WO2010025959A2

WO2010025959A2 - Unidirectional synchronous electric pump, particularly for electric household appliances

Info

Publication number: WO2010025959A2
Application number: PCT/EP2009/006492
Authority: WO
Inventors: Giorgio Colmanet
Original assignee: Askoll P&C S.R.L.
Priority date: 2008-09-08
Filing date: 2009-09-08
Publication date: 2010-03-11
Also published as: ITTO20080659A1; IT1396749B1; WO2010025959A3

Abstract

The pump ( 1) comprises an envelope (2) wherein the following are defined: a pumping chamber (3a) and a driving chamber (3b); a synchronous electric motor (4) with a rotor (6) rotatable in the driving chamber (3b) and whose shaft (8) extends in the pumping chamber (3a); a bladed impeller (9) having a central body (10) which can be coupled in rotation with the shaft (8); a rotatable hub (12) integral with a rotating part (12; 6) of the pump (1), and a control rotor or counter-rotor (22), rotatable around the hub (12) around an eccentric axis (B-B), parallel and distanced from that (A-A) of the shaft (8). The hub (12) and the control rotor (22) have respective formations (21; 26) subject to engaging one with the other when the motor (4) starts in a predetermined direction to achieve the driving in rotation of the control rotor (22) in a first configuration or relative arrangement wherein the control rotor (22) does not interfere with the rotation. When the motor (4) starts in the opposite direction, the control rotor (22) rotates in relation to the hub (12) around the eccentric axis (B-B) assuming an arrangement wherein it projects progressively in relation to the axis (A-A) of the shaft (8) of the motor (4), until it interferes with a wall (30; 130) of the envelope (2) and blocks the rotation of the rotor (6), then allowing the subsequent inversion of the rotation of the rotor (6) and of the bladed impeller (9).

Description

Title: "Unidirectional synchronous electric pump, particularly for electric household appliances"

DESCRIPTION Technical field of the invention The present invention relates to a centrifugal pump, particularly for use in electric household appliances.

More specifically the object of the invention is a centrifugal pump of the type comprising: a supporting envelope wherein a pumping chamber and a driving chamber are defined; an electric a.c. synchronous motor, including a permanent magnet rotor mounted rotatably in the driving chamber and whose shaft extends rotatably in the pumping chamber; and a bladed impeller having a central body which can be coupled for rotation with one end of said shaft with an angular play suitable for allowing start of the rotation of the motor.

Prior Art

Centrifugal pumps with synchronous electric motor of this type are described for example in the European patent application EP0207430 and in the European patent EP 139664 IBl.

These centrifugal pumps with synchronous electric motor are not in general of the unidirectional type, i.e. subject to rotating in a same predetermined direction. Consequently the outlet conduit of the pumping chamber is not made tangential but instead radial; moreover the blades of the impeller are in general flat and radial. This entails a loss of efficiency.

Solutions have already been proposed for making a synchronous electric pump unidirectional. One solution is described for example in the international patent application WO2005/ 106253 in the name of the same Applicant. An object of the present invention is to propose a new centrifugal pump with synchronous electric motor, with unidirectional functioning.

Summary of the Invention

These and other objects are achieved according to the invention with a pump of the type defined initially, characterised in that it comprises moreover

a rotatable hub integral with a rotating part of the pump, and

a control rotor or counter-rotor, mounted rotatably in relation to hub (12) within said envelope around an eccentric axis which is parallel to and spaced from the axis of said shaft; the hub and the control rotor having respective formations subject to engaging one with the other when the motor starts to rotate in a predetermined direction, to achieve the driving of the control rotor in a first configuration or relative arrangement wherein said control rotor does not interfere with the rotation; the arrangement being such that, when the motor starts to rotate in the direction opposite to said predetermined direction, the control rotor rotates relatively to the hub around said eccentric axis, assuming a configuration or relative arrangement wherein it projects radially to a progressively increasing extent in relation to the axis of the motor, until it interferes with a wall of said envelope and blocks the rotation of the rotor in said opposite direction, allowing the subsequent inversion of the rotation of the rotor and of said bladed impeller.

In a first embodiment the abovementioned hub is integral in rotation with the bladed impeller, while in a second embodiment the hub is integral in rotation with the rotor.

