DE102013208855B4 - radial fan housing - Google Patents

Abstract

The invention relates to a radial fan housing 1 with a housing interior 2 for accommodating a fan wheel 8, which can be rotated about an axis of rotation 9, and with a suction-side housing wall 16 with an inflow opening 18 through which the air to be conveyed can flow in the axial direction onto the fan wheel 8. The invention is based on the object of specifying a radial fan housing that allows the volume flow of air conveyed to be adjusted without additional components, such as throttle valves or screens. For this purpose it is provided that the position of the inflow opening 18 in relation to the axis of rotation 9 can be changed from a first 25 to a second position 30 .

Description

The invention is in the field of radial fans, in particular for household appliances such as tumble dryers and washer-dryers, which serve to convey air flows such as process air flows in tumble dryers or washer-dryers or cooling air flows.

The invention relates to a radial fan housing with a housing interior for accommodating an impeller that can be rotated about an axis of rotation, and with a suction-side housing wall with an inflow opening through which air to be conveyed can flow in the axial direction onto the impeller.

Such radial fan housing are from EP 0 702 105 B1 and EP 1 990 465 A1 known. These two publications describe a radial fan or a housing for such a radial fan in a household appliance, in particular a tumble dryer, with a radial fan wheel which is accommodated in a spiral-shaped housing interior and is mounted so as to be rotatable about its longitudinal axis. The air to be conveyed passes through an air duct to a housing wall of the radial fan on the intake side. In the housing wall, there is an opening or an air inlet for air access, coaxial to the longitudinal axis or axis of rotation of the impeller, which - if necessary through a funnel-shaped insert ( EP 0 702 105 B1 ) - directs the air sucked in by the impeller onto the inflow surface of the impeller or onto the center between the blades. This opening or this air inlet is also referred to as an inflow opening or nozzle.

Energy consumption and energy efficiency play an increasingly important role, especially in household appliances such as tumble dryers. Tumble dryers are classified according to their energy consumption and the accuracy in achieving a specified final residual moisture content. Depending on the load situation and the load quantity, the requirements for the process air conveyance can vary in the individual drying phases, so that an adjustment of the conveyed air flows is desirable for this reason. This means that the drying processes designed according to standard processes based on a full load and a half load can be better matched to the actual nominal load. Otherwise, it is to be feared that smaller loads will overdry and thus lead to an undesirable increase in energy consumption. If the loading quantity is known to the system, a simple influencing of the pumped volume flow is therefore desirable for energy optimization.

An adjustment of the conveyed volume flow can also be desirable to compensate for service life effects, such as fluff deposits and the resulting increase in pressure loss coefficient in the air-carrying system, in environmentally-related programs (with a correspondingly desired lower air throughput) or also in fast programs (with a correspondingly desired increased air throughput).

From a mechanical point of view, the geometric and physical design of the known radial fan housing determines the performance of the radial fan, in particular the air throughput or the volume flow, at a given nominal speed of the fan wheel. Controlling the volume flow conveyed by the known radial fan at a predetermined nominal speed, for example the process air in a tumble dryer, is fundamentally conceivable by flow and throughput influencing elements in the air duct, such as throttle valves. However, this requires a comparatively high outlay and additional components.

The present invention is based on the object of specifying a radial fan housing which satisfies the requirements outlined above in a simple manner.

According to the invention, this object is achieved by a radial fan housing having the features of the independent patent claim. Advantageous refinements of the invention result from the following description and from the attached drawing as well as from the dependent patent claims, the features of which can be used individually and in any combination with one another.

Accordingly, in a radial fan housing of the type mentioned at the outset, it is provided that the position of the inflow opening can be changed from a first to a second position in relation to the axis of rotation.

The invention is based on the surprising measure of realizing different delivery rates or volume flows with an otherwise unchanged geometric design and unchanged drive performance parameters of a radial fan through the relative radial positioning of the inflow opening in relation to a reference of the radial fan wheel - namely indicated here by the axis of rotation of the fan wheel. The invention can thus be used in all cases in which a variable process air flow or cooling air flow or an individual design or adjustment of the power of a radial fan to its respective operational tasks is required. This adjustment can be done by positioning the inflow opening relative to the impeller both once or only occasionally (e.g. at the factory or as part of a service) and regularly manually or automatically as required during operation of the device equipped with the radial fan housing according to the invention. In addition, appropriate adjustment can also be used to take into account the effects of the service life, which require a slow but constant increase in the delivery capacity of a radial fan over the service life.

