Patent Publication Number: US-8989566-B2

Title: Heating pump

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This non-provisional patent application claims priority under 35 U.S.C. §119(a) from Patent Application No. 201110333673.5 filed in The People&#39;s Republic of China on Oct. 28, 2011. 
     FIELD OF THE INVENTION 
     This invention relates to heating pumps and particularly, to a heating pump having high heating efficiency. 
     BACKGROUND OF THE INVENTION 
     A heating pump is a pump with a build-in heater to heat liquid being pumped. An existing heating pump includes a housing, an impeller received in the housing, a motor to drive the impeller and a heater fixed to an interior surface of the housing. In operation, liquid entering the housing via an inlet, is forced against the heater by the impeller and finally expelled through an outlet of the housing. In this process, the liquid is heated as it contacts the heater and therefore leaves the pump with an elevated temperature. However, only the heat from the inner surface of the heating tube is absorbed by the liquid, the heat radiating from the outer surface is wasted. This results in a heating pump with a low heating efficiency. 
     The present invention aims to provide a new heating pump which can solve or at least mitigate the above mentioned problem. 
     SUMMARY OF THE INVENTION 
     Accordingly, in one aspect thereof, the present invention provides a heating pump, comprising: a motor; a housing fixed to the motor, the housing comprising an axially arranged intake tube and a discharge port arranged at the periphery thereof; an impeller driven by the motor and received in the housing, the impeller comprising an axially arranged inlet communicating with the intake tube and a plurality of radially arranged, circumferentially spaced, outlets; and a tubular heating member fixed in the housing; a first passage surrounded by the heating member, the outlets communicating with the discharge port via the first passage; and a second passage formed between a radially outer surface of the heating member and a radially inner surface of the housing and communicating with the first passage. 
     Preferably, the first passage is formed between a radially outer surface of the intake tube and a radially inner surface of the heating member. 
     Preferably, the housing further comprises a plurality of guide blades disposed in the first passage to guide liquid to flow through the first passage along a spiral path. 
     Preferably, the housing further comprises an end surface at an axial end thereof remote from the motor and a recess formed in the end surface, and wherein the intake tube is received in the recess, and the first passage is formed between a radially inner surface of the heating member and a radially outer surface of the end surface that surrounds the recess. 
     Preferably, an inner diameter of the intake tube gradually becomes smaller in a direction towards the impeller. 
     Preferably, an inner end of the intake tube facing the impeller is contoured and a part of the impeller extends into the inner end of the intake tube. 
     Preferably, the outlets further communicate with the discharge port via the second passage. 
     Preferably, the housing further comprises a spiral rib protruding from an inner surface of the housing for guiding liquid to flow through the second passage along a spiral path. 
     Preferably, the housing further comprises an end ring partially sealing an axial end of the second passage remote from the motor, and a discharge aperture formed in the end ring, the second passage communicating with the discharge port via the discharge aperture. 
     Preferably, the housing further comprises a substantially cylindrical lateral wall, wherein the end ring extends radially inwards from an axial end of the lateral wall; the heating pump further comprises a circular plate fixed between the motor and the impeller and seals the other axial end of the lateral wall. 
     Preferably, the heating member is fixed to the end ring, and a gap is formed between the heating member and the circular plate in the axial direction; the first passage communicating with the second passage via the gap. 
     Preferably, the circular plate comprises an annular wall protruding towards the end ring, the annular wall comprises a first ring groove formed in a surface thereof that faces towards the end ring and a plurality of openings axially spaced from the first ring groove; the end ring comprising a second ring groove, the discharge aperture is arranged between the second ring groove and the lateral wall; two axial ends of the heating member are respectively received in the first and second ring grooves; and the first passage communicates with the second passage via the openings. 
     Preferably, the heating member comprises a metal tube and at least one resistor disposed within a wall of the metal tube. 
     Preferably, the heating member comprises a metal tube, at least one resistor running circumferentially on a radially outer surface of the metal tube, and a sealing element sealing the at least one resistor in a liquid-tight manner. 
     Preferably, the sealing element comprises a sealing tube that covers the radially outer surface of the metal tube and two axial ends that sealingly contact two axial ends of the metal tube. 
     Alternatively, the housing further comprises a substantially cylindrical lateral wall that is substantially parallel with an axis of the motor, the lateral wall comprises a through hole; the sealing element further comprises a extending ring extending from the sealing tube and extending through the through hole, and ends of the at least one resistor are exposed in the extending ring. 