Further features and advantages of the invention will be made clearer from the following detailed description, given purely by way of a non- limiting example, with reference to the accompanying drawings, in which:

Brief description of the drawings Figure 1 is a partial perspective view of a centrifugal pump according to the present invention;

Figure 2 is a partially sectioned view along line H-II of Figure 1;

Figures 3 and 4 are an axially sectioned view and, respectively, a view from above of a hub of the pump according to the previous drawings;

Figures 5 and 6 are an axially sectioned view and, respectively, a plan view from above of a control rotor or counter-rotor of the pump according to the previous drawings;

Figures 7 to 9 are three partial plan views from above of the pump according to the previous drawings, in three different working configurations;

Figure 10 is a partial axially sectioned view of another pump according to the invention;

Figure 11 is a plan view of the rotor of the pump of Figure 10; Figure 12 is a sectioned view of the control rotor or counter-rotor for the pump according to Figure 10;

Figure 13 is a blown-up partial perspective view of the pump according to Figure 10, and

Figures 14 and 15 are two partial cross-sectioned views of the pump according to Figure 10 in two different working conditions.

Detailed description

In Figure 1 a centrifugal pump according to the invention is denoted overall by 1.

In a manner in itself known the pump 1 comprises a supporting envelope 2 including a shaped body 2 a and a spiral (not illustrated) coupled one with the other in such a way as to define a work chamber or pumping chamber 3a.

The supporting envelope 2 comprises moreover an essentially tubular part - A -

2b, wherein a driving chamber 3b is defined.

The pump 1 comprises a single-phase synchronous electric motor, powered with an alternating current, denoted overall by 4. In a manner known per se the motor 4 comprises a stator 5, stationary in relation to the body 2, and a permanent magnet rotor 6, mounted rotatably in the chamber 3b of the part 2b of the body 2, and illustrated by a dotted line in Figure 1. In a manner equally known in itself, the stator 5 holds at least one winding, such as that denoted by 7 in Figure 1.

The rotor 6 of the motor 4 has a central shaft, denoted by 8 in Figure 2. The upper end 8a of this shaft 8 extends rotatably in the pumping chamber 3a, where it is coupled with a bladed impeller denoted overall by 9.

In the embodiment illustrated the bladed impeller 9 comprises a hollow central body 10, wherefrom a plurality of shaped blades 11 extend externally. This impeller is coaxial with the axis A-A (Figure 2) of the shaft 8 of the electric motor 4.

In the central body 10 of the impeller 9 a chamber is defined wherein the upper end 8a of the shaft 8 extends. Between this end of the shaft 8 and the central body 10 of the impeller 9 a rotation coupling is provided with angular play, for example of the type described in the European patent EP1396641B1, to allow rotation starting of the electric motor 4. The means for achieving this coupling are in themselves known and will not therefore be described here further.

Referring in particular to Figures 2 to 4, a hub is overall denoted with 12, for example in a metal material, attached to the central body 10 of the bladed impeller 9.

In the embodiment illustrated the hub 12 has an axial passage 13 wherein the end 8a of the shaft 8 of the motor extends rotatably. Around this passage the hub 12 has above an essentially cylindrical formation 14, which engages in the hollow central body 10 of the bladed impeller 9.

Below the formation 14, the hub 12 has a second essentially cylindrical formation denoted by 15. In the mounted condition (Figure 2) the passage 13 and the cylindrical formation 14 of the hub 12 are coaxial with the axis A-A of the shaft 8 of the electric motor 4. The axis of the cylindrical formation 15 of the hub 12, denoted by B-B in Figure 2, is parallel and eccentric in relation to the axis A-A.

Below the cylindrical portion 15 the hub 12 has a sort of shaped support flange denoted by 16.

Below the flange 16, around the lower end of the passage 13, the hub 12 has a lower tubular appendage 17, around which a torsion spring 18 is arranged. The end branches or prongs 18a and 18b of this spring abut against respective stop pegs 19 and 20 (see in particular Figure 4) which extend from the lower face of a radially projecting portion 16a of the flange 16. In the condition shown in Figure 4, the spring 18 is preferably in a preloaded condition, in the sense that its branches 18a and 18b are maintained elastically apart.

The branch 18a of the spring 18 is radially more extended in relation to the other branch 18b, and in particular it extends radially beyond the peripheral edge of the portion 16a of the flange 16.

An engaging member 21, preferably in an elastomeric material, is moreover attached to the lower face of the portion 16a of said flange. As can be seen in Figure 4, in the embodiment illustrated the engaging member 21 projects radially beyond the edge of the portion 16a of the flange 16.

The pump 1 comprises moreover a control rotor or counter-rotor, denoted by 22 (see in particular Figures 1, 2, 5 and 6).

In the embodiment illustrated the control rotor 22 has an essentially disc- like shape, with a raised circumferential edge 23 at one of its main faces.

In the wall of the control rotor 22 an eccentric circular aperture 24 is formed, whose diameter corresponds essentially to the diameter of the cylindrical portion 15 of the hub 12. As can be seen in particular in Figure 2, in the mounted condition the control rotor 22 is arranged with its aperture 24 around the abovementioned cylindrical formation 15 of the hub 12, and is rotatable idly in relation to this hub, around the eccentric axis B-B.

