GB2379959A

GB2379959A - An impeller assembly having fastened blades.

Info

Publication number: GB2379959A
Application number: GB0126185A
Authority: GB
Inventors: Francas Josep Palau
Original assignee: Soler and Palau SA
Current assignee: Soler and Palau SA
Priority date: 2001-09-19
Filing date: 2001-10-31
Publication date: 2003-03-26
Anticipated expiration: 2021-10-31
Also published as: GB0126185D0; GB2379959B; DE20214247U1; ES1050060Y; ITRM20020149U1; FR2829806B3; FR2829806A3; ES1050060U

Abstract

Impeller assembly having a central hub 1, a plurality of inclined blades 17, and a plurality of radial extensions 2, each provided with two cylindrical surfaces 7, extending from the central hub. At least one of the surfaces of the radial extension is provided with a centring recess (11 of Fig 4) and a threaded hole 21. The blades include a cylindrical surface (8 of Fig 3) matching that of the radial extension, and include a countersunk depression (10 of Fig 3) for fitting in the centring recess of the radial extension. The countersunk depression includes a hole for insertion of a screw 9 which passes through the threaded hole in the radial extension to fasten the blade to the hub. The blades may be fitted to obtain a reverse direction of flow.

Description

IMPELLER ASSEMBLY

The invention relates to an impeller assembly formed of a plurality of sheet-metal blades and a central hub which serves at the same time as the 5 rotor of an external rotor electric motor The use of sheet-metal blades fixed to a plurality of projections from a central hub for constructing impellers for air feed or extraction is known. To adapt said impellers to the desired flow performance, it is necessary to vary the inclination of the blades. This can only be achieved using central hubs 10 with more or less inclined projections or indeed with blades at different angles between the attachment zone and the working zone. Both solutions require high investment in moulds and equipment if it is intended to cover a reasonable range of flows.

The improved impeller assembly of the present invention comprises a 15 plurality of blades, preferably of sheet metal, and a central hub which may also serve as the rotor of an external rotor electric motor. The base member or hub may be the rotor of an external rotor electric motor with an external casing of aluminium, the central part of which supports the shaft and in the lateral part of which there are arranged a plurality of radial extensions Each 20 extension comprises two cylindrical surface segments inclined with respect to a plane perpendicular to the rotor shaft. The cylindrical surfaces exhibit the same curvature as the blades in their fixing zone. Therefore, when assembled, depending on the zone of the blade which is made to coincide with either of the two cylindrical surfaces of the radial extensions, different 25 blade inclinations are obtained

The present invention enables the manufacture of impellers with any inclination of the blades while always using the same mould components either for the hub of the impeller or the blades, with minimal investment.

5 It is possible to dispose a plurality of blade fixing and centring means on the hub of the impeller.

In the blade fixing zone there may be provided a circular countersunk depression which fits in diameter and coincides in depth with a centring bore formed in the cylindrical surface of the radial extension. The blade is trapped 10 at the base of its circular countersunk depression by a screw, which is screwed into a threaded drill hole situated in the centre of the centring bore.

This allows the blade to be kept tightly connected to the radial extension of the rotor when subject to the centrifugal force which acts on the blade when the impeller is turning.

15 At the base of the radial extensions and perpendicular to the axis of the cylindrical surfaces there may be provided a flat surface which coincides with the flat-surfaced end of the fixing zone of the blade which, together with the centring provided by the countersunk depression in the blade fitted in the centring bore of the radial extension and the centring effect due to the 20 curvatures of the superposed cylindrical surfaces of the radial extension and the fixing zone of the blade,

determines t-hc position thereof on the rotor and prevents any positional uncertainty of the blade with respect to the rotor.

In this way, depending on the angular position of 5 the centring bore in the cylindrical surface of the radial extensions, in which is fitted the circular countersunk depression in the curved surface of the fixing zone of the blade, different inclinations are obtained for the blades and consequently different flows.

10 And furthermore if, instead of forming the hole in one cylindrical surface, it is formed in the opposing cylindrical surface of said radial extension, air flow in the opposite direction is obtained.

