EP2857693A1 - Fan assembly for machine for floorcare - Google Patents

Abstract

The invention relates to a fan assembly, comprising a fan housing in which a motor is arranged, which is connected via a shaft with an impeller, wherein on the side facing away from the motor of the impeller, a cover plate is placed, wherein the impeller by an attachable to the fan housing fan shroud is covered, wherein the fan cover has a suction opening, on which a circumferential bead is arranged, which is open in the direction of the fan wheel.

Description

The invention relates to a fan assembly, comprising a fan housing in which a motor is arranged, which is connected via a shaft with an impeller, wherein on the side facing away from the motor of the impeller, a cover plate is placed, wherein the impeller by an attachable to the fan housing fan shroud is covered, wherein the fan cover has a suction opening, on which a circumferential bead is arranged, which is open in the direction of the fan wheel.

In such a blower arrangement, the impeller generates a pressure difference, which leads to a negative pressure at the intake opening. This simultaneously results in an overpressure in the space extending between the impeller and the blower housing from the outer periphery of the impeller to the suction port of the blower housing. The pressure difference between these two areas leads to the inevitable gap between the fan housing and the inner peripheral edge of the cover plate of the impeller to a backflow of a portion of the delivered air flow. On the one hand, the loss of air flow due to the backflow significantly reduces the efficiency of the blower and, on the other hand, increases the temperature in the blower.

To improve the efficiency of the blower, it is known to use the closest tolerances at the gap between the blower housing and the inner peripheral edge of the cover disk of the blower wheel, thereby reducing the backflow of the conveyed air. This is very costly and due to technically necessary tolerances within a mass production often only limited feasible. Other measures such as the arrangement of labyrinths or sealing elements at the gap between positive pressure and low pressure side are very expensive to manufacture and lead to only small increases in efficiency of a blower.

From the DE 197 17 154 A1 It is known to fill the gap between the fan housing and the inner peripheral edge of the cover plate of the impeller by a firmly adhering elastic sealant. Although such a sliding sealing element made of elastic material prevents backflow of the suction air, but leads to unacceptable disadvantages in the operation of the fan. By melting or abrasion of the elastic sealant occur disturbing noise and odor emissions of the fan. In addition, the onset of wear of such a sliding sealing element results in a gap between the positive pressure and negative pressure side of the blower, whereby its efficiency drops significantly.

The invention thus presents the problem of providing a blower arrangement which effectively seals the gap between the blower housing and the inner peripheral edge of the cover disk of the blower wheel while avoiding the disadvantages mentioned.

According to the invention, this problem is solved by a device having the features of patent claim 1 and by a method having the features of patent claim 8. Advantageous embodiments and further developments of the invention will become apparent from the following subclaims.

The blower arrangement for a floor care appliance is characterized in that in the bead at the suction opening, a circumferential sealing ring consisting of PU or PUR foam is arranged which sealingly surrounds a radially inner portion of the cover pane. In this case, the PU or polyurethane foam is applied in the bead surrounding the intake opening of the fan cover circumferentially, so that there is a sealing ring with the dimensions of the bead. The sealing ring is designed so that it surrounds a radial portion of the cover plate sealingly in the final assembled state of fan housing and fan shroud. In this case, the portion or portion of the cover plate is sealingly enclosed by the PU or polyurethane foam of the sealing ring, which is arranged approximately parallel to the axis of rotation of the blower. The sealing enclosure of the radially inner portion of the cover plate through the PU or PUR foam takes place in the final assembled state of fan shroud and blower housing by cutting the cover plate in the sealing ring. By cutting the cover plate into the sealing ring, the PU or PUR foam is displaced so that the radially inner portion of the cover plate is sealingly surrounded by the PU or PUR foam. The cutting of the cover plate in the sealing ring made of PU or PUR foam takes place in such a way that there is a minimal gap between the cover plate and the sealing ring.

The arrangement of a sealing ring made of PU or PUR foam in a bead on the suction port allows an effective and permanent sealing of the gap between the impeller and the suction port of the fan shroud. By cutting and displacing the PU or PUR foam through the cover plate, there is a minimal gap between the radially inner portion of the cover plate and the sealing ring. As a result, the backflow occurring at the fan wheel of the delivered air volume is limited to a minimum and increases the efficiency of the fan to a significant extent. The gap between the cover disc and sealing ring, which is produced in the final assembled state of fan housing and fan cowl, also ensures a non-contact seal. This prevents abrasion or melting of the sealant during operation of the blower. In this way, disturbing noise or odor emissions can be excluded by the sealing ring.