Referring to Figure 6, the control rotor 22 has further apertures 25 for purposes of balancing. From the lower face of the control rotor 22 a peg denoted by 26 in Figures 5 and 6 extends. This peg is intended to co-operate, as will be described in greater detail herein below, with an engaging member 21 of the hub 12 and with the branch 18a of the spring 18.

In the embodiment illustrated, the control rotor 22 is provided externally with an elastic covering 27, made for example with a so-called O-ring or with an over-moulded element. The function of this covering will be made clearer herein below.

Referring to Figure 2, in the mounted condition the control rotor 22 rests on the flange 16, 16a of the hub 12 and, as already mentioned, is rotatable idly around the cylindrical portion 15 of this hub, and therefore around the eccentric axis B-B. As can be seen in Figure 7, the peg 26 projecting below from the control rotor 22 is at rest within an angle (in relation to the axis A-A) between the engaging member 21 and the radially projecting end 18a of the spring 18. The pump described above is made in such a way that during functioning its bladed impeller 9 rotates in a predetermined direction, more particularly anticlockwise for those who observe Figures 1 and 7.

This pump operates in fact in the following way.

Starting for example from the condition of Figure 7, if the electric motor 4 starts in the "right" direction, therefore anticlockwise, the shaft 8, after uptake of the possible angular play between its end 8a and the body 10 of the bladed impeller 9, drives the latter and the hub 12 in rotation. The hub 12 then drives in rotation the control rotor 22, following engaging of its member 21 with the peg 26 of the latter. The arrangement is such that, as shown in Figure 7, in the condition described above the control rotor 22 assumes, in relation to the hub 12, a configuration or relative arrangement wherein this impeller 22 extends radially at a distance from the lateral wall 30 (Figure 1 and Figures 7 to 9) of the pumping chamber 3a.

If instead at actuation the synchronous electric motor 4 starts in the "wrong" direction, i.e. clockwise in the example described above, then starting from an initial configuration of the type illustrated in Figure 7 the situation evolves according to the sequence partially illustrated in Figures 8 and 9.

More particularly, in this case too the shaft 8 of the rotor, after possible uptake of the angular play in relation to the central body 10_; drives in rotation the bladed impeller 9 and the hub 12 in the "wrong" direction. The control rotor 22, which is idle in relation to the hub 12, would tend to remain stationary due to the effect of its mechanical inertia and the friction with the water in the pumping chamber. In actual fact the rotor 22 also starts to rotate, in the "wrong" direction, however at a lower speed in relation to that of the hub 12. Relative rotation is therefore created between the control rotor 22 and the hub 12, around the axis B-B.

At a certain point the radially projecting portion 18a of the spring 18 engages (Figure 8) the lower ridge 26 of the control rotor 22, and the spring 18 is loaded. Due to the effect of the relative rotation between the control rotor 22 and the hub 12, this rotor assumes a configuration or relative arrangement wherein it projects radially to a progressively increasing extent in relation to the axis A-A of the shaft 8 of the motor, until, as shown in Figure 9, it impacts against a portion of the lateral wall 30 of the pumping chamber and blocks the rotation of the bladed impeller 9 and of the motor in the "wrong" direction, allowing however the subsequent inversion of the rotation of the rotor and of the bladed impeller, which restart and then proceed in the "right" direction of rotation.

The peripheral elastic covering 27 of the control rotor 22, and the action of the spring 18, are such as to facilitate the "rebound" of the control rotor 22 after the impact with the lateral wall 30 of the pumping chamber.

The spring 18 is moreover useful for preventing, during the manipulations and movements of the pump 1 or of the electric household appliance wherein it is incorporated, the control rotor 22 from "sticking" against the lateral wall of the pumping chamber, making subsequent starting of the pump difficult if not impossible.

Figures 10 to 15 illustrate another embodiment of a pump 1 according to the invention. In these figures parts and elements (even if not necessarily identical) corresponding to those already described in relation to Figures 1-9 have been attributed again the same reference numerals already used previously.

In the embodiment according to Figures 10 to 15 the pump 1 comprises (see in particular Figure 3) a cylindrical hub 12, integral in rotation with the rotor 6 of the synchronous electric motor 4. The hub 12 is for example over-moulded on the rotor 6, integrally with an end head 6a of the latter.

The hub 12 is disaligned in relation to the axis A-A of the shaft 8 of the rotor 6: the axis of this hub, denoted here too by B-B, is distanced and parallel to the axis A-A,

In the pump 1 according to Figure 10 onwards there is also a control rotor or counter-rotor, this time again denoted by 22 (se in particular Figures 12 and 13). In the embodiment illustrated in the drawings the control rotor 22 is essentially shaped like a disc having a diameter corresponding to that of the rotor 6.

