Centrifugal aspirator with sealing means

Abstract

 An aspirator (1) comprises a stator (2, 3) shaped as a volute, provided with lateral walls (4), fitted with cap (5), for the entry of air within its interior; and a rotor (6) with blades (8) housed in the stator or volute (2, 3) and supported by a motorised shaft (7). The aspirator (1) further comprises seal means (35; 11, 12, 13) interposed between the stator (2, 3) and the rotor (6) and so shaped as to encompass at least the external envelopment surface (9) of the blades (8) of the rotor (6), in correspondence with related end bands (10) adjacent to the caps (5).

Description

[0001] The present invention relates to the construction of centrifugal aspirators and in particular of centrifugal aspirators destined to equip aspirating hoods for kitchens.

[0002] In the construction of aspirating hoods for home environments, a general problem area, universally known, is represented by the need to have aspirators that are capable of aspirating rather large flow rates of gasses, with adequate delivery pressures, low energy consumption and with modest sound emission levels, such as to minimise nuisance to any persons present in the room where the aspirating hood is located.

[0003] Within this general scope, there are aspirators that essentially comprise two half-shells so shaped as to define, when associated in mutual opposition, a volute stator, provided with lateral openings fitted with caps. Inside the stator is set a motorised blade rotor, whose rotation determines: the entrance of air into the volute through the lateral caps; the circulation of air circumferentially to the volute; and the subsequent expulsion of the air from the volute, through an outlet.

[0004] In a first aspirator of this kind, each of the half-shells of the volute and the related caps is configured as a single body. The bladed rotor is completely free within the volute, in the sense that there is no physical separation between the fixed walls of the stator or volute and of the related caps and the lateral surface of the rotor that peripherally envelops the blades thereof.

[0005] In correspondence with the periphery of the caps, and within the stator or volute, the stator itself is provided with edges so shaped as to embody a mouthpiece that projects coaxially to the rotor, within it, for a short initial segment of the axial length of the rotor itself.

[0006] Between rotor and edge of the half-shell inserted therein, sufficient clearance exists to avoid the movable rotor from rubbing against the immovable edge of the stator.

[0007] A second type of aspirator has its functional structure substantially identical to the one described above, but is distinguished therefrom because it has constructively distinct caps, separate from the half-shells. Conventional fastening elements allow the mutual association of caps and half-shells, thereby globally forming the stator or volute.

[0008] Both types of aspirators support with one of their caps a motor for the actuation of the rotor.

[0009] In the aspirators of the types described above, the pumping efficiency is negatively influenced by the possibility for air to recirculate rather easily from the internal volume of the volute, surrounding the rotor, notoriously at high pressure, towards the inlet section of the caps, which instead is subject to a much lower local pressure, close to atmospheric pressure.

[0010] Said recirculation is also intensified in the presence of high resistance opposing the exhaust of the gases, due for instance to the length of the conduit for the exit of the gasses, connecting the hood to the chimney, and/or the presence of local resistance constituted by junction elbows, variations in the passage sections, and so on.

[0011] To compensate for said functional inefficiency while providing users with performance levels that are suitable for the applications in question, it becomes necessary to adopt voluminous motors which, being supported by one of the caps, obstruct to a considerable extent the air inlet section, further contributing to induce additional elements of inefficiency in the aspirator.

[0012] The aim of the present invention is to overcome said drawbacks by means of an aspirator comprising a volute shaped stator, provided with at least a lateral opening, fitted with cap open to the transit of air within its interior; and a blade rotor housed in the stator or volute, and supported by a motorised shaft, characterised in that it comprises seal means, interposed between the stator and the rotor and shaped to encompass at least the external envelopment surface of the blades of the rotor, in correspondence with related end bands adjacent to said one or each cap.

[0013] The technical characteristics of the invention, according to aforesaid aims, are clearly noted from the content of the claims set out below and its advantages shall become more readily apparent in the detailed description that follows, made with reference to the accompanying drawings, which represent an embodiment provided purely by way of non limiting example, in which:

• Figure 1 is a perspective exploded view of an aspirator according to the invention;
• Figure 2 is a cross section of a half-shell of a first embodiment variation of the aspirator of Figure 1;
• Figure 3 is a cross section of a half-shell of a second, alternative embodiment variation of the aspirator of Figure 1.