Another advantage of the arrangement of a sealing ring made of PU or PUR foam consists in the balance of existing in a large-scale production tolerances between impeller and Gebläsehaube. Tolerances with respect to the impeller height or the alignment of the fan shroud to the axis of rotation of the impeller are circumvented by the cutting of the cover plate in the sealing ring on the resulting end position and have no effect on the sealing function of the sealing ring.

Preference is given to a blower arrangement in which a sealing ring made of PU or PU foam surrounds a radially inner section of the cover disk in a sealing manner on the upper, lower and front sides thereof. In the final assembled state of Gebläsehaube and blower housing, the cover plate cuts so far in the PU or polyurethane foam of the sealing ring that results in a surface seal the top, bottom and end of the radially inner portions of the cover. In other words, the sealing function of the fan assembly does not take place via a line contact between the cover plate and sealing element, but via a surface overlap between the PU or PUR foam and the top, bottom and end side of the radially inner portion of the cover plate. As a result, the sealing performance of the sealing ring and thus the efficiency of the fan assembly are further increased.

It is additionally preferred that the sealing ring circumferentially has approximately the height of the bead. For this, the PU or PU foam is introduced into the bead at the suction opening, so that the foam has approximately the height of the bead wall, which faces the intake opening of the fan cover. The PU or PUR foam is bordered on three sides by the walls of the bead in the fan cowl and is only openly accessible from the side facing the fan wheel.

The circumferential arrangement of the sealing ring of PU or PUR foam in approximately height of the bead has the advantage that this allows a longer surface coverage between the sealant and the radially inner portion of the cover plate of the impeller. The further the cover plate cuts into the PU or PUR foam of the sealing ring, the longer becomes the surface coverage between the sealant and the top and bottom of the cover plate. By extending the surface coverage on these two sides of the cover plate, the sealing function of the sealing ring and thus the efficiency of the fan assembly are increased.

In addition, the arrangement of the PU or PUR foam in the bead is advantageous because by the three-sided enclosure of the sealant through the bead walls unwanted damage to the sealing ring in the context of manufacturing or transportation can be excluded as far as possible. In addition, the three-sided enclosure of the sealing ring in combination with the adhesive effect of the PU or PUR foam prevents unintentional detachment of the sealing ring during operation or assembly of the blower. As a result, there is no need in the context of manufacturing to support the adhesion of the PU or PUR foam by a previous washing or de-oiling of the fan shroud.

In a preferred embodiment of the blower arrangement, the sealing ring has different heights in sections. The PU or PUR foam is applied in the bead of the suction opening so that the PU or PUR foam has a structured height profile. That is, the sealing ring has individual portions which have a smaller distance in their spatial extent to the cover plate of the impeller than other portions of the sealing ring. The height profile of the sealing ring is so pronounced that in the final assembled state of the blower housing and fan shroud the radially inner portion of the cover plate is fully enclosed, sealing by PU or PUR foam.

In a particularly preferred embodiment of the blower arrangement, the sealing ring has an approximately wave-shaped height profile. The wave profile of the sealing ring has at least two wave troughs and two wave peaks in the circumferential direction. In a further preferred embodiment of the blower arrangement, the sealing ring has an approximately ramp-shaped height profile. The ramp profile has, for example, four individual ramps, which are distributed uniformly over the circumferential course of the sealing ring.

The arrangement of the PU or PUR foam in a structured height profile has the advantage that during the assembly of the fan assembly the forces acting on the impeller Eindrückkräfte be reduced. For example, the forces which axially occur when the cover disk is pressed into the PU or PUR foam do not impact the fan wheel in an intermittent manner, but are uniformly distributed over the entire press-in path of approximately 3 to 5 mm. In particular, the application of PU or PUR foam in a wave or ramp-shaped height profile ensures that the cover plate of the impeller does not have to cut through the skin layer of PU or PUR foam simultaneously along the entire circumference of the sealing ring. The occurring during assembly bearing loads of the impeller are thereby effectively reduced. In an alternative embodiment of the sealing ring, it is also conceivable to remove the skin formed on the surface thereof after the PU or PU foam has cured. In this way, the forces occurring axially when pressing in the cover plate in the polyurethane or polyurethane foam are also reduced.