The control rotor 22 has an eccentric circular aperture 24 wherein the hub 12, which is integral with the rotor 6, engages rotatably.

From the face of the control rotor 22 which is turned to the head 6a of the rotor 6 a projecting peg 26 extends, which engages in a recess 6b with an arched slot shape of the head 6a.

The recess 6b extends essentially along a circumference arc centred on the axis B-B of the hub 12. In this recess a spring 40 (Figures 11, 14 and 15) can be optionally placed.

At rest, the control rotor 22 is, in relation to the rotor 6, in the position illustrated in Figures 10 and 14. More particularly its ridge 26 engages an end of the slot 6b of the rotor 6, as can be seen in Figure 14. When the electric motor 4 is actuated, it may, in a random manner, start clockwise or anticlockwise.

The pump according to Figure 10 onwards is also made in such a way that its bladed impeller 9 rotates operatively in a predetermined direction which in the example illustrated is anticlockwise.

Starting from the condition of Figures 10 and 14, if the rotor 6 of the motor starts in the required direction, therefore anticlockwise, by means of the peg 26, which abuts against the "rear" end of the slot 6b, the control rotor 22 is driven in rotation integrally with the rotor 6. The relative position of this control rotor 22 in relation to the rotor 6 does not change, and the rotor 6 can then drive in rotation the bladed impeller 9 in the required direction.

If instead on actuation of the motor 4 its rotor 6 starts in the "wrong" direction, i.e. clockwise in the example illustrated, between the rotor 6 and the control rotor 22 a progressive angular displacement occurs around the axis B-B, enabled by the sliding of the peg 26 in the slot 6b. Due to this relative rotation the control rotor 22 projects radially to a progressively increasing extent in relation to the axis A-A of the shaft 8, until, as shown in Figure 15, it impacts against a portion of the lateral wall 130 of the driving chamber 3b and blocks the rotation of the rotor 6 in the wrong direction, allowing however the subsequent inversion of the rotation of the rotor, which then restarts and then continues in the "right" direction, driving the bladed impeller 9.

Also in the pump according to Figures 10- 15 the control rotor 22 can be provided with an elastic covering in the area intended to impact against the wall 130 of the chamber 3b. Moreover it can likewise be provided with further apertures or recesses for lightening and balancing.

Naturally, without prejudice to the principle of the invention, the embodiments and details may be widely varied in relation to what has been described and illustrated purely by way of a non-limiting example without thereby departing from the sphere of the invention as defined in the annexed claims.

Claims

1. A centrifugal pump (1) particularly for electric household appliances, comprising

a supporting envelope (2) in which a pumping chamber (3a) and a driving chamber (3b) are defined,

an electric a.c. synchronous motor (4) including a permanent magnet rotor (6) mounted rotatably in the driving chamber (3b) and having a shaft (8) which extends so as to be rotatable in the pumping chamber (3a); and

a bladed impeller (9) with a central body (10) which is designed to be coupled for rotation with one end (8a) of said shaft (8) with an angular play designed to allow the start of the rotation of the motor (4);

the pump (1) being characterized in that it further includes:

a rotatable hub (12) which is fixed to a rotating part (12; 6) of the pump (1), and

a control rotor or counter-rotor (22), mounted rotatably around said hub (12) within said envelope (2) around an eccentric axis (B-B) which is parallel to and spaced from the axis (A-A) of said shaft (8);

the hub (12) and the control rotor (22) having

respective formations (21; 26) which are capable of engaging with each other when the motor (4) starts rotating in a predetermined direction, to cause the rotation of the control rotor (22), in a first configuration or relative arrangement wherein the control rotor (22) does not interfere with said rotation;

the arrangement being such that when the motor (4) starts rotating in the direction opposite said predetermined direction, the control rotor (22) rotates with respect to the hub ( 12) about said eccentric axis (B-B) assuming a configuration or a relative arrangement wherein it increasingly protrudes radially with respect to the axis (A-A) of the shaft (8) of the motor (4), until it interferes with a wall (30; 130) of said envelope (2) and stops the rotation of the rotor (6) in said opposite direction, permitting thereafter the subsequent inversion of the direction of rotation of the rotor (6) and of said bladed impeller (9).

2. A centrifugal pump according to claim 1, wherein said rotating member (12; 6) of the pump (1) carries resilient means (18) capable of interacting with the control rotor (22) when the motor (4) causes the bladed impeller (9) to rotate in the direction opposite said predetermined direction.

3. A centrifugal pump according to claim 1 or claim 2, in which the hub (12) is fixed for rotation with the bladed impeller (9).

4. A centrifugal pump according to claim 1 or claim 2, in which the hub (12) is fixed for rotation with the rotor (6) of the electric motor (4).