     Preferably, the housing further comprises a fixing ring extending from an edge of the through hole, the extending ring is sealingly connected to the fixing ring. 
     Preferably, a connector is connected to the ends of the at least one resistor, and the connector is received in the extending ring and configured for connecting to a power source. 
     According to a second aspect thereof, the present invention provides a heating pump, comprising: a motor defining an axis of the pump; a housing fixed to the motor, the housing comprising: a cylindrical lateral wall extending coaxially and having an open first axial end and a closed second axial end, the first axial end disposed adjacent the motor, an axially arranged intake tube passing through the middle of the closed second axial end and a discharge port arranged at the periphery thereof; an impeller driven by the motor and received in the housing, the impeller comprising an axially arranged inlet communicating with the intake tube and a plurality of radially arranged outlets; a tubular heating member fixed in the housing; a first passage formed between a radially outer surface of the intake tube and a radially inner surface of the heating member; and a second passage formed between a radially outer surface of the heating member and a radially inner surface of the housing, wherein the outlets communicate with the discharge port via the first and second passages. 
     According to a third aspect thereof, the present invention provides a heating pump, comprising: a motor; a housing fixed to the motor, the housing comprising an end surface at an axial end thereof that is remote from the motor, a recess formed in the end surface, an axially arranged intake tube received in the recess, and a discharge port arranged at the periphery thereof; an impeller driven by the motor and received in the housing, the impeller comprising an axially arranged inlet communicating with the intake tube and a plurality of radially arranged outlets radially surrounding the inlet; and a tubular heating member fixed in the housing; a first passage formed between a radially inner surface of the heating member and a radially outer surface of the end surface that surrounds the recess; and a second passage formed between a radially outer surface of the heating member and a radially inner surface of the housing, wherein the outlets communicate with the discharge port via the first and second passages. 
     In embodiments of the present invention, as both sides of the tubular heating member contact liquid passing through the housing, heat from both radial sides of the heating member is absorbed. Compared to a heating pump that has only the radially inner side in contact with the liquid, the heating pump of the present invention has a higher heating efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, by way of example only, with reference to figures of the accompanying drawings. In the figures, identical structures, elements or parts that appear in more than one figure are generally labeled with a same reference numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are generally chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed below. 
         FIG. 1  illustrates a heating pump according to a preferred embodiment of the present invention; 
         FIG. 2  is a partially exploded view of the heating pump of  FIG. 1 ; 
         FIG. 3  illustrates a partial longitudinal section through the heating pump of  FIG. 1 ; 
         FIG. 4  illustrates a base of the heating pump of  FIG. 1 ; 
         FIG. 5  illustrates a housing of the heating pump of  FIG. 1 ; 
         FIG. 6  is a partial view of a longitudinal section through a heating pump according to a second embodiment of the present invention, showing a heating member, a housing, and a circular plate; 
         FIG. 7  is a longitudinal sectional view of a heating pump without a motor, according to a third embodiment of the present invention; and 
         FIG. 8  illustrates a housing of the heating pump of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring firstly to  FIGS. 1 to 5 , a heating pump  10 , according to the preferred embodiment of the present invention, includes a base  20 , a motor  30 , an impeller  40 , a heating member  50 , a housing  60 , and a connector  80 . 
     The base  20 , as more clearly shown in  FIG. 4 , includes a circular plate  21  and an annular wall  22 . The circular plate  21  has a shaft hole  23  at the center thereof. The annular wall  22  extends axially from the circular plate  21  at a location near the edge of the circular plate  21  and is generally coaxial with the shaft hole. The annular wall  22  has a first ring groove  24  formed in the top surface of the annular wall. The annular wall  22  also defines a number of openings  25  that pass radially through the annular wall. Preferably, the openings  25  are spaced apart from the first ring groove  24  in the axial direction of the circular plate  21 , so that the openings  25  do not communicate with the first ring groove  24 . The motor  30  is detachably connected to the base  20 , with the shaft thereof passing through the shaft hole  23  and a liquid-tight sealing ring (not shown) sealing the shaft to the base. It should be understood that the base  20  can be integrally formed with an end cap of the motor  30 . In this case, the housing  60  can be directly connected to the motor  30 . Also, it is possible for the openings  25  to completely separate the annular wall into a number of sections such that the annular wall  22  is intermittent. 