The material of the sealing ring preferably has a strength of about 0.2 to about 2 N / mm ² . The use of a sealing ring made of PU or PUR foam in the stressed strength ensures that the cover plate of the impeller can be pressed with minimal force in the PU or PUR foam of the fan hood. This ensures that when pressing the radially inner portion of the cover disc no axially acting forces on the impeller occur, which could lead to its damage. In addition, we ensure that the cover disc of the impeller cuts into the PU or PU foam on the fan shroud to a sufficient extent and thus achieves a surface seal between the cover disc and the sealing ring. At the same time it is ensured by the use of a sealing ring made of PU or PUR foam in the claimed strength that the radially inner portion of the cover plate cuts into the PU or PUR foam so that a minimum gap between the cover plate and the PU or PUR foam of the sealing ring is created. The claimed strength of the PU or PUR foam ensures the dimensional stability of the sealing ring and in particular of the sealing gap between cover plate and PU or PUR foam safe. Thus, it is precluded that the shape of the PU or polyurethane foam and thus the sealing gap after the impressions of the cover plate further deformed and leads to a reduction of the sealing function of the sealing ring.

The material of the sealing ring is selected so that the material properties, characterized by the above values, even after aging under the operating conditions in a floor care device with continuous vibration load and elevated temperatures remain. A loss of the sealing function of the sealing ring as a result of embrittlement or aging of the sealing material can be excluded.

Furthermore, the sealing material has a hardness of about 15 to about 50 Shore. The use of a sealing material in the claimed hardness and strength has the advantage that a depression of the cover plate in the sealing ring is made possible without much effort. On the one hand, this reduces the forces that occur when pressing in the cover disk on the impeller. On the other hand, it is not necessary, as part of the depression of the cover plate, to set the impeller in rotation in order to assist the cutting of the cover plate in the PU or PUR foam.

A further aspect of the invention relates to a method for assembling such a blower arrangement, characterized by the following steps: (a) application of the PU or PUR foam into the bead of the intake opening of the blower hood; (b) allowing the PU or PUR foam to cure; (c) placing the fan shroud on the blower housing; (d) pressing the fan shroud onto the fan housing until the radially inner portion of the fan housing Cover disc cuts into the PU or PUR foam and is surrounded by this area sealingly.

The procedure for mounting a fan assembly with sealing element is shortened by the use of PU or polyurethane foam as a sealant. Thus, among other things, eliminates the steps of centering or caulking the sealing element, as required for example in sealing rings made of elastic material. In addition, a centering of the fan shroud is not required, since the PU or polyurethane foam compensates all occurring in a large-scale production tolerances between impeller and fan shroud by cutting the cover plate in a resulting end position. The caulking of the sealing element is eliminated due to the intrinsic adhesive effect of PU or PUR foam.

In addition, the requirement to place the fan shroud on the blower housing immediately after application of the sealing material by the use of PU or polyurethane foam as a sealing element. Known elastic sealing materials often have a relatively small time interval in that they are plastically deformable so that a sealing effect between the fan cover and the fan housing is ensured. Due to the associated higher demands on the production control or logistics, the production cost of such a fan assembly increases. Through the use of PU or PUR foam as a sealing element in the fan assembly eliminates this time restriction of the assembly of fan housing and fan shroud. This reduces the costs associated with the procedure.

Another advantage of the claimed fan assembly is that even without the application of PU or PUR foam in the bead on the suction port a socket sealing function between fan shroud and blower housing. That is, even if the arrangement of a sealing element made of PU or PUR foam is dispensed with, the engagement of the cover plate in the bead of the suction port is sufficient to ensure a basic sealing effect between fan shroud and blower housing. As a result, the claimed blower arrangement has an acceptable efficiency even without a sealing element made of PU or PUR foam. As part of the manufacture of the fan assembly, this results in the advantage that the fan shroud can be used as a common part flexible with or without sealing element of PU or PUR foam.

Additionally preferred is a method in which after curing of the PU or PUR foam and before placing the fan shroud on the blower housing, the skin layer of the PU or PUR foam is removed. In this case, the layer of PU or PUR foam is removed, which forms on the surface of the sealing ring after curing. Particularly preferred in this case is a mechanical removal of the skin layer of the PU or polyurethane foam. The removal of the skin layer of PU or PUR foam reduces the force required to push the cover plate into the sealing ring. At the same time, the forces acting on the impeller in the axial direction as part of the depression are reduced.

An embodiment of the invention is shown purely schematically in the drawings and will be described in more detail below. Corresponding objects or elements are provided in all figures with the same reference numerals. The or each embodiment is not to be understood as limiting the invention. Rather, in the context of the present disclosure, modifications and modifications are possible, which may be achieved by the combination or modification of individual features described in the general or specific description part and in the claims and / or the drawings with respect to those skilled in the art Solution of the task can be removed and lead by combinable features to a new object or to new process steps.