With an impeller formed by a plurality of sheet 15 metal blades and a central hub which serves at the same time as the rotor of an external rotor motor as described, the desired objects are achieved, so obtaining an efficient assembly which, in addition, includes other features and advantages which will become clearer from 20 the detailed description of a preferred embodiment

thereof. Said description will henceforth refer to a non-

limiting example, reference being made to the attached drawings, in which: Figure l is a perspective view of an impeller in 25 accordance with the invention, illustrated with only one mounted blade.

Figure 2 is a plan view of one of the sheet metal blades described in the invention.

Figure 3 is an elevational view of the blade of 30 Figure 2, cut through the plane A A. Figure 4 is a perspective view of the hub of the impeller, which in turn is the rotor of an external rotor electric motor, in accordance with the invention.

Figure 5 its a sectional view of the rotor of Figure Figure 6 is an eJevational view of the blade of figure 3 in mounted position on the hub.

5 Figure 7 is a plan view of the hub with the blade of Figure 2 mounted thereon.

And Figure is a front view of a machine for manufacturing an impeller in accordance with the invention. The components which appear in the attached Figures are as follows: (1) impeller hub serving also as the rotor of an external rotor electric motor, (a) radial extensions of hub, (3) magnetic stator of motor, (4) grooves in 15 magnetic stator of motor, (5) external aluminium casing, (6) motor shaft, (7) cylindrical surfaces of radial extensions, (8) cylindrical surface of blade fixing zone, (9) screw for holding assembly tightly together, (10) circular countersunk depression, (]1) centring bore in the cylindrical surface of the radial 20 extension, (12) flat surface, (13) flat-surfaced end of blade fixing zone, (14) radius of curvature of the cylindrical surfaces of the radial extension and of the blade in its fixing zone, (15) angular position a of the centring bore in the curved surface of the radial 25 extension, (16) working zone of the blade, (17) sheet metal blade, (18) lateral surface of rotor (1), (19) blade transition surface, (20) central hole in circular countersunk depression in blade, (21) threaded drill hole, (22) drilling unit, (23) drilling unit, (24) 30 thread-cutting unit, (25) dividing plate, (26a) cylinder, and (26b) cylinder.

The impeller is formed of a plurality of sheet metal blades and a central hub (1), which also serves

5 as the rotor of an external rotor electric motor and which is illustrated by the embodiment shown in the Figures. The Figures show the magnetic stator of the motor (3) with its grooves (4) inside which there is aluminium forming the known squirrel cage, which extends as far as the exterior of the magnetic stator (3) forming the outer casing (5) 10 In the outer casing (5) there is mounted the shaft (6) which, supported in the bearings of the motor, ensures rotation of the rotor around the stator and coaxially therewith. From said outer casing (5) there also protrude a plurality of radial extensions (2), which 15 comprise two curved cylindrical surfaces (7) and a flat surface (12) which is situated at a short distance from the lateral surface (18) of the rotor (1) and is perpendicular to the axis of the cylindrical surfaces (7) of the radial extensions (2). In the zone of the 20 cylindrical surface of the radial extensions (7) there are formed a plurality of centring bores (11) at an angular position (15) which determines the inclination of the blades relative to the hub of the impeller. In the centre of the centring bore (11) and coaxial therewith 25 there is formed a threaded drill hole (21).

On the sheet metal blades (17) it is possible to distinguish the surface of the working zone (16), the cylindrical surface of the fixing zone (8), the transition surface (l9) between the surfaces of the 30 fixing zone and the working zone and a countersunk depression (lo? with a central hole (20).

It should be noted in particular that the radius of curvature (14) of the cylindrical fixing surface (8) of the blade matches the radius of curvature of the

cylindrical surface (7) of the radial extension of the rotor.