[0014] With reference to the figures of the accompanying drawings, in Figure 1 the reference number 1 globally designates preferably, but not exclusively, intended for use in aspirating hoods for home kitchen environments B which essentially comprises a stator or volute globally designated as 2, 3, a rotor 6 with blades 8 and seal means, globally designated as 35, interposed between the stator 2 and 3 and the rotor 6.

[0015] The stator or volute is constituted by two half-shells 2 and 3, each whereof is provided with lateral openings 4, provided with cap 5 conveniently grilled for the transit of air.

[0016] The two half-shells 2 and 3 can be associated with each other in mutual opposition, thereby unitarily defining a global centrifugal volute having an inlet section subdivided in the opposite lateral openings 4 of the half-shells and a single outlet section 18, which instead is positioned in correspondence with the periphery of the volute.

[0017] Inside the centrifugal volute, the aspirator 1 houses a rotor 6 with blades 8 which is supported in overhang, in correspondence with a central disk 22 at one end of a motorised shaft 7, moved by a motor 17 in turn supported by one of the caps 5. For purposes of the present invention, the shape of the rotor 6, the type of blades 8 and the orientation of the blades 8 on the rotor 6 can be the most general.

[0018] Between the stator 2 and 3 and the rotor 6, the aspirator 1 is provided with seal means, globally designated as 35, able to prevent the recirculation of fluid between spaces of the aspirator 1 subjected to different pressures.

[0019] More in particular, said seal means 35 are shaped to encompass the external envelopment surface 9 of the blades 8 of the rotor 6, at least in correspondence with related end bands 10 of the rotor 6 adjacent to the caps 5. In accordance with a first embodiment of the invention, shown in Figure 2, said seal means 35 comprise annular elements 11 so shaped as to have, in correspondence with their meridian section, a first 12 and a second wing 13, mutually orthogonal and made in a single body.

[0020] The first wing 12 faces the surface 9 of envelopment of the blades 8, i.e. the lateral surface of the cylindrical rotor 6. The second wing 13 instead faces a contiguous base surface 14 of the same rotor 6.

[0021] The annular elements 11 embody dynamic labyrinth seals which integrally contour the circumferential edges of the rotor 6 preventing the passage of gasses through any gaps which put in geometric communication the internal part of the volute with the external air inlet section, through the caps 5.

[0022] The annular element 11 are also associated to a half-shell 2 or 3 of the stator or volute, preferably by being removably fastened. This is achieved in particular by a lateral edge 20 which, as shown in Figure 2, comes to abut against the respective half-shell when the annular element 11 is introduced in the respective lateral opening 4, with a motion directed from the exterior towards the interior of the half-shell.

[0023] The same Figure 2 also shows that the second wing 13 of the annular elements 11 provides an abutment and seal also to an edge 19 of the cap 5 when the cap is associated to the stator or volute.

[0024] Figure 2 also clearly shows that in the present solution B, unlike prior art solutions, the edge 19 remains totally outside the rotor 6 and hence, not having a need to be introduced into the rotor 6, it is wholly independent from the geometry thereof. This is particularly advantageous, since the edge 19 can be dimensioned in such a way as to have even greater passage diameter than the outer diameter of the rotor 6. This allows on one hand to have at the exterior of the cap 5 a more ample useful passage surface; and on the other hand it allows the most ample constructive freedom for the converging path guiding the gasses which conveys said gasses from the outermost face of the cap 6 to the interior of the bladed rotor 6.

[0025] In Figure 3, an alternative embodiment of the seal means 35 provides two distinct annular elements 11 which respectively bear: one, the second wing 13 which opposes the base surface 14 of the rotor 6; and the other one, the first wing 12 which instead opposes the lateral surface of the rotor 6. One of the annular elements 11, in particular the one that bears the second wing 13, is housed in the lateral opening 4 of the half-shell with insertion from the exterior towards the interior until its own lateral edge 20 abuts against the opposite face of the half-shell itself.

[0026] The other annular element 11 is instead associated to the same half-shell of the stator from the internal side, with exactly opposite motion until it is removably engaged to the half-shell by it own teeth 15 which enter corresponding slots 16 of the half-shell and which in mutual combination define generic fastening means 40 with rapid snap-on coupling, operating between the annular elements 11 and the stator or volute 2, 3.

[0027] The Figure 1 also shows that, to avoid all possibilities of air recirculation from the delivery chamber to the intake section of the aspirator 1 (forced vortex), the annular element 11 is provided with a terminal end 21 which abuts against the portion of wall of the volute locally opposite thereto.