Figur 1

Schnittdarstellung eines Gebläses für einen Staubsauger mit einem Dichtring aus PU- oder PUR-Schaum;

Figur 2

vergrößerte Darstellung von Gebläsegehäuse und Gebläsehaube im endmontierten Zustand;

Figur 3

Schnittdarstellung des Dichtrings aus PU- oder PUR-Schaum mit Eingriff eines radial inneren Abschnitts der Deckscheibe;

Figur 4

vollumfängliches Höhenprofil eines wellenförmigen Dichtrings mit Darstellung des Einpressweges der Deckscheibe.

Show it:

FIG. 1

Sectional view of a blower for a vacuum cleaner with a sealing ring made of PU or PUR foam;

FIG. 2

enlarged view of blower housing and fan shroud in final assembled condition;

FIG. 3

Sectional view of the sealing ring made of PU or PUR foam with engagement of a radially inner portion of the cover plate;

FIG. 4

Full height profile of a wave-shaped sealing ring with representation of the press-in path of the cover plate.

FIG. 1 shows the sectional view of a fan assembly 10, in particular suitable for a vacuum cleaner. The blower arrangement 10 shown has a blower housing 12, which is closed by a laterally arranged motor partition 50. Blower housing 12 and motor partition 50 are centered to each other. Centrally centered in the fan housing 12, a motor 14 is arranged, which drives a fan wheel 18 via a shaft 16. The shaft 16 is rotatably mounted both in the fan housing 12 and in the motor partition 50. The shaft 16 connects the motor 14 with an impeller 18 that is disposed on the motor 14 side facing away from the motor partition 50. The impeller 18 is releasably but rotatably connected to the shaft 16.

The impeller 18 comprises a carrier disk on which axially projecting conveying blades are arranged. On the carrier disc opposite side of the conveyor blades, a cover plate 20 is placed. The cover plate 20 has centered on an opening. At the outer periphery of the impeller 18, the cover plate 20 is aligned approximately parallel to the carrier disk. In a radially inner portion of the impeller 18, the cover plate is aligned approximately parallel to the axis of rotation of the impeller 18.

The fan wheel 18 is covered on the opposite side of the motor partition wall 50 by a fan cover 22. The fan shroud is connectable to the blower housing 12 and / or the motor partition wall 50. The fan shroud 12 has centered on a suction port 24. Circumferentially around this intake opening 24, a bead 26 is arranged in the fan shroud 12, which is open in the direction of the blower housing 12. In the bead 26, a sealing ring 28 made of PU or polyurethane foam is arranged. The radially inner portion of the cover plate 20, which is aligned approximately parallel to the axis of rotation of the impeller 18, fully engages in the sealing ring of PU or PUR foam.

FIG. 2 shows an enlarged section of the fan assembly 10, as in FIG. 1 shown. The impeller 18 is connected to a shaft 16 which is driven by a motor 14, not shown. The fan wheel 18 is bordered on the side facing away from the motor by a fan cover 22, which centered centrally has an intake opening 24. During operation of the blower arrangement 10, the blower wheel 18 generates negative pressure which results at the suction opening 24 of the blower hood 22 in a suction air flow. At the same time, an overpressure arises on the outer circumference of the blower wheel 18 in the region between the cover disk 20 of the blower hood 22. In order to prevent a compensation of this pressure difference and thus a disturbing backflow of suction air into the suction opening 24, a sealing element 28 made of PU or PUR foam is arranged at the transition between the two areas. By the sealing element 28 made of PU or PUR foam, which is arranged in a circumferential bead 26 of the fan shroud 22, a return flow of suction air is prevented around the radially inner portion of the cover plate 20 into the suction port 24.

FIG. 3 shows an enlarged view of the sealing element made of PU or polyurethane foam, which sealingly separates the overpressure region 52 between cover plate 20 and fan cover 22 from the vacuum region 54 at the suction port 24 of the fan cover 22. Surrounding the suction opening 24 while a bead 26 is arranged, which is open only in the direction of the fan 18. In this bead 26, a sealing ring 28 made of PU or PUR foam is arranged, which adapts in its geometrical extent approximately to the shape of the bead. The height 36 of the bead 26 is defined by the outer boundary of the bead 26, which delimits the bead 26 of the suction port 24 of the fan cover 22.

