Centrifugal electric pump assembly

An electric pump assembly includes in sequence: a wet section, an air gap sleeve containing the rotor of an electric motor, and a casing which contains the stator of an electric motor. The electric pump assembly further includes a box, which contains an electronic board- and has a tubular body for the insertion of a plug for access to the wet section. The casing is substantially concentric to the air gap sleeve. The box is constituted by a tray which is closed hermetically by a lid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to and claims the benefit of Italian Patent Application No. 102018000003390, filed on Mar. 9, 2018, the contents of which are herein incorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a centrifugal electric pump assembly. More particularly, the disclosure relates to a centrifugal pump assembly with improved seal. The disclosure is applicable in the field of electric circulating pumps for heating or conditioning systems.

BACKGROUND

Conventional centrifugal electric pump assemblies are composed substantially of a hollow body provided with intake and delivery ducts and containing one or more impellers interleaved by diffusers and keyed on the shaft of an electric motor which is enclosed in a motor casing that isolates it from the pumping liquid.

Centrifugal electric circulating pumps for home systems are normally driven and controlled by an electronic board.

Some of the causes of malfunction or failure problems of this type of electric pump are linked to the penetration of dust and/or liquids, generally water, in the box that contains the electronic board or the electric motor itself.

Dust and water are normally dangerous for the operation of the pump because they can compromise the electrical and mechanical functions of the electric pump.

SUMMARY

The aim of the present disclosure is to provide a centrifugal electric pump assembly that is capable of improving the background art in one or more of the aspects indicated above.

Within this aim, the disclosure provides a centrifugal electric pump assembly that ensures the maximum seal with respect to the penetration of dust and/or liquids.

The disclosure also provides a centrifugal electric pump assembly that prevents the penetration of water and/or dust in the electronic box and in the electric motor.

The disclosure also provides a centrifugal electric pump assembly that is highly reliable, relatively easy to provide and at competitive costs.

These advantages and others which will become better apparent hereinafter are achieved by providing an electric pump assembly comprising in sequence: a wet section, an air gap sleeve, which contains a rotor of an electric motor and a casing which contains a stator of an electric motor, and a box, which contains an electronic board and has a tubular body for the insertion of a plug for access to said wet section, said casing being substantially concentric to said air gap sleeve, characterized in that said box is constituted by a tray which is closed hermetically by a lid.

DETAILED DESCRIPTION OF THE DRAWINGS

With reference toFIGS. 1-7, an electric pump assembly according to the disclosure is shown in cross-section inFIG. 1and is designated by the reference numeral10.

The centrifugal electric pump assembly10comprises, at one end, a box11, which contains an electronic board12for regulating and supplying the electric motor13.

A terminal14for the electric power supply of the electric pump extends from the electronic board12.

The box11is made of plastic material and has a substantially cylindrical extension.

The box11comprises a through central tubular body28with an axis of extension X, which coincides with the axis of extension of the box11.

The tubular body28is adapted for access to the wet section, on the part of the user, after removing a plug29.

The box11is constituted by a tray-like base15, which is closed hermetically by a lid16.

The centrifugal electric pump assembly10comprises, at the other end, a wet section17provided with an intake duct18and a delivery duct19, a volute, and an impeller20, of a known type, which is immersed in said wet section.

The impeller20is keyed on a shaft21of the electric motor13composed of a stator22and a rotor23contained in an air gap sleeve35.

A casing24for accommodating said stator22is interposed between the box11and the wet section17and is substantially concentric with respect to the air gap sleeve35.

The casing24is made of stainless steel.

One of the particularities of the disclosure resides in that there is a first sealing element25between the casing24and the box11.

The first sealing element25is made of plastic material and is co-molded with the box11.

The air gap sleeve35has a first flanged end36which faces the wet section17and a second tubular end37which is opposite with respect to the first one, is connected to the box11and is provided with a threaded body38for the fastening of the plug29for access to the wet section.

The box11faces a first end42of the casing24.

The casing24comprises a second end43which is opposite the first end42and faces partly the wet section17and partly the flanged first end36of the air gap sleeve35.

A second sealing element39, for example made of plastic material and having a T-shaped cross-section, is present between the flanged first end36of the air gap sleeve35, the second end43of the casing24and the wet section17.

A third sealing element40, for example made of plastic material, is present between the second end37of the air gap sleeve35, the first end42of the casing24and the box11.

