GB2079373A - Air guide member for flow machines - Google Patents

Abstract

An air guide member 24 for suppressing the noise of blowers, fans or like flow machines, has a cross-section formed by at least one concentric annular row of flow passages separated from each other by substantially radial wall sections which extend obliquely in the axial direction. Each annular row (21) consists of a plurality of identical preformed individual members which define a respective passage 20. The members support each other and are bundled together to form an annularly closed and centered flow unit. <IMAGE>

Description

SPECIFICATION Guide member or air guide member for flow machines The invention relates to an air guide member for suppressing the noise of blowers, fans or like flow machines, having a cross-section formed by at least one concentric annular row of flow passages separated from each other by substantially radial wall sections which extend obliquely in the axial direction. The member can be applied to machines operating with different flow media.

Known air guide members of the aforementioned kind have a construction which prevents the formation of an axially continuous flow path. This is for example achieved by the multiple spatial deflection of the flow within the air guide member. Deflection in the radial and circumferential direction is effected by guide ribs which are inserted in the flow passages or made in one piece therewith.

The formation or insertion of these guide ribs in the air guide member places narrow limits on the shape of the deflecting passages. Thus, optimum guiding of the flow from a streamlining point of view cannot be achieved or obtained only with considerable expense in the manufacture or during assembly. Further, the guide ribs cannot be of double wall construction and connecting apertures between the individual passages are possible only at positions which do not give rise to problems during extrusion.

To permit economical production of the known air guide member, the course of the passages should be as simple as possible but this has a negative influence on the efficiency.

It is therefore the problem of the invention to provide an air guide member which is cheap to produce, permits an optimum guide forthe flow and noise suppression, and the assembly of which is very much simplified.

According to the invention there is provided an air guide member for suppressing the noise of blowers, fans or like flow machines, having a cross-section formed by at least one concentric annular row of flow passages separated from each other by substantially radial wall sections which extend obliquely in the axial direction, characterised in that each annular row consists of a plurality of identical preformed individual passages which support each other and are bundled together to form an annularly closed and centered flow unit.

Since each annular row is composed of a plurality of identical self-supporting individual passages, the assembly of the air guide member can take place in a simple manner and in the radial direction even in the case of individual passages having multiple curves.

Further, when made by injection moulding, only one tool is required for each annular row. This tool can be made more economically because the moulding to be produced has a closed profile and because its free cross-section can be formed by a relatively strong core of the tool. Stripping of the moulding is simplified so that even complicated passages adapted to provide an optimum flow guide can be moulded without excessive manufacturing costs.

Juxtapositioning of these individual passages automatically forms double-walled ribs which contribute to the damping effect. The sub-division into segments makes it easy to assemble this plurality of individaul passages into a unit and very little labour is required.

Preferably the individual passages of one annular row and/or adjacent annular rows support each other by way of moulded-on spacing webs by which the walls of the individual passages can be located at a certain spacing from each other to form double walls. Preferably also damping material is inserted in the double walls. These features result in a particularly favourable construction. By means of the webs according to the invention, there is formed between the adjoining walls of the individual passages a cavity into which a soundproofing auxiliary material may be placed which brings about an improved effect if transverse holes are formed in the walls of the individual passages.

The flow units may be centered and bundled by way of annular flanges which can be pushed on from the respective ends of the air guide member. This leads to particularly favourable location of the flow units, it being possible to assemble the air guide member in a simple manner to form a preassembled unit. These bundling and centering flanges are also well suited for secure coupling to the housing of the flow machine.

In one embodiment the adjacent wall sectins of the individual passages can be located in their mutual position by means of a snap connection. Preferably each snap connection is formed by a spring collar which projects from one side and can be plugged with a snap effect into a socket formed in the adjoining wall, a flow aperture remaining within the collar and socket in the plugged-together condition.

This construction leads to a particularly favourable construction of the walls of the individual passages so that the assembly of the flow units is considerably simplified. The snap connections ensure that the air guide member can be assembied without auxiliary assembling means and is at the same time given an increased stiffness.

Further developments are evident from other subsidiary claims.

Several examples of the invention will now be described in more detail with reference to diagrammatic drawings, wherein: Figure 1 is a longitudinal section through an axial take-in radial blower with an upstream air guide member according to the invention; Figure 2 is a fragmentary section through the Figure 1 air guide member on the line Il-Il; Figure 3 is a fragmentary elevation of the Figure 1 air guide member viewed in the direction of the arrow III; Figure 4 is a pictorial view of a pre-assembled annular row of flow passages of an air guide member according to Figures 1 to 3; Figure 5 is a section through the air guide member of Figure 3 along the line V-V (developed view); Figure 6 is an enlarged representation of the detail VI in Figure 5; and Figure 7 is a section similar to Figure 5 through a further embodiment of the air guide member having straight individual passages.

The right-hand portion of Figure 1 illustratesthe front end or suction side of a radial blower comprising the rotor 1, outer housing 2 and outlet passages 3. An air guide member 4 according to the invention is flange-connected to the outer housing 2 by means of an annular abutment member 5. The axial pressure is applied through an inner pressure flange 15.

By means of this air guide member, the front side of the blower is screened from the outside, the special cross-sectional shape of the flow passage resulting in a slower intake flow at the inlet of the guide member and an accelerated flow, possibly with pre-rotation, at the outlet of the air guide member.

