ELECTROPUMP

Technical Field

The present invention concerns an electropump.

Background Art

It has been known that in order to transfer a liquid, for example from a reservoir to a tank, suitable pumping members are currently used, such as in particular electropumps. Known electropumps substantially comprise a body shaping a cavity inside which an impeller is fitted. In use, the impeller intakes the water from an inlet opening, for example an axial inlet opening frontally opened on the pump body, and directs it outwards, to a discharge opening, tangential to the same impeller. Moreover, electropumps whose inlet opening is lateral and not axial are also known.

The impeller is driven in rotation by a suitable electric motor member, associated with the body of the pump. The outlet shaft of the motor member is inserted in a housing axially shaped by the impeller hub and coupled with it. In particular, in peripheral pumps the impeller is fitted floating on the motor shaft. In this case, the play between the motor shaft and the impeller must be the smallest in order to reduce, in use, the noise due to the vibrations of the same impeller.

Obviously the coupling of the impeller with the motor shaft is an essential element for the correct functioning of the pump, since it affects the efficacy of the motor to handle the impeller. A faulty coupling can have very damaging consequences on the efficiency of the pump.

For the coupling of the impeller with the motor shaft the use of mechanical transmission members is known, such as for example a key suitable to engage suitable holes made on the motor shaft and in the hub of the impeller. Such solution is not fully effective, both because the key receives cutting stresses which limit the force to be transmitted, and because the stress produced on the motor shaft is not balanced. The use of a key, moreover, implies relatively high costs, since it requires a one by one working of the pieces which perform the coupling and, during the assembling step, an also necessary handling of such key, which evidently constitutes a further element with respect to the members to be coupled.

A different way to carry out such mechanical coupling, known in the considered field, is that of making a longitudinal flattering on the motor shaft, suitable to engage a corresponding flattering made at the axial hole of the impeller. Such solution allows to reduce the production costs, but it does not solve in a satisfying manner the problem of balancing the inflicted stress.

A subsequent evolution of such mechanical coupling has issued the use of two longitudinal flatterings on the motor shaft, parallel and diametrically opposed to each other, so as to distribute in a more suitable way the inflicted stresses. Nevertheless, the points which receive the stresses are not sufficient to produce a correct balance, and, though reduced, the production costs remain relatively high.

Disclosure

[08] The task of the present invention is that of solving the aforementioned drawbacks, devising an electropump which performs in an optimal way the mechanical coupling between the impeller and the motor shaft, in particular assuring a perfect balance of the stress produced by the motor shaft.

[09] Within such task, it is a further scope of the present invention that of providing an electropump in which the mechanical coupling between the impeller and the motor shaft is easy and inexpensive to carry out.

[10] Another scope of the invention is that of providing an electropump in which such coupling between the impeller and the motor shaft has a simple assembling and functional conception, a surely reliable structure as well as a versatile use.

[1 1 ] The cited scopes are attained by the electropump according to claim 1 .

[12] According to the present invention, the coupling portion of the outlet shaft of the pump motor has a grooved profile suitable to be coupled with a corresponding grooved housing of the impeller of the same pump.

[13] Preferably, the grooved profiles of the motor shaft and of the impeller form a splined connection (that is, the so-called "millerighe" connection in Italian language).

Description of Drawings

[14] Details of the invention shall be more apparent from the detailed description of a preferred embodiment of the electropump according to the invention, illustrated for indicative purposes in the attached drawings, wherein:

[15] figure 1 shows an axial section view of the electropump according to the invention;

[16] figure 2 shows a perspective view of the motor member used in the electropump according to the invention;

[17] figure 3 shows a lateral view of the shaft of the motor member;

[18] figure 4 shows a perspective view of the impeller of the electropump according to the invention;

[19] figure 5 shows a top view of the impeller.

Best Mode

[20] With particular reference to such figures, the electropump according to the invention is indicated in its entirety with 1 . In particular, in the illustrated case the electropump 1 is of the so called peripheral or with peripheral channel type.

[21 ] The electropump comprises a body 2 which shapes a cavity inside which an impeller 5 is assembled. The body 2 shapes an axial inlet opening 3 and a discharge opening 4, arranged on a plane transversal with respect to the axis of the electropump, substantially tangential to the impeller 5.

The impeller 5 is suitable to be driven in rotation by a motor member 10 axially constrained, in known manner, to the body 2 of the pump. More particularly, the impeller 5 comprises a wheel 6 provided with a hub 7a which shapes an axial hole 7 for coupling with the outlet shaft 1 1 of the motor member 10, as illustrated hereinafter. The wheel 6 of the impeller has a plurality of radial fins 8, among which respective channels 9 for the passage of the liquid to be pumped are shaped.

The shaft 1 1 of the motor member 10 comprises a coupling portion 12, arranged at one of its ends and suitable to be inserted in the cited axial hole 7 of the hub 7a of the wheel 6. According to the present invention, the coupling portion 12 of the motor shaft 1 1 has a grooved profile 13, to form a splined connection (that is, the so-called "millerighe" connection in Italian language).

More particularly, such grooved profile is shaped through a plurality of teeth 13, angularly distributed on the whole circumference of the same portion 12 of the motor shaft 1 1 (see in particular figures 2 and 3).

In the illustrated example, the teeth 13 have a substantially trapezoid-shaped profile, but it is obviously possible to use a differently shaped toothing.

It is to be observed that the above mentioned grooved profile 13 is advantageously obtained through a single mechanical assemblage, comprising the simultaneous formation of a series of longitudinal grooves 14, suitable to shape the teeth 13 of the grooved profile. The grooved profile 13 of the coupling portion 12 of the motor shaft 1 1 is suitable to be coupled with a correspondent grooved housing 15, provided with an internal toothing, arranged at the axial hole 7 of the wheel 6 of the impeller 5 (see in particular figures 4 and 5). Such grooved housing comprises in particular a plurality of teeth 15 having a profile corresponding to the teeth 13 of the grooved profile of the portion 12 of the motor shaft 1 1 . The motor shaft 1 1 is supported in rotation by known bearing members 16.

The functioning of the electropump is easy to understand through the preceding description.

The coupling portion 12 with grooved profile 13 of the motor shaft 1 1 is inserted in the corresponding housing 7 with grooved profile 15 and with internal toothing shaped on the hub 7a of the wheel 6 of the impeller 5.

Therefore, during the motion transmission to such impeller 5, the stress of the motor member 10 is perfectly balanced along the whole circumference of the coupling between the motor shaft 1 1 and the wheel 6 of the impeller. This determines, moreover, a possible increase of the force which can be transmitted by the motor. [33] A feature of the invention consists in that the making of the coupling is particularly simple and relatively inexpensive. The cited grooved profiles can be, in fact, realized through a single mechanical assemblage, by means of suitable apparatuses of known type.

[34] In practice, the embodiment of the invention, the materials used, as well as the shape and dimensions, may vary depending on the requirements.

[35] Should the technical characteristics mentioned in each claim be followed by reference signs, such reference signs were included strictly with the aim of enhancing the understanding the claims and hence they shall not be deemed restrictive in any manner whatsoever on the scope of each element identified for exemplifying purposes by such reference signs.