Fan with a rotor and a fan impeller

Abstract

A fan (1) has a rotor (10) and a fan impeller (20). The rotor (10) has a connecting portion (11) and the fan impeller (20) has a fastening portion (21). The impeller is centered relative to the rotor (10) with the fastening portion (21) on the connecting portion (11) by at least one centering element (40). The impeller is fixed to the rotor (10) by at least one fastening element (30). The fastening element (30) is a screw with a screw head (31), a threaded portion (33), and a shaft arranged between the threaded portion (33) and the screw head (31). A spacer sleeve (34) is arranged around the shaft. A thread (12) corresponding to the fastening element (30) is, respectively, formed in the connecting portion (11).

Claims

1. A fan comprising: a rotor rotatable about an axis of rotation and has a connecting portion, a fan impeller has a fastening portion corresponding to the connecting portion and, the fastening portion is centered on the connecting portion, by at least one centering element relative to the rotor, the at least one centering element is an asymmetrical arrangement, the fastening portion is fixed to the rotor by at least one fastening element and the fan impeller arranged in a single predetermined arrangement on the rotor by the centering element; the fastening element is a screw with a screw head, a threaded portion, and a shaft, the shaft is arranged between the threaded portion and the screw head, a spacer sleeve is arranged around the shaft, an outer diameter of the spacer sleeve is smaller than an outer diameter of the screw head; and thickness of the spacer sleeve is smaller, by a predetermined amount, than a thickness of the fastening portion, a thread, corresponding to the fastening element or an opening corresponding to the fastening element is, respectively, formed in the connecting portion, and a through opening, corresponding to the spacer sleeve is, respectively, formed in the fastening portion, and the fastening portion is also made of a deformable material, so that when the screw is screwed into the thread, the spacer sleeve is guided into the through opening, a predetermined preload force of the screw is supported via the spacer sleeve against the connecting portion, and the fastening portion is clamped to the connecting portion in an area adjoining the through opening where the screw head rests against the fastening portion.

2. The fan as set forth in claim 1, wherein the thickness of the spacer sleeve and the thickness of the fastening portion, and/or the outer diameter of the spacer sleeve, an inner diameter of the corresponding through opening, and an outer diameter of the screw head are coordinated with one another in such a way that, when the screw is screwed into the thread, the fastening portion is pressed in a predetermined manner against the connecting portion with the predetermined preload force.

3. The fan as set forth in claim 1, wherein the fastening portion and/or the fan impeller are made of a plastic.

4. The fan as set forth in claim 1, wherein the spacer sleeve is rotatable relative to the screw and/or held by the screw on the shaft.

5. The fan as set forth in claim 1, wherein the spacer sleeve is made of a deformable material, so that when the screw is screwed into the thread, the outer diameter of the spacer sleeve is increased with the predetermined preload force and deformed as it presses against the fastening portion.

6. The fan as set forth in claim 1, wherein the spacer sleeve has a knurling on an outer surface pointing in the radial direction toward the fastening portion.

7. The fan as set forth in claim 1, wherein a plurality of fastening elements and/or a plurality of centering elements are distributed in the circumferential direction around the axis of rotation.

8. The fan as set forth in claim 1, wherein the centering element is a centering projection that is arranged or formed on the fastening portion and extends through a corresponding centering opening formed by the connecting portion, or wherein the centering element is a centering projection that is arranged or formed on the connecting portion and extends through a centering opening formed by the corresponding fastening portion.

9. The fan as set forth in claim 1, wherein a plurality of centering elements, each embodied as a centering projection, taper conically and/or are star-shaped in a cross section to their longitudinal axis (L).

10. The fan as set forth in claim 1, wherein a plurality of centering elements are distributed asymmetrically around the axis of rotation in the circumferential direction, so that the fastening portion and the connecting portion are arranged in a predetermined orientation that is encoded by the asymmetrical distribution.

11. The fan as set forth in claim 1, wherein the respective through opening and/or the spacer sleeve has a lead-in slope.

Description

DRAWINGS

(1) Other advantageous further developments of the disclosure are identified in the dependent claims or presented below together with the description of the preferred embodiment of the disclosure with reference to the figures.

