterized in that the shape of the second fan wheel (2', 2", ...) is derived from that of the first fan wheel (2) by adding at least one vane blade (21').
7. The set of parts according to claim 6, characterized in that the radius of an end (33') near the axis of the added vane blade (21') is greater than that of an end (33) near the axis of at least one vane blade (21) of the first fan wheel (2).
8. The set of parts according to any one of the preceding claims, characterized in that the vane blades (21, 21') of each fan wheel (2, 2', 2", ...) have an inner edge (40, 40') oriented transversely to the direction of the air flow, and in that the set of parts includes two fan wheels (2, 2'"), which differ by the distance of their respective inner edge (40, 40') closest to the axis from the axis (4).
9. The set of parts according to claim 8, characterized in that the inner edge (40) closest to the axis is in at least one fan wheel (2, 2`, 2") at least partially inside a cylinder concentric with the axis (4), the diameter of which cylinder matching the diameter of the inlet opening (27).
10. The set of parts according to claim 8 or 9, characterized in that the inner edge (40') closest to the axis is in at least one fan wheel (2‴) outside a cylinder concentric with the axis (4), the diameter of which cylinder matching the diameter of the inlet opening (27).
11. The set of parts according to any one of the preceding claims, characterized in that the fan wheel (2, 2', 2", ...) is mounted to the main housing part (1).
12. The set of parts according to any one of the preceding claims, characterized in that an installation space for a motor (9) is provided in the main housing part (1).
13. A method for producing a radial fan, comprising the steps of:

    Providing a set of parts according to any one of the preceding claims;

    selecting one of the fan wheels (2, 2', 2", ...) of the set of parts; and

    assembling the selected fan wheel, the main housing part (1), and the complementary housing part (3).

Images