The arranged in the bead 26 sealing ring 28 made of PU or PUR foam is from the direction in which the bead is opened, through the radially inner portion of the cover plate 20th recessed all around. The incision of the radially inner portion of the cover plate 20 takes place approximately over half the height 26 of the bead. This results in a surface sealing of the upper 30, lower 32 and front side of the cover plate 20 with respect to the PU or PUR foam of the sealing ring. This prevents suction air from the overpressure region 52, which is located between the underside 32 of the cover disk 20 and the fan cover 22, from flowing back into the vacuum region 54 on the top side 30 of the cover disk 20 in the suction region 24. Due to the peripheral cut of the radially inner portion of the cover plate 20 results in a planar overlap of the upper 30 and bottom 32 of the cover plate 20 with the sealing ring 28th

FIG. 4 shows the alternative embodiment of a sealing ring 28 for the claimed fan assembly 10, which has a structured, wave-shaped height profile. On the ordinate 42, the height profile of the sealing ring 28 is shown as a function of the circumference profile shown on the abscissa 44. The height profile of the sealing ring 28 has four wave peaks 46 and four wave troughs 48, which are arranged alternately at regular intervals. The geometric characteristics of the wave peaks 46 and wave troughs 48 are approximately identical over the entire circumferential course of the sealing ring 28.

FIG. 4 also shows the position of the cover plate 20 of the impeller 18 before 38 and after 40 the impressions of the cover plate 20 in the PU or polyurethane foam of the sealing ring 28. The position 38 of the cover plate before pressing into the sealing ring is characterized in that the cover plate 20 rests evenly on the crests 46 of the sealing ring 28. The position 40 of the cover plate 20 after impressions is characterized in that the cover plate has intersected the wave peaks 46 and the wave troughs 48 along the entire circumferential course of the sealing ring 28. The fact that the cover plate 20 has been pressed down to below the wave troughs 48 of the sealing ring 28, the cover plate 20 is surrounded by the PU or polyurethane foam sealingly.

LIST OF REFERENCE NUMBERS

10

blower assembly

12

fan housing

14

engine

16

wave

18

blower

20

cover disc

22

fan cowl

24

suction

26

Beading

28

seal

30

Top cover disk

32

Bottom cover disk

34

Front side cover disk

36

Height of the bead

38

Position the cover disc before pressing it into the sealing ring

40

Position cover disc after pressing into the sealing ring

42

ordinate

44

abscissa

46

Wellenberg sealing ring

48

Wellental sealing ring

50

motor bulkhead

52

Overpressure range

54

Under pressure range

Claims (9)

A fan assembly (10) comprising a fan housing (12) having a motor (14) disposed thereon connected to a fan wheel (18) via a shaft (16), the fan wheel side being remote from the motor (14) (18) a cover plate (20) is mounted, wherein the impeller (18) by a to the fan housing (12) attachable fan cover (22) is covered, wherein the fan cover (22) has a suction opening (24) on which a circumferential Bead (26) is arranged, which is open in the direction of the impeller (18),
characterized,
in that a circumferential sealing ring (28) made of PU or PUR foam (28) is arranged in the bead (26) on the suction opening (24) and sealingly surrounds a radially inner section of the cover disk (20). Blower arrangement (10) according to claim 1,
characterized,
in that the sealing ring (28) made of PU or PUR foam surrounds a radially inner section of the cover disk (20) in a sealing manner over its upper (30), lower (32) and end (34) surfaces. Blower assembly (10) according to claim 1 or 2,
characterized,
that the sealing ring (28) circumferentially approximately the height (36) of the bead (26). Fan arrangement (10) according to one of claims 1 to 2,
characterized,
that the sealing ring (28) has different heights in sections. Blower arrangement (10) according to claim 4,
characterized,
that the sealing ring (28) has an approximately undulating height profile. Blower arrangement (10) according to claim 4,
characterized,
that the sealing ring (28) has an approximately ramp-shaped elevation profile. Blower arrangement (10) according to one of the preceding claims,
characterized,
that the material of the sealing ring (28) has a strength of about 0.2 to 2 N / mm ² . Method for assembling a blower arrangement (10) according to one of the preceding claims, characterized by the following steps: (A) application of the PU or PU foam in the bead (26) of the suction port (24) of the fan hood (22); (b) allowing the PU or PUR foam to cure; (c) placing the fan shroud (22) on the fan housing (12); (D) pressing the Gebläsehaube (22) on the blower housing (12) until the radially inner portion of the cover plate (20) cuts into the PU or PUR foam and is surrounded surface sealingly therefrom. Method according to Claim 8, in which the following step is carried out between steps (b) and (c): (e) removing the skin layer of the PU or PUR foam.

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