Patent Publication Number: US-9903372-B2

Title: Pump, method for manufacturing pump, and refrigeration cycle device

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a U.S. national stage application of PCT/JP2012/076004 filed on Oct. 5, 2012, the contents of which are incorporated herein by reference. 
     FIELD 
     The present invention relates to a pump, a method for manufacturing a pump, and a refrigeration cycle device. 
     BACKGROUND 
     A DC brushless motor has been proposed for use in a magnet motor pump. The magnet motor pump includes a rotor having a rotor magnet integrally provided in the impeller, a stator having a stator coil provided on an outer periphery side of the rotor, and a Hall element for detecting the magnetic poles of the rotor magnet arranged inside the stator (see, for example, Patent Literature 1). 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Utility Model Laid-open Publication No. H05-23784 
     SUMMARY 
     Technical Problem 
     There is a problem however with the pump used with the magnet pump motor described in the above Patent Literature 1 in that, because the outer peripheral surface of the rotor magnet is covered with a thermoplastic resin, the distance between the stator and the rotor magnet is increased and thus the performance of the pump is possibly reduced. 
     The present invention has been achieved in view of the above problem, and an objective of the present invention is to provide a pump that can prevent magnets from cracking due to the thermal shock associated with a cold/hot water cycle without the outer peripheral surface of the magnet being covered with resin, to provide a method for manufacturing the pump, and to provide a refrigeration cycle device including the pump. 
     Solution to Problem 
     The present invention is made to solve the problem and achieve the objective mentioned above and is relates to a pump that includes: an annular molded stator having a substrate upon which is mounted a magnetic-pole position detection element; and a rotor having an annular rotor unit rotatably housed in a cup-shaped partition component, with one end thereof in an axial direction opposing the magnetic-pole position detection element and with the other end thereof in the axial direction being provided with an impeller attachment unit to which an impeller is attached. The rotor unit includes an annular magnet, a sleeve bearing provided inside of the magnet, and a resin portion formed from a thermoplastic resin from which an integral molding is made for the magnet and the sleeve bearing and that constitutes the impeller attachment unit, the magnet includes a plurality of through holes, each extending in the axial direction between an end face on a side of the magnetic-pole position detection element and an end face on a side of the impeller attachment unit, and each of the through holes is embedded in the thermoplastic resin that constitutes a part of the resin portion. 
     Advantageous Effects of Invention 
     According to the present invention, a plurality of through holes, each extending in an axial direction, is provided in a magnet that constitutes a rotor unit, and each of the through holes is embedded in a thermoplastic resin when they are integrally molded. Therefore, the magnet is firmly held by the thermoplastic resin and is prevented from cracking due to the thermal shock associated with a cold/hot water cycle without the outer peripheral surface of the magnet being covered with the resin. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a configuration diagram of a heat-pump type water heater according to a first embodiment. 
         FIG. 2  is an exploded perspective view of a pump  10  according to the first embodiment. 
         FIG. 3  is a perspective view of a molded stator  50 . 
         FIG. 4  is a cross-sectional view of the molded stator  50 . 
         FIG. 5  is an exploded perspective view of a stator assembly  49 . 
         FIG. 6  is an exploded perspective view of a pump unit  40 . 
         FIG. 7  is a cross-sectional view of the pump  10 . 
         FIG. 8  is a perspective view of a casing  41  viewed from a side of a shaft support portion  46 . 
         FIG. 9  is a cross-sectional view of a rotor unit  60   a  (specifically, a cross-sectional view on arrow A-A in  FIG. 11 ). 
         FIG. 10  is a view of the rotor unit  60   a  viewed from a side of an impeller attachment unit. 
         FIG. 11  is a view of the rotor unit  60   a  viewed from an opposite side to the side of the impeller attachment unit. 
         FIG. 12  is an enlarged cross-sectional view of a sleeve bearing  66 . 
         FIG. 13  is a cross-sectional view of a resin magnet  68  (specifically, a cross-sectional view on arrow B-B in  FIG. 14 ). 
         FIG. 14  is a view of the resin magnet  68  viewed from the side of a protrusion  68   a  (the side of the impeller attachment unit). 
         FIG. 15  is a view of the resin magnet  68  viewed from an opposite side to the side of the protrusion  68   a.    
         FIG. 16  is a perspective view of the resin magnet  68  viewed from the side of the protrusion  68   a.    
         FIG. 17  is a perspective view of the resin magnet  68  viewed from the opposite side to the side of the protrusion  68   a.    
         FIG. 18  is a perspective view of the rotor unit  60   a  viewed from the side of the impeller attachment unit. 
         FIG. 19  is a perspective view of the rotor unit  60   a  viewed from an opposite side to the side of the impeller attachment unit. 
         FIG. 20  illustrates a manufacturing process of the pump  10 . 