When mounting the blades (17) on the rotor (1)7 the circular countersunk depression (10) of the blade is accommodated in the centring bore (11), which it matches in diameter and depth, of the cylindrical surface of 5 the radial extension The flat-surfaced end (13) of the fixing zone of the blade engages with the flat surface (12) of the radial extension (2). By tightening a screw (9) which passes through the opening (20) in the blade and screws into the threaded drill hole (21) in the radial extension, positioning and immobilization of the blade (17) with respect to the rotor (1) are achieved.

10 Where the countersunk depression (10) fits closely within the centring bore (11), little or no relative movement between the blade (10) and radial extension are possible. This avoids the need to provide elements such as notches or projections to limit relative movement.

Figure 8 shows a machine whose function is drilling the centring recess 15 (11) and thread-cutting to produce the threaded bores (21) in the radial extensions (2) of the hub.

This is performed by means of two drilling units (22) and (23) and a thread-cutting unit (24) and a divider (25) to impart rotation to the five radial extensions (2).

20 Pressing the buttons of the control box (not shown) actuates a cylinder (26a) which raises a guard which completely covers the front part of the machine. At the same time as the guard is being raised, another cylinder (26b) descends and in this way may apply pressure to the rotor (1) before starting work.

25 Next, the drilling unit (22) is actuated and produces a through-hole which corresponds to the threaded drill hole (21). On conclusion of this

operation, a dividing plate (25) causes the rotor (1) to turn towards the next position

Subsequently, the dri.1linc3 units (22, 23) are actmat:ed jointly, in order thus to be able to produce a through-}lole [threaded drill hole (21) ] in the new position and a recess [centring recess (11)] where the 5 above mentioned hole was previously formed. On conclusion

of this operation, the dividing plate (25) turns the rotor (1) towards the next position.

C)nce in the new position, the three units, the drilling units (22) and (?3) and the thread-cutting Unit 10 (24), are actuated jointly. On conclusion of the

operation, the dividinc3 plate (25) turns the rotor (1) towards the next position. This operation in which the three units (22, 23, 24) are jointly actuated is repeated twice more. 15 Next, the drilling unit (23) and the thread-cutting unit (24) are actuated jointly. On conclusion of said

operation, the dividing plate (25) turns the rotor (1) towards the final position. In this operation, only the thread-cutting unit (21) is actuated and, once this is 20 concluded, the cylinder (26a) is actuated so that th guard may be opened and the rotor (1) removed. At the same time as the guard is lowered, the cylinder (26b) is actuated to release the pressure on the rotor ( 1).

The machine described is designed to be able to 25 provide the radial extensions (2) of the hub with thirty different inclinations. To achieve this, it is necessary merely to change a pivot in each drilling (22, 23) and threading (24) unit.

30 The materials of the members which make up the impeller assembly described, as well as the shapes, dimensions and other auxiliary features may appropriately be replaced by others which are technically equivalent thereto, as long as the proposed variations do not alter

the essence of the present invention or of the invent ive concept thereof defined in the fold owi ng claims.

Claims

CLAIMS:

1. An impeller assembly comprising a central hub, a plurality of inclined blades, and a plurality of radial extensions, each provided with two cylindrical 5 surfaces, extending from the central hub, at least one of said surfaces being provided with a centring recess and a threaded hole, in which the blades include a cylindrical surface matching the cylindrical surfaces of the radial extensions and a countersunk depression conformed to fit in the centring recess in the radial extensions, which countersunk depression includes a hole 10 for insertion of a screw which passes through the threaded hole in the radial extension to fasten the blade on the hub.

2. An impeller assembly according to claim 1, in which the cylindrical surfaces of the radial extensions are provided with two or more centring bores 15 with their matching threaded holes, and in that the blades have an equal number of countersunk depressions with their respective centred holes.

3. An impeller assembly according to claim 1 or claim 2, in which the blades comprise a flat surface at the ends of their fixing zones which, in the 20 assembled position, matches a flat surface perpendicular to the axis of the cylindrical surfaces of the radial extensions.

4. An impeller assembly according to any one of the preceding claims, wherein the central hub is the rotor of an external rotor electric motor.

5 An impeller assembly substantially as shown in or as described with respect to any of the accompanying drawings.