(2) FIG. 1 is a cross-section view of a fan.

(3) FIG. 2 is an exploded plan view of an area around a fastening element and a centering element on a fan.

(4) FIG. 3 is a cross-section view through a fastening portion and a connecting portion in the vicinity of a fastening element.

(5) FIG. 4 is a cross-section view through a fastening portion and a connecting portion in the vicinity of a centering element.

(6) FIG. 5a is a front perspective view of a fan.

(7) FIG. 5b is a rear perspective view of a fan.

(8) FIG. 6a is a front perspective view of a fan impeller.

(9) FIG. 6b is a rear perspective view of a fan impeller.

(10) FIG. 7 is a cross-section view through a rotor.

(11) FIG. 8 is a cross-section through a fan.

DETAILED DESCRIPTION

(12) The figures are schematic examples. The same reference symbols in the figures indicate same functional and/or structural features.

(13) FIG. 1 shows a fan 1, more specifically a rotor 10 and a fan impeller 20 of the fan 1, in a view from below. A connecting portion 11 that is embodied as a rotor flange is visible. The fastening portion 21, embodied here as an impeller flange, is covered by the connecting portion 11. Clearly visible, in particular, is an asymmetrical arrangement of the centering elements 40. Three centering elements 40 are distributed over the circumferential direction around the axis of rotation A. Thus, the fan impeller 20 can be arranged only in a single predetermined alignment on the rotor 10. The fastening portion 21 can be arranged only in a single predetermined alignment on the connecting portion 11. Deviating therefrom, five fastening elements 30, distributed uniformly in the circumferential direction, are provided in the present case to uniformly clamp the rotor 10 and the fan impeller 20 to one another.

(14) An enlarged section of FIG. 1 is shown in FIG. 2. A fastening element 30 and a centering element 40 are shown directly adjacent to one another. The star-shaped cross section of the centering projection 23 can be seen from the illustration. Since this is also a view from below, the screw protrudes with its threaded portion 33 through the connecting portion 11.

(15) The sectional view of FIG. 3 shows a fastening element 30 clamping the fastening portion 21 to the connecting portion 11. The fastening element 30 is formed substantially by a screw and a spacer sleeve 34. The spacer sleeve 34 is rotatably held on the screw. The spacer sleeve 34 is held on a shaft 32 that lies between a screw head 31 and a threaded portion 33 of the screw.

(16) The screw 30 is, particularly, a thread-forming screw that is designed to cut or furrow a thread in the opening (bore) corresponding to the screw. It is inserted with its threaded portion 33 into a thread 12 that is formed for this purpose by or in the connecting portion 11 or screwed into a hole corresponding to the screw and not yet having a thread before screwing-in. As a result of the screwing, the spacer sleeve 34 migrates into a corresponding through opening 22 in the fastening portion 21. In the present case, the outer diameter D2 of the spacer sleeve 34 corresponds substantially to the inner diameter of the through opening 22.

(17) Because a diameter of the shaft 32 is smaller than an inside diameter D1 of the spacer sleeve 34, the latter can be freely rotated on the shaft 32 or the screw can be freely rotated relative to the spacer sleeve 34.

(18) The thickness H2 of the fastening portion 21 is preferably only slightly greater than the thickness H1 of the spacer sleeve 32. Thus, the screw head 31 initially comes to rest against the fastening portion 21 when it is screwed in. The screw head 31 presses the fastening portion 21 against the connecting portion 11 before the preload force, that is required for the screw, is achieved through a contacting of the screw head 31 against the spacer sleeve 34 or via the spacer sleeve 34 against the connecting portion 11.

(19) The clamping force or surface pressure applied by the screw head 31 to the fastening portion 21 is also determined by the contact surface of the screw head 31 on the fastening portion 21. The contact is annular and dependent on the outer diameter D4 of the screw head as well as on a diameter D3 that is determined by the through opening 22 and, if present, a lead-in slope of the through opening 22.