The air guide member is a body rotationally symmetric to the rotary axis of the rotor 1 and having a flow cross-section 6 which is curved to S shape in the axial direction. The flow is thus guided in the form of an S lying on its side and the flow cross-section diverges continuously starting from the inlet cross-section 7 of the rotor 1, outwardly towards the inlet cross-section 8 of the air guide member 4. The curvature of the guide faces 11 or 13 is selected so that the outlet and inlet cross-sections of the air guide member are radially covered.

However, it is also possible to use air guide members having equal flow sections at the outlet and inlet and of equal radial extent. To prevent axially continuous flow paths, these air guide members have substantially radial guide ribs 12 which extend obliquely to the axis of the air guide member so as to coverthe individual partial inlet and outlet crosssections.

Figure 2 shows that in the Figure 1 construction there is also deflection in the circumferential direction, i.e. twist of the flow. The radial or almost radial guide ribs 12 extend in a manner such that there is screw-like twisting of the flow passages 9 in the circumferential direction to an extent larger than one pitch 14.

As shown in Figure 3, the air guide member 4 is composed of a plurality of individual passages 20a and 20b which are bundled to form concentric annular rows 21 a and 21 b, respectively. All individual passages 20a, b of one annular row 21 a, bare of identical construction. In general, the individual passages have a twisted rectangular tubular shape.

The side walls 22a, b of the individual passages 20 form the guide ribs 12. The circumferential walls 23a, b form the outer and inner guide face 10 and 13, respectively as well as a guide rib 16 which is substantially parallel to the guide faces. In this way no axially directed flow path can be created within the guide member 4.

The individual passage segments 20a and 20b are so shaped that their abutting walls support each other as is best shown in Figure 4. Annular flanges 30 and 31 which are pushed onto the pre-assembled flow unit 24 from the outside and then for example cemented into position locate the individual segments 20 to form a pre-assembled unit. In the Figure 1 embodiment, this function of location is assumed by the annular abutment member 5 as well as the inner pressure flange 15.

To increase the damping effect, the mutual support may, in accordance with Figure 5, take place by way of webs 32 which ensure that cavities 34 are created between the individual walls 22 and 23 of the passages 20. This is effective for uncoupling the passages 20 from each other from an oscillating point of view and they function with less noise.

Connecting holes 33 in the walls 22 and 23 of the passages 20 ensure that communication necessary for flow mechanics is created between the individual passages 20. The cavity 34 can be insulated by means of a suitable soundproofing material 35.

An aid for assembly is to locate the individual juxtaposed passages 20 by way of a plug connection. Figures 5 and 6 show a possible construction of such a plug connection in the radial walls 22 of the passages 20. The plug connection is in the form of a snap connector 40 which also has the function of setting the spacing between two adjoining passages 20. Each part of the plug connection for this purpose comprises a spring collar 41 and a socket 42 which can be interconnected and locked together by means of a profile 43 on the outside of the spring collar 41 and on the inside of the socket 42. A free space 44 remains within the plug connection 40; it intercou ples the passages 20. The socket 42 also functions as a spacer and ensures that the passages assume a mutually stable position.

Figure 7 shows the same fixing device for a case where the individual passages 20 cannot bring about radial flow deflection.

Assembly of the air guide member 4 is desirably such that one first assembles the innermost flow unit 21 b whilst inserting damping material between the walls of the individual passages, the other individual passages of the adjoining flow unit being then presented thereto in the radial direction. In addition to or alternatively to the snap connection, the individual passages may also be cemented together to obtain a compact structural group. The flanges 30 and 31 can likewise be adhered in position or welded to the individual passages and then clamped to the housing 2.

Claims (9)

1. An air guide member for suppressing the noise of blowers, fans or like flow machines, having a cross-section formed by at least one concentric annular row of flow passages separated from each other by substantially radial wall sections which extend obliquely in the axial direction, characterised in that each annular row (21) consists of a plurality of indentical preformed individual passages (20) which support each other and are bundled together to form an annularly closed and centered flow unit (24).

2. An air guide member according to claim 1 wherein that in the case of a plurality of flow units (21 a, 21 b), these are arranged concentrically with the circumferential wall sections (23a, 23b) supporting each other.

3. An air guide member according to claim 1 or claim 2, wherein the individual passages (20) of one annular row (21) and/or adjacent annular rows (21 a,21 b) support each other by way of moulded-on spacing webs (32) by which the walls (22,23) of the individual passages (20) can be located at a certain spacing from each other to form double walls (34).

4. An air guide member according to claim 3, wherein damping material (35) is inserted in the double walls (34).

5. An air guide member according to claims 1 to 4, wherein the flow units (24) are centered and bundled by way of annular flanges (30,31) which can be pushed on from the respective ends of the air guide member (4).

6. An air guide member according to claims 1 to 5, wherein adjacent wall sections (22,23) of the individual passages (20) can be located in their mutual position by means of a snap connection (40).

7. An air guide member according to claim 6, wherein each snap connection (40) is formed by a spring collar (41) which projects from one side and can be plugged with a snap effect into a socket (42) formed in the adjoining wall (22,23), a flow aperture (44) remaining within the collar and socket (40,41) in the plugged-together condition.

8. An air guide member according to claims 1 to 7, wherein adjoining individual passages (20) are cemented together.

9. An air guide member according to claim 1 substantially as described herein with reference to the accompanying drawings.