Patent Publication Number: US-11035365-B2

Title: Centrifugal electric pump assembly

Description:
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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further characteristics and advantages of the disclosure will become better apparent from the description of a preferred but not exclusive embodiment of the electric pump assembly according to the disclosure, illustrated by way of non-limiting example in the accompanying drawings, wherein: 
         FIG. 1  is a sectional view of the electric pump assembly according to the disclosure in a first embodiment; 
         FIG. 2  is a sectional view of a detail of the electric pump assembly of  FIG. 1 ; 
         FIG. 3  is sectional view of another detail of the electric pump assembly of  FIG. 1 ; 
         FIG. 4  is a general perspective view of an element of the electric pump assembly of  FIG. 1 ; 
         FIG. 5  is a general view of some components of the electric pump assembly of  FIG. 1 ; 
         FIG. 6  is a sectional view of the electric pump assembly according to the disclosure in a second embodiment; and 
         FIG. 7  is a general view of some components of the electric pump assembly of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     With reference to  FIGS. 1-7 , an electric pump assembly according to the disclosure is shown in cross-section in  FIG. 1  and is designated by the reference numeral  10 . 
     The centrifugal electric pump assembly  10  comprises, at one end, a box  11 , which contains an electronic board  12  for regulating and supplying the electric motor  13 . 
     A terminal  14  for the electric power supply of the electric pump extends from the electronic board  12 . 
     The box  11  is made of plastic material and has a substantially cylindrical extension. 
     The box  11  comprises a through central tubular body  28  with an axis of extension X, which coincides with the axis of extension of the box  11 . 
     The tubular body  28  is adapted for access to the wet section, on the part of the user, after removing a plug  29 . 
     The box  11  is constituted by a tray-like base  15 , which is closed hermetically by a lid  16 . 
     The centrifugal electric pump assembly  10  comprises, at the other end, a wet section  17  provided with an intake duct  18  and a delivery duct  19 , a volute, and an impeller  20 , of a known type, which is immersed in said wet section. 
     The impeller  20  is keyed on a shaft  21  of the electric motor  13  composed of a stator  22  and a rotor  23  contained in an air gap sleeve  35 . 
     A casing  24  for accommodating said stator  22  is interposed between the box  11  and the wet section  17  and is substantially concentric with respect to the air gap sleeve  35 . 
     The casing  24  is made of stainless steel. 
     One of the particularities of the disclosure resides in that there is a first sealing element  25  between the casing  24  and the box  11 . 
     The first sealing element  25  is made of plastic material and is co-molded with the box  11 . 
     The air gap sleeve  35  has a first flanged end  36  which faces the wet section  17  and a second tubular end  37  which is opposite with respect to the first one, is connected to the box  11  and is provided with a threaded body  38  for the fastening of the plug  29  for access to the wet section. 
     The box  11  faces a first end  42  of the casing  24 . 
     The casing  24  comprises a second end  43  which is opposite the first end  42  and faces partly the wet section  17  and partly the flanged first end  36  of the air gap sleeve  35 . 
     A second sealing element  39 , for example made of plastic material and having a T-shaped cross-section, is present between the flanged first end  36  of the air gap sleeve  35 , the second end  43  of the casing  24  and the wet section  17 . 
     A third sealing element  40 , for example made of plastic material, is present between the second end  37  of the air gap sleeve  35 , the first end  42  of the casing  24  and the box  11 . 
     A fourth sealing element  41 , such as for example an O-ring, is present between the second end  37  of the air gap sleeve  35  and the plug  29 . 
       FIG. 2  is an enlarged-scale view of a detail of the cross-section of  FIG. 1 . 
     In the region  26  of the casing  24 , which corresponds to the region for interfacing with the first sealing element  25 , there is a surface roughness, not shown in the figures, which is adapted to provide sufficient friction and adhesion with the first sealing element  25  and avoid the penetration of dust and/or water inside the motor. 
     In particular, with reference to  FIG. 3 , the box  11  is closed hermetically, for example by means of a perimetric laser weld  27 , along the circular edge of the box, in the region for interfacing between the tray  15  and the lid  16 . 
     With reference to  FIG. 4 , the box  11  is provided with at least one through hole  30 . 
     The hole  30  is located on the surface of the box  11  that faces the casing  24 , within the perimeter defined by the first sealing element  25 . 
     The hole  30  has the purpose of connecting the box  11  to the casing  24 , preventing the onset of overpressures inside the box  11 , 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. 5  is a general view of the lid  16  of the box  11 . 
     On the lid  16  there is a portion  32  that is partially separated from the rest, by means of an opening region  34 , which is adapted to form the surface of a button for interaction with the electronic board  12  contained inside the box  11 . 
     An adhesive label  33  is applied to the surface  31  of the lid  16  that is opposite with respect to the surface arranged inside the box  11  and has at least such dimensions as to close the opening region  34  that is adjacent to the portion  32 . 
     The portion  32  is therefore closed within the volume defined by the box  11  with the adhesive label  33  on the outer surface of the box. 
     In this manner, the adhesive prevents the penetration of dust or water into the box, at the opening region  34 . 
     With reference to  FIG. 6 , an electric pump assembly according to the disclosure, in a different embodiment, is designated by the reference numeral  110 . 
     Such centrifugal electric pump assembly  110  is provided in a manner similar to what has already been described in the preceding embodiment. 
     In this constructive variation, however, the box  111 , constituted by a tray  115  which is closed hermetically with a lid  116 , comprises a capacitive button  119  for interaction with the electronic board  112 . 
     In particular, the capacitive button  119  is located between the lid  116  of the box  111  and the electronic board  112 , which is contained therein. 
     In this case, the lid  116  of the box  111  is not provided with opening regions and therefore the box  111  is closed hermetically without the aid of an adhesive label. 
       FIG. 6  shows the lid  116  with a view on its face that is external to the box  111 . 
     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 box  111  that faces the casing  124 , since the box  111 , 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 assembly  110  with the box  111 , in the variation with the box  111  without holes and openings, substantially has an IP68 seal, which has been verified by means of experimental tests. 
     This seal is achieved by virtue of
         the presence, between the casing  124  and the box  111 , of a first sealing element  125 ;   the presence, between the air gap sleeve  135 , the casing  124  and the wet section  117 , of a second sealing element  139 ;   the presence, between the air gap sleeve  135 , the casing  124  and the box  111 , of a third sealing element  140 ;   the presence, between the air gap sleeve  135  and the plug  129 , of a fourth sealing element  141 ;   a hermetic closure between the tray  115  and the lid  116  of the box  111 .       

     It should also be noted that the electric pump assembly in the variation with the box  11  provided with at least one hole  30  and an opening region  34  as described above substantially has an IPX5 seal, which has been verified by means of experimental tests. 
     This IPX5 seal is achieved by virtue of
         the presence, between the casing  24  and the box  11 , of a first sealing element  25 ;   the presence, between the air gap sleeve  35 , the casing  24  and the wet section  17 , of a second sealing element  39 ;   the presence, between the air gap sleeve  35 , the casing  24  and the box  11 , of a third sealing element  40 ;   the presence, between the air gap sleeve  35  and the plug  29 , of a fourth sealing element  41 ;   a hermetic closure between the tray  15  and the lid  16  of the box  11  and the adhesive label so as to close the opening region  34 .       

     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.