         FIG. 21  is a conceptual diagram illustrating a circuit in a refrigeration cycle device that uses a refrigerant-water heat exchanger. 
         FIG. 22  is a sectional view of the rotor unit  60   a  according to a second embodiment. 
         FIG. 23  is a sectional view of the resin magnet  68  according to the second embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Exemplary embodiments of a pump, a method for manufacturing a pump, and a refrigeration cycle device according to the present invention will be explained below in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments. 
     First Embodiment 
     In the following descriptions, an outline of a heat-pump type water heater as an example of application of the pump according to the present embodiment is described first, and details of the pump are given next. 
       FIG. 1  is a configuration diagram of a heat-pump type water heater according to the present embodiment. As illustrated in  FIG. 1 , a heat-pump type water heater  300  includes a heat pump unit  100 , a tank unit  200 , and an operating unit  11  that is used when a user performs a drive operation and the like. 
     In  FIG. 1 , the heat pump unit  100  includes a compressor  1  (for example, a rotary compressor or a scroll compressor) that compresses a refrigerant; a refrigerant-water heat exchanger  2  in which heat is exchanged between the refrigerant and water; a decompression device  3  that decompresses and expands the high-pressure refrigerant; an evaporator  4  that evaporates a low-pressure two-phase refrigerant; a refrigerant pipe  15  that connects the compressor  1 , the refrigerant-water heat exchanger  2 , the decompression device  3 , and the evaporator  4  in a circular circuit; a pressure detection device  5  that detects discharge pressure of the compressor  1 ; a fan  7  that blows air into the evaporator  4 ; and a fan motor  6  that drives the fan  7 . The compressor  1 , the refrigerant-water heat exchanger  2 , the decompression device  3 , the evaporator  4 , and the refrigerant pipe  15  that connects these in a circular circuit constitute a refrigerant circuit. 
     The heat pump unit  100  includes a boiling-point temperature detection unit  8  of the refrigerant-water heat exchanger  2 ; a feed-water temperature detection unit  9  of the refrigerant-water heat exchanger  2 ; and an ambient-air temperature detection unit  17 , as a temperature detection unit. 
     The heat pump unit  100  also includes a heat-pump-unit control unit  13 . The heat-pump-unit control unit  13  receives signals from the pressure detection device  5 , the boiling-up temperature detection unit  8 , the feed-water temperature detection unit  9 , and the ambient-air temperature detection unit  17  and executes control of the number of revolutions of the compressor  1 , control of the opening degree of the decompression device  3 , and control of the number of revolutions of the fan motor  6 . 
     The tank unit  200  includes a hot water tank  14  that stores hot water heated by exchanging heat with the high-temperature and high-pressure refrigerant in the refrigerant-water heat exchanger  2 ; a bathwater-reheating heat exchanger  31  that reheats bathwater; a bathwater circulating device  32  connected to the bathwater-reheating heat exchanger  31 ; a pump  10  being a hot-water circulating device arranged between the refrigerant-water heat exchanger  2  and the hot water tank  14 ; a hot-water circulating pipe  16  that connects the refrigerant-water heat exchanger  2  and the hot water tank  14 ; a mixing valve  33  connected to the refrigerant-water heat exchanger  2 , the hot water tank  14 , and the bathwater-reheating heat exchanger  31 ; and a bathwater reheating pipe  37  that connects the hot water tank  14  and the mixing valve  33 . The refrigerant-water heat exchanger  2 , the hot water tank  14 , the pump  10 , and the hot-water circulating pipe  16  constitute a water circuit. 
     The tank unit  200  also includes an in-tank water-temperature detection unit  34 ; a reheated water-temperature detection unit  35  that detects the water temperature after it has passed through the bathwater-reheating heat exchanger  31 ; and a mixed water-temperature detection unit  36  that detects the water temperature after it has passed through the mixing valve  33 , as a temperature detection unit. 
     The tank unit  200  further includes a tank-unit control unit  12 . The tank-unit control unit  12  receives signals from the in-tank water-temperature detection unit  34 , the reheated water-temperature detection unit  35 , and the mixed water-temperature detection unit  36 , in order to execute control of the number of revolutions of the pump  10  and opening/closing control of the mixing valve  33 . The tank unit  200  further performs sending and receiving of signals to and from the heat-pump-unit control unit  13  and to and from the operating unit  11 . 
     The operating unit  11  is a remote controller or an operation panel including a switch for a user to set the temperature setting of the hot water or to instruct hot water to be supplied. 
     In  FIG. 1 , a normal boiling operation in the heat-pump type water heater  300  configured as described above is explained. When a boiling operation instruction from the operating unit  11  or the tank unit  200  is transmitted to the heat-pump-unit control unit  13 , the heat pump unit  100  performs a boiling operation. 