With the present invention, by changing the position of the inflow opening depending on the desired operating point or the air transport quantities, a more effective (drying) process control can be implemented and adapted as required (e.g. "quiet" programs) and/or load status. This allows the air volume flow to be adjusted in a variety of flexible ways, in particular without requiring variations in the nominal speed and/or means influencing the air flow, such as throttles or flaps in the air duct. This allows a wide variety of fan or blower characteristics to be generated.

In addition, a standard radial fan with the housing according to the invention can be easily adapted to the performance requirements in the respective application, so that individual fan designs or different fan types are not required.

A configuration of the radial fan housing according to the invention that can be implemented particularly easily provides that the second position is an eccentric position in relation to the axis of rotation.

Particularly when a continuous and easy-to-implement change in the volume flow is desired in a radial fan, a further development of the invention is advantageous, according to which the movement of the inflow opening from the first to the second position takes place along an arc of a circle. In particular, both the first position and every second position are characterized by an eccentric arrangement of the inflow opening.

This can be implemented with particularly little effort in terms of design and operation or control in that a wall part of the housing wall containing the inflow opening can be rotated coaxially with the axis of rotation relative to the rest of the fixed housing wall or to the housing interior.

In this regard, according to a further advantageous embodiment of the invention, a particularly wide scope for adjustment can be realized in that the housing wall can be rotated through 360° relative to the housing interior.

In order to achieve a preferably automatic adjustment of the volume flow—for example as a function of the nominal load of a tumble dryer or washer-dryer—an advantageous development of the invention provides that an electromechanical drive causes the inflow opening to move. The movement of the inflow opening is particularly preferably reversible. It is also conceivable that the movement of the inflow opening takes place counter to a restoring force or a restoring moment, so that the inflow opening returns to a starting position when the movement control is complete.

The measures described above achieve a particularly strong effect if the interior of the housing is in a manner known per se ( EP 0 702 105 B1 ) Way is designed as a spiral housing interior.

The air supply opening can preferably be designed as a nozzle with a circular cross section. In principle, however, other opening geometries or shapes are also conceivable, in which case the above-described movements can then be related to the center point or the centroid of the respective opening area relative, for example, to the axis of rotation of the impeller.

Depending on its configuration and mounting, the axis of rotation of the impeller can be the actual, mechanical (drive) axis of the impeller or else a virtual axis of rotation about which the impeller rotates.

The movement of the inflow opening is preferably limited to a plane which is at a constant distance from the impeller or in the housing wall. In any case, with the position variance of the inflow opening, preferably with the help of an eccentric nozzle, the person skilled in the art is given a means of controlling the volume flow with otherwise unchanged operating parameters and geometric conditions of the radial fan and thus metering the conveyed air flow. This enables targeted and more effective drying process control in household appliances such as tumble dryers, depending on need and/or load status and program selection (e.g. gentle programs, low-noise programs, quick drying programs) are possible.

As described in more detail below using exemplary embodiments, the invention makes it possible to realize operating points with higher volume flows in comparison to the known prior art with a centrally arranged inflow opening. Apart from an electromechanical control system that may be desired for the positioning of the inflow opening, the invention does not require any additional components in the air duct systems. Overall, devices with increased energy efficiency and reduced operating noise can be implemented. The volume flow can be readjusted and kept constant with simple means, even if operationally (e.g. clogged fluff filters, fluffing up laundry) and life-related phenomena increase the pressure loss coefficient in the air duct system. Overall, these are also aspects that ensure increased customer satisfaction.

• 1: ein geöffnetes Radialgebläsegehäuse mit darin aufgenommenem Radialgebläserad,
• 2: das Gehäuse nach 1 mit entferntem Gebläserad,
• 3: eine Variante eines Radialgebläsegehäuses,
• 4: unterschiedliche Positionen einer Zuströmöffnung,
• 5: exemplarisch Ergebnisse von Versuchsreihen mit einem Radialgebläsegehäuse in der in 3 dargestellten Ausgestaltung, und
• 6: ein Radialgebläsegehäuse in Einbaulage.

The invention is explained in more detail below with reference to exemplary embodiments illustrated in figures in the attached drawing. Show it:

• 1 : an opened radial fan housing with a radial fan wheel accommodated therein,
• 2 : the housing after 1 with the impeller removed,
• 3 : a variant of a radial fan housing,
• 4 : different positions of an inflow opening,
• 5 : exemplary results of test series with a radial fan housing in the in 3 illustrated embodiment, and
• 6 : a centrifugal fan housing in installation position.