(20) In addition, the fastening portion 21 can be deformed at least in the area of the contact surface. Thus, it additionally presses against the outer surface of the spacer sleeve 34.

(21) FIG. 4 shows a section through a centering element 40 that is instantiated by a centering projection 23. It is formed by the fastening portion 21 and by a centering opening 13 that is formed by the connecting portion 11. The slightly conical centering projection 23 tapers toward its end along its longitudinal axis L starting from the fastening portion 21.

(22) In order to enable a greater tolerance in the manufacture of the mutually facing surfaces of the connecting portion 11 and of the fastening portion 21, one or a plurality of projections 25 can be provided on one of the surfaces, as is shown in FIG. 6b, for example. These projections 25, which have a flat surface relative to the plane of separation between the connecting portion 11 and the fastening portion 21, can be provided adjacent to or surround a fastening element. Accordingly, the fastening portion 21 in FIG. 4 is already in its final assembly position or in its predetermined positioning relative to the connecting portion 11. Thus, a gap between them is nevertheless discernible but is predetermined by the plateau-like projection 25 formed by the fastening portion 21.

(23) It can also be seen in FIG. 4 that the connecting portion 11 forms a circumferential fold 14 that stiffens the connecting portion 11. Furthermore, stiffening ribs 24 are included on the fastening portion 21 or the fan impeller 20, as is shown for example in FIGS. 5a and 6a. The ribs 24 can also extend around the areas around the fastening elements 30 or the screw heads 31.

(24) Therefore, neither the connecting portion 11 nor the fastening portion 21 need be a simple flange that extends exclusively on one plane.

(25) FIGS. 5a and 5b each show a perspective representation of a fan 1. More particularly of the fan impeller 20 and rotor 10, according to FIGS. 1, 2, and 4. FIG. 5a shows a view from above and FIG. 5b shows a view from below.

(26) As explained previously, FIG. 5a shows that the fan impeller 30 has a multiplicity of stiffening ribs 24 that reinforce the fastening portion 21. The reinforcing ribs 24 directly encircle the screw heads 31. Recesses 26 are provided in the fastening portion 21 for the purpose of weight reduction.

(27) In FIGS. 6a, and 6b, only the fan impeller 20 without the rotor 10 is shown in perspective view from above and below. In particular, FIG. 6a shows the plateau-like projections 25 that define the parting plane between the fastening portion 21 and the connecting portion 11. The projections 25 are arranged in a ring around a through opening 22. The clamping effect or force, via the screw heads 31, is thus produced or transferred exclusively via the plateau-like projections 25.

(28) FIG. 7 shows a rotor 10 isolated and in section. A round centering opening 12 can be seen that includes a centering projection 22 that receives a star-shaped cross section. It can also be seen that the thread 12 is embodied as an internal thread in an opening or as a bore or passage through a thread-forming screw. The thread 12 extends with an edge out of the surrounding plane of the connecting portion 11.

(29) In FIG. 8, the rotor 10 and the fan impeller 20 can be seen before or during their assembly. The fastening portion 21 is guided onto the connecting portion 11 and brought into the predetermined positioning or angular position. This enables the centering projections 23 to engage in the corresponding centering openings 13.

(30) If the fastening portion 21 and the connecting portion 11 are moved further toward one another, the fastening portion 21 can be guided by the centering elements 40 into position. Subsequently or at the same time, the fastening elements 30 can be inserted and their threaded portion 33 can be screwed into the corresponding thread 12. As a result of the screwing-in, more particularly screwing-home, the spacer sleeves 34 are introduced into the corresponding through openings 22 and preferably pressed in. Then the screw head 31 first comes to rest against the fastening portion 21 and presses same against the connecting portion 11. The screw head 31 comes into contact with the spacer sleeve 34 through a minimal deformation of the fastening portion 21. While the screw head 31 is supported by the spacer sleeve 34 on the connecting portion 11, it builds up a preload force that was predetermined for a screw.

(31) The disclosure is not limited in its execution to the abovementioned preferred exemplary embodiments. Rather, a number of variants are conceivable that make use of the illustrated solution even in the form of fundamentally different embodiments.

(32) The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.