     The impeller  40  is fixed to the shaft of the motor  30  with the annular wall  22  radially surrounding the impeller. The impeller  40  is of the centrifugal type, including a lower cover  41 , a number of blades  42  extending from the cover  41 , an inlet  43  formed by the radially inner ends of the blades, and a number of outlets  44  located at the periphery thereof. The blades  42  are curved in the radial direction of the impeller  40 . The inlet  43  communicates with the spaces between the radially inner ends of adjacent blades  42 . Each outlet  44  is formed between the radially outer ends of adjacent blades  42 . As shown, the diameter of the inlet  43  gradually becomes smaller in a direction towards the motor, due to the radially inner ends of the blades being axially inclined. 
     The heating member  50  includes a metal tube  51 , a number of thick-film resistors  52 , and a sealing element  53 . The thick-film resistors  52  are formed on a surface of the metal tube  51 , running circumferentially and spaced apart from one another. Alternatively, the resistors may follow a serpentine or zig zag path. Preferably, the resistors  52  are formed on the outer surface of the metal tube by a printing process. The sealing element  53  may be made of rubber, including a sealing tube  54  that covers the outer surface of the metal tube  51  and an extending ring  55  extending from the sealing tube  54 . Two axial ends  57  of the sealing tube  54  are sealed to the metal tube. Preferably, as shown in Fig. X, the axial ends of the sealing tube wrap around the axial ends of the metal tube to seal the sealing tube to the metal tube. The ends may be bonded together by adhesive, heat, etc or clamped or otherwise pressed together to form a seal by compression. The connecting ends  56  of the thick-film resistors  52  are exposed in an opening formed by the extending ring  55 . 
     The housing  60  is substantially barrel-shaped, including a substantially cylindrical lateral wall  61 , an end ring  62  extending radially inward from an axial end of the lateral wall  61 , an intake tube  63  extending along the axis of the lateral wall  61 , a guide portion  76  extending from the inner edge of the end ring  62  and connecting to the intake tube  63 , a discharge port  64  extending from the guide portion  76  substantially along a direction tangential to the lateral wall  61 , and a guide mechanism  65 . The lateral wall  61  has a through hole  67 . A fixing ring  68  extends outwardly from the edge of the through hole  67 . A second ring groove  69  is formed in the end ring  62 , radially spaced from the lateral wall  61 . A discharge aperture  70  is formed in the end ring  62 , between the second ring groove  69  and the lateral wall  61 . The discharge aperture  70  communicates with the discharge port  64 . 
     The lateral wall  61 , the end ring  62 , and the guide portion  76  jointly define a chamber  66  that communicates to the space outside the housing  60  through the intake tube  63 , the discharge port  64 , and the through hole  67 . The intake tube  63  is partially received at the center of the chamber  66 . The inner diameter of the intake tube  63  gradually becomes smaller from a region corresponding to the upper end of the housing towards the impeller, while at the end  73  of the intake tube  63  adjacent the impeller, the inner diameter of the intake tube  63  becomes larger. This increase in diameter is formed as a tapering or chamfering of the inner end of the intake tube so as to provide a restriction to the flow of the liquid being pumped from the outlet to the inlet of the impeller. Preferably, the inner end  73  of the intake tube generally follows the contour of the upper surface of the impeller or impeller blades. However, some cross flow is allowed to reduce friction and load on the motor when the outlet is blocked. The inlet  43  of the impeller  40  points toward the intake tube  63 , while a part of the inlet  43  is received in the distal end  73  of the intake tube  63  to reduce axial length of the heating pump  10 . The discharge port  64  is substantially arranged at a side of the end ring  62  that is opposite to the lateral wall  61 . 
     The guide mechanism  65  includes a ring  71  and a number of angled guide blades  72  extending radially outward from the ring  71  and axially along the ring. The ring  71  is pressed onto the inner end of the intake tube  63  such that it sits in a fixed manner. Preferably, the lateral wall  61 , end ring  62 , intake tube  63 , and discharge port  64  are formed as a single piece, monolithic construction, for example, by injection molding. Preferable, the guide mechanism  65  is formed as a separate piece, also by injection molding, and subsequently fitted to the intake tube. However, it should be understood that the guide blades  72  can also be integrally formed with the intake tube  63 . 