1 shows an embodiment of a radial fan housing 1, which is freed from a rear housing wall close to the viewer for better illustration. A housing interior 2 is delimited by a lateral housing wall 3 which, due to its course, in a manner known per se ( EP 0 702 105 B1 ) forms a spiral housing interior 4. A fan wheel 8 is accommodated in the housing interior 4 and is mounted so as to be rotatable about its central axis of rotation 9 in a manner that is not shown in detail. The impeller 8 can be driven in the direction of rotation 10 by a drive (not shown here) and conveys air (e.g. process air from a tumble dryer) through its blades 11 in a tangential or radial direction in relation to its axis of rotation 9, as shown by arrows 12, to an air outlet opening 14, to which an air duct, not shown, can be connected.

As 2 illustrated with the fan wheel removed, the radial fan housing 1 comprises a housing wall 16 on the suction side, in which an inflow opening 18 is formed. In this example, the inflow opening 18 is designed as a nozzle 19 with a circular cross section 20 and a nozzle or circle center 21 . The position of the inflow opening 18 can be changed in relation to the axis of rotation 9 . As in 2 shown by way of example, in a first embodiment, the inflow opening 18 can be moved or shifted from a first position 25 concentric with the axis of rotation 9 (indicated by dot-dash lines) by moving in the radial direction 26 radially outward into the second position 30 shown with a solid circular line 28. This can be implemented, for example, by a plate containing the inflow opening 18, which can be moved correspondingly on the outside 31 of the housing wall 16, for example guided by a link.

In 2 a variant is also indicated, which is also related to 3 is further described. The center point 21 and thus the inflow opening 18 can be moved along a circular arc shown with a dashed line 35 from the "4 o'clock" position 36 shown (the thick dashes shown here represent corresponding hour hand positions of a dial of an analogue clock only for better illustration). The inflow opening 18 can preferably be moved by a movement of the nozzle center point 21 on the circular arc 38 represented by the dashed line 35 around a partial circle or a full circle around a full rotation (360°). The inflow opening 18 can be moved along the circular arc—more precisely: by moving the nozzle center point 21 on the circular arc 38—to the positions “2 o'clock” 39 or “6 o'clock” 40 entered as an example. This variant can be realized in that the inflow opening 18 is formed in a wall part 42 of the housing wall 16 and this wall part 42 is mounted coaxially to the axis of rotation 9 relative to the rest of the housing wall 16 or relative to the housing interior 4 . For this purpose, the wall part 42 can be configured as a circular disk that is rotatably inserted into the housing wall 16 . This disc can be rotated by a servo or drive motor 43 to the desired position, so that the inflow opening 18 is in the desired position (nozzle position 44) in relation to the housing interior 4 or the impeller 8 ( 1 ) occupies.

In this configuration, the movement of the inflow opening or its positioning is reverse sible. Provision can also be made for the inflow opening to be moved from a rest position to the desired position by restoring means (e.g. spring-loaded) and then, if necessary, returned to the resting position by the restoring means.

In 3 Fig. 12 schematically shows an embodiment similar to that previously described 2 shown, with the lateral housing wall 3 of the otherwise only rudimentary shown radial fan housing 1 is indicated. The inflow opening 18 or nozzle is bent or funnel-shaped into the housing interior 4 . A drive shaft 46 of a drive motor, not shown, penetrates an air duct 47 for the incoming air and the nozzle 18 and drives the - in 3 removed - impeller on. The inflow opening 18 or nozzle is shown here in a position 50 in relation to the axis of rotation 9 at “3 o'clock”. Accordingly, for the later ( 5 ) for a more detailed explanation of the test series carried out, the further positions "6 o'clock", "9 o'clock" and "12 o'clock" corresponding to the dial of a clock are given.

The in 4 Position 51 shown at "4:30 a.m." served as the design position, at which the increases or decreases in the volume flow shown were measured at a given nominal speed and nominal density with a nominal nozzle diameter and a position variance between "6 o'clock" and "12 o'clock". With a reference value (design point) of the inflow opening in position 51 with a volume flow of 100%, the result is as in 4 increases or decreases in the volume flow can be seen depending on the position variance. It can be seen, for example, that in the "12 o'clock" position 52 of the inflow opening 18 there is a reduction in the volume flow of around 13 to 16%, while in the "6 o'clock" position 53 there is a change in the volume flow of around +/- 1 % could be determined.