     The heat-pump-unit control unit  13  executes control of the number of revolutions of the compressor  1 , control of the opening degree of the decompression device  3 , and control of the number of revolutions of the fan motor  6  on the basis of the detection values of the pressure detection device  5 , the boiling-up temperature detection unit  8 , and the feed-water temperature detection unit  9 . 
     Further, the detection value detected by the boiling-up temperature detection unit  8  is transferred between the heat-pump-unit control unit  13  and the tank-unit control unit  12 ; and the tank-unit control unit  12  controls the number of revolutions of the pump  10  so that the temperature detected by the boiling-up temperature detection unit  8  becomes a target boiling-up temperature. 
     In the heat-pump type water heater  300  controlled as described above, the high-temperature and high-pressure refrigerant discharged from the compressor  1  reduces its temperature, while dissipating heat to a water supply circuit. The high-temperature and high-pressure refrigerant, which has dissipated heat and passed through the refrigerant-water heat exchanger  2 , is decompressed by the decompression device  3 . The refrigerant having passed through the decompression device  3  flows into the evaporator  4 , and absorbs heat from ambient-air. The low-pressure refrigerant having been discharged from the evaporator  4  is drawn into the compressor  1  to repeat circulation, thereby forming a refrigeration cycle. 
     Meanwhile, water in a lower part in the hot water tank  14  is guided to the refrigerant-water heat exchanger  2  driven by the pump  10  which is the hot-water circulating device. Water is heated by heat dissipation from the refrigerant-water heat exchanger  2 ; and the heated hot water passes through the hot-water circulating pipe  16  and is returned to an upper part of the hot water tank  14  and stored. 
     As explained above, in the heat-pump type water heater  300 , the pump  10  is used as the hot-water circulating device that circulates hot water through the hot-water circulating pipe  16  between the hot water tank  14  and the refrigerant-water heat exchanger  2 . 
     The pump  10  according to the present embodiment is explained next.  FIG. 2  is an exploded perspective view of the pump  10  according to the present embodiment. 
     As illustrated in  FIG. 2 , the pump  10  includes a pump unit  40  that absorbs and discharges water by the revolution of the rotor (described later); a molded stator  50  that drives the rotor; and tapping screws  160  that fasten the pump unit  40  to the molded stator  50 . In an example illustrated in  FIG. 2 , the number of tapping screws  160  is, for example, five. However, the number of tapping screws is not limited thereto. 
     The pump  10  is assembled by fastening five tapping screws  160  to pilot holes  84  of a pilot hole component  81  (for details, refer to  FIG. 5  illustrated later) embedded in the molded stator  50  via screw holes  44   a  formed in a boss  44  of the pump unit  40 . 
     In  FIG. 2 , a casing  41 , an intake  42 , a discharge outlet  43 , a cup-shaped partition component  90 , a lead wire  52 , a mold resin  53 , a stator iron core  54 , and a pump-unit installation surface  63  are illustrated but they do not appear in the configurations explained above. These elements are explained later. 
     The configuration of the molded stator  50  is explained first with reference to  FIGS. 3 to 5 .  FIG. 3  is a perspective view of the molded stator  50 ,  FIG. 4  is a cross-sectional view of the molded stator  50 , and  FIG. 5  is an exploded perspective view of a stator assembly  49 . 
     The molded stator  50  is acquired by molding the stator assembly  49  by using the mold resin  53  ( FIGS. 3 and 4 ). 
     On one end face of the molded stator  50  in an axial direction, specifically, on an end face on the side of the pump unit  40  (refer also to  FIG. 2 ), a flat pump-unit installation surface  63  is provided along an outer peripheral edge thereof. 
     A leg part  85  (refer to  FIGS. 4 and 5 ) of the pilot hole component  81  is axially embedded at five places in the pump-unit installation surface  63 . The leg part  85  is, for example, a substantially columnar resin molded component. At the time of mold forming by using the mold resin  53 , one end face of the leg part  85  (the end face on the side of the pump unit  40 ) becomes a die pressing part  82  of a molding die (refer to  FIG. 4 ). Therefore, the pilot hole component  81  is exposed in a form of being embedded inward from the pump-unit installation surface  63  by a predetermined distance. The exposed parts are the die pressing part  82  and the pilot hole  84  for the tapping screw  160 . 
     The lead wire  52  pulled out from the stator assembly  49  is pulled out to the outside from a vicinity of the axial end face of the molded stator  50  opposite to the side of the pump unit  40 . 
     Axial positioning of the molded stator  50  by the mold resin  53  (for example, thermosetting resin) at the time of mold forming is performed by axial end faces of a plurality of protrusions  95   a , which are formed in a substrate pressing component  95  (refer to  FIG. 5 ), functioning as a pressing part of an upper die. Therefore, the axial end faces (die pressing surfaces) of the protrusions  95   a  are exposed (not illustrated) from the axial end face of the molded stator  50  on a side of a substrate  58 . 
     