     The housing  60  is detachably assembled to the base  20 . The edge of the circular plate  21  tightly contacts the inner surface of the lateral wall  61 , so that the circular plate  43  can seal the open end of the chamber  66  remote from the end ring  62 . The two axial ends of the heating member  50  are respectively inserted into the first and second receiving grooves  24  and  69 . The axial ends  57  of the sealing tube  54  are thus pressed against the inner and outer surfaces of the axial ends of the metal ring  51 , whereby the heating member  50  is connected to the base  20  and the housing  60  in a liquid-tight manner. The extending ring  55  extends out of the fixing ring  68  and is sealingly connected thereto, for example, by a spring clamp  75  or glue. The connector  80  is electrically connected to the connecting ends  56  of the thick-film resistors  52  and is housed in the opening formed by the extending ring  55 . 
     In operation, the impeller  40  sucks liquid into the chamber  66  via the intake tube  63  and discharges it radially outwards as a result of centrifugal force. The moving speed of the liquid flow is accelerated due to the inner diameter gradually becoming smaller. The guide blades  72  of the guide mechanism  65  then transfer part of rotary motion of the liquid flow into vertical motion. Therefore, the liquid flows to the discharge port  64  in a spiral way through a first passage  12  formed between the inner surface of the heating member  50  and the outer surface of the intake tube  63 . During this process, the liquid contacts the inner surface of the metal tube  51  being heated by the thick-film resistors  52  and is heated to a desired temperature. At the same time, liquid ejected from the impeller  40  passes through the openings  25  of the base  20 , into a second passage  14  formed between the outer surface of the heating member  50  and the inner surface of the lateral wall  61 , passes through the discharge aperture  70  and into the discharge port  64  to be discharged. Since the outer surface of the heating member  50  is also heated by the thick-film resistors  52 , the liquid flowing through the second passage is also heated. As such, the heat efficiency is improved. 
     In the case that the discharge aperture  70  on the housing  60  is omitted, liquid can still flow into the second passage  14  where it is heated. A temperature drop then exists between liquid in the second passage  14  and liquid coming freshly from the impeller  40 , which causes the relatively hot water in the second passage  14  to flow back to the first passage  12 . Therefore, it should be understood that the heat efficiency can also be improved even the discharge aperture  70  is omitted. 
     Preferably, as shown in  FIGS. 3 and 5 , the housing  60  further includes a spiral rib  77  protruding from the inner surface of the lateral wall  61  for guiding the liquid in the second passage  14  to flow to the discharge port  64  in a spiral way. In this case, since liquid flows in both first and second passages  12 ,  14  in a spiral way, the time both liquid flows remain in contact with the heating member  50  is relatively longer, compared to the liquid flows passed the heating member  50  in a straight line. 
     Referring to  FIG. 6 , in other embodiments, the heating member  84  may include ring-shaped wire resistors  85  other than thick-film resistors  52 . The wire resistors  85  may be arranged within the metal tube  86 . In this case, the connectors of the wire resistors  85  can extend directly out of the end ring  62  for connecting to a power source. The sealing element  53 , the through hole  67 , and the fixing ring  68  can be omitted. This is especially easy if the housing is directly molded to the heating member  84 . 
     The annular wall  22  is configured for assembling the heating member  50  in a convenient way. However, referring to  FIG. 6 , it should be understood that the heating member  84  can also be just fixed to the end ring  62 , for example, by glue or welding, leaving a gap  74  between the other axial end of the heating member  84  and the circular plate  21 . Liquid can thus flow into the second passage  14  via the gap  74 . 
     Referring to  FIG. 7 , the impeller  90  may be a centrifugal impeller with two covers, a lower cover  41  and an upper cover  91 , defining the inlet  43  and the outlet  44 . The upper cover  91  is contoured and closely spaced from the inner end of the intake tube. 
     Referring to  FIGS. 7 and 8 , in other embodiments, the housing may be formed with a recess  92  in the upper end surface  93 . The intake tube  94  is received in the recess  92 . In this case, the inner surface of the heating member  50  and the radial outer surface  95  of the end surface  93  that surrounds the recess  92  cooperatively form a first passage  96  that performs the same function as the first passage  12 . Like the first passage  12 , the first passage  96  is also surrounded by the heating member  50 . 
     In the description and claims of the present application, each of the verbs “comprise”, “include”, “contain” and “have”, and variations thereof, are used in an inclusive sense, to specify the presence of the stated item but not to exclude the presence of additional items. 
     Although the invention is described with reference to one or more preferred embodiments, it should be appreciated by those skilled in the art that various modifications are possible. Therefore, the scope of the invention is to be determined by reference to the claims that follow.