A fourth sealing element41, such as for example an O-ring, is present between the second end37of the air gap sleeve35and the plug29.

FIG. 2is an enlarged-scale view of a detail of the cross-section ofFIG. 1.

In the region26of the casing24, which corresponds to the region for interfacing with the first sealing element25, there is a surface roughness, not shown in the figures, which is adapted to provide sufficient friction and adhesion with the first sealing element25and avoid the penetration of dust and/or water inside the motor.

In particular, with reference toFIG. 3, the box11is closed hermetically, for example by means of a perimetric laser weld27, along the circular edge of the box, in the region for interfacing between the tray15and the lid16.

With reference toFIG. 4, the box11is provided with at least one through hole30.

The hole30is located on the surface of the box11that faces the casing24, within the perimeter defined by the first sealing element25.

The hole30has the purpose of connecting the box11to the casing24, preventing the onset of overpressures inside the box11, which might cause damage to the electronics and compromise the operation of the entire electric pump.

In a variation, not shown in the figures, the through hole might not be present.

FIG. 5is a general view of the lid16of the box11.

On the lid16there is a portion32that is partially separated from the rest, by means of an opening region34, which is adapted to form the surface of a button for interaction with the electronic board12contained inside the box11.

An adhesive label33is applied to the surface31of the lid16that is opposite with respect to the surface arranged inside the box11and has at least such dimensions as to close the opening region34that is adjacent to the portion32.

The portion32is therefore closed within the volume defined by the box11with the adhesive label33on the outer surface of the box.

In this manner, the adhesive prevents the penetration of dust or water into the box, at the opening region34.

With reference toFIG. 6, an electric pump assembly according to the disclosure, in a different embodiment, is designated by the reference numeral110.

Such centrifugal electric pump assembly110is provided in a manner similar to what has already been described in the preceding embodiment.

In this constructive variation, however, the box111, constituted by a tray115which is closed hermetically with a lid116, comprises a capacitive button119for interaction with the electronic board112.

In particular, the capacitive button119is located between the lid116of the box111and the electronic board112, which is contained therein.

In this case, the lid116of the box111is not provided with opening regions and therefore the box111is closed hermetically without the aid of an adhesive label.

FIG. 6shows the lid116with a view on its face that is external to the box111.

In this constructive variation, all the sealing elements described in the preceding embodiment are present.

In this variation there is no hole on the surface of the box111that faces the casing124, since the box111, which is closed hermetically, is capable of withstanding overpressures even up to 0.3 bar without being damaged and maintaining the seal, which is close to an IP68 level.

In the present description, the abbreviations “IP68” and “IPX5” reference the levels defined by the International Electrotechnical Commission (IEC).

It should be noted that the electric pump assembly110with the box111, in the variation with the box111without holes and openings, substantially has an IP68 seal, which has been verified by means of experimental tests.

This seal is achieved by virtue ofthe presence, between the casing124and the box111, of a first sealing element125;the presence, between the air gap sleeve135, the casing124and the wet section117, of a second sealing element139;the presence, between the air gap sleeve135, the casing124and the box111, of a third sealing element140;the presence, between the air gap sleeve135and the plug129, of a fourth sealing element141;a hermetic closure between the tray115and the lid116of the box111.

It should also be noted that the electric pump assembly in the variation with the box11provided with at least one hole30and an opening region34as described above substantially has an IPX5 seal, which has been verified by means of experimental tests.

This IPX5 seal is achieved by virtue ofthe presence, between the casing24and the box11, of a first sealing element25;the presence, between the air gap sleeve35, the casing24and the wet section17, of a second sealing element39;the presence, between the air gap sleeve35, the casing24and the box11, of a third sealing element40;the presence, between the air gap sleeve35and the plug29, of a fourth sealing element41;a hermetic closure between the tray15and the lid16of the box11and the adhesive label so as to close the opening region34.

In practice it has been found that the disclosure achieves the intended aims and advantages, providing a centrifugal electric pump assembly, of the type comprising a stator accommodation casing and a box, containing an electronic board, which faces one end of said stator accommodation casing, characterized in that it comprises, between said casing and said box, a sealing element, and in that said box is constituted by a tray and a lid which are mutually sealed hermetically.

The disclosure thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may furthermore be replaced with other technically equivalent elements.

In practice, the materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.