5 shows further test series with one of the basic representation of the 3 corresponding radial fan housing. A total of 9 different positions of the inflow opening, identified by the respective designation of the corresponding hour hand position of an analogue clock, were measured comparatively here. As a reference, a centrally arranged inflow opening—that is, an opening with a center point 21 aligned coaxially with the axis of rotation 9—was examined. During this measurement on the test stand, an orifice was provided in the air duct and initially completely closed (maximum pressure increase, corresponding to the pressure values on the Y-axis). When the orifice is fully open, the volume flow values that can be seen for the optimal determination of the operating point are based on the individual points of the curves on the X-axis.

It can be seen that certain eccentric inflow opening positions ("3 o'clock" and "1:30 o'clock") show approximately equivalent results. In addition, there are also positions with higher relative to the reference (“4:30 a.m.”, “6 a.m.”), i.e. increasing the volume flow, as well as with significantly lower, the volume flow reducing delivery capacity (see, for example, “9 a.m.” and “10: 30 p.m.") recognizable. The above the pressure increase at nominal speed and nominal density in 5 The illustrated variance in the volume flows at nominal speed thus provides the expert with the means to carry out desired changes in the volume flow or compensations, e.g (see only example 5 ) can be generated. This also enables the use of a standard radial fan housing, which in this way can easily be adapted to different requirements with regard to its delivery capacity. This adjustment can already be made at the factory. Likewise, operational and demand-dependent changes in the conveyed volume flow, for example in household appliances, can easily be implemented.

6 Finally, for a better overview, FIG. In the housing interior 4 of the radial fan housing 1, the impeller 8 is shown with its blades 11, which is rotatably mounted about the axis of rotation 9 and driven by a motor shaft 60 (comparable to the drive shaft 46 according to 3 ) of an electric motor 61 can be driven. For this purpose, the motor shaft 60 penetrates the inflow opening 18, which is arranged eccentrically in relation to the axis of rotation 9. As described above, the inflow opening is formed in a wall part 42, which in turn can be displaced radially with respect to the axis of rotation 9, so that the inflow opening 18 can be moved out of the position 63 shown, if necessary into a different position relative to the axis of rotation in the vertical plane 64 (perpendicular to the plane of the drawing). During operation, inflowing process air 65 is supplied through a process air duct 66, deflected and enters the fan housing 1 through the inflow opening 18, as indicated by arrows 67. There the process air is funded in a known manner by the impeller 8 and radially, ie substantially vertical to the plane of the 6 accelerated and blown into a non-illustrated laxative air duct.

Reference List

1

radial fan housing

2

housing interior

3

housing wall

4

spiral housing interior

8th

impeller

9

axis of rotation

10

direction of rotation

11

shovels

12

arrows

14

air outlet opening

16

housing wall

18

inflow opening

19

jet

20

cross-section

21

nozzle center

25

first position

26

radial direction

28

circle line

30

second position

31

outside

35

line

36

"4 o'clock" position

38

circular arc

39

"2 o'clock" position

40

"6 o'clock" position

42

wall part

43

servo motor

44

nozzle position

46

drive shaft

47

air duct

50

position

51

position

52

position

53

position

60

motor shaft

61

electric motor

63

position

64

vertical plane

65

process air

66

process air duct

67

arrows

Claims (7)

Radial fan housing (1) - with a housing interior (2) for accommodating a fan wheel (8) which can be rotated about an axis of rotation (9), and - with a housing wall (16) on the suction side with an inflow opening (18) through which the air to be conveyed is to be conveyed can flow towards the impeller (8) in the axial direction, characterized in that - the position of the inflow opening (18) in relation to the axis of rotation (9) can be changed from a first (25) to a second position (30). Radial fan housing (1) after claim 1 , characterized in that - the second position (30) in relation to the axis of rotation (9) is an eccentric position. Radial fan housing (1) after claim 1 or 2 , characterized in that - the movement of the inflow opening (18) from the first (25) to the second position (30) takes place along a circular arc (38). Radial fan housing (1) according to at least one of the preceding claims, characterized in that - a wall part (42) of the housing wall (16) containing the inflow opening (18) can be rotated relative to the housing interior (4) coaxially to the axis of rotation (9). Radial fan housing (1) after claim 4 , characterized in that - the housing wall (16) can be rotated through 360° relative to the housing interior (4). Radial fan housing (1) according to at least one of the preceding claims, characterized in that - the movement of the inflow opening (18) is brought about by an electromechanical drive (43). Radial fan housing (1) according to at least one of the preceding claims, characterized in that - the movement of the inflow opening (18) is reversible.

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