[0028] The seal means 35 described above allow, in addition to the advantage of a drastic reduction in the pumping losses of the aspirator 1, with the benefit of an increased efficiency over known solutions destined to similar uses, also the advantage of a considerable enlargement of the useful surface of the caps 5 for introducing the air into the stator or volute 2, 3. Figures 2 and 3 show that the presence of the annular elements 11 allows to provide the caps 5 with a diameter that is not geometrically constrained by the maximum diameter of the rotor 6.

[0029] Such a characteristic is particularly advantageous above all for the cap 5 that supports the motor 17, notoriously more penalised by the bulky presence of the motor.

[0030] This characteristic, advantageous in itself, together with the greater pumping efficiency allowed by the seal means 35 allows to process, all other condition being equal, the air flow rates normally required by this kind of applications with less powerful motors which, advantageously, can also be made with cylindrically shaped frames and smaller dimensions than those of the conventional motors currently in use. Said characteristic, while on one hand allows to obtain aspirators of more economical construction and operation, on the other hand allows further to enhance ventilation efficiency as a consequence of the lesser bulk of the air passage surface in the cap 5 supporting the motor 17.

[0031] Such greater efficiency allows further advantages, such as: a more silent operation; smaller geometric dimensions which make the aspirator less bulky than prior art types; and the capability to use both considerably smaller motors, and motors able to operate even at low voltage.

[0032] The invention thus conceived is susceptible for evident industrial application; moreover, it can be subject to numerous modifications and variations, without thereby departing from the scope of the inventive concept that characterises it. Moreover, all components can be replaced by technically equivalent elements.

Claims

1. Aspirator comprising a stator (2, 3) shaped as a volute, provided with at least a lateral opening (4) fitted with cap (5) for the entry of air within it; and a rotor (6) with blades (8) housed in the stator (2, 3) or volute and supported by a motorised shaft (7), characterised in that it comprises seal means (35; 11, 12, 13) interposed between the stator (2, 3) and the rotor (6) and shaped to encompass at least the exterior envelopment surface (9) of the blades (8) of the rotor (6) in correspondence with related end bands (10) adjacent to said one ore each cap (5).

2. Aspirator, as claimed in claim 1, characterised in that the seal means (35) comprise an annular element (11) so shaped as to have, in correspondence with its own meridian section, at least a first wing (12), opposite to the surface (9) of envelopment of the blades (8), or lateral surface of the rotor (6).

3. Aspirator, a claimed in claim 1 or 2, characterised in that the seal means (35) comprise an annular element (11) so shaped as to have, in correspondence with its own meridian section, at least a second wing (13) opposite to a contiguous base surface (14) of the rotor (6).

4. Aspirator, as claimed in claim 3, characterised in that the annular elements (11) have said first (12) and second wing (13) made in a single piece.

5. Aspirator, as claimed in claims 1 or 2 or 3 or 4, characterised in that the annular elements (11) are associated to the stator or volute (2, 3).

6. Aspirator, as claimed in claim 5, characterised in that the annular elements (11) are removable from the stator or volute (2, 3).

7. Aspirator, as claimed in claim 6, characterised in that it comprises removable fastening means (40; 20; 15, 16) operating between the annular elements (11) and the stator (2, 3) or volute.

8. Aspirator, as claimed in claim 7, characterised in that the removable fastening means (40) include an edge (20) borne by a said annular element (11) and able to abut against the stator (2, 3).

9. Aspirator, as claimed in claim 7, or 8, characterised in that said fastening means (40) include teeth (15) and slots (16) indifferently associated to the annular elements (11) and to the stator or volute (2, 3).

10. Aspirator, as claimed in one of the previous claims in which said one or each cap (5) is removable from the stator or volute (2, 3), characterised in that the second wing (13) of said annular elements (11) offers an abutment against said cap (5) when it is associated to the stator or volute (2, 3).

11. Aspirator, as claimed in any of the previous claims, in which a said cap (5) supports a motor (17) for actuating the rotor (6), characterised in that said motor (17) is provided with a cylindrical frame.

12. Aspirator, as claimed in any of the previous claims, characterised in that said annular element (11) is provided with a terminal end (21) which abuts the portion of wall of the volute that is locally opposite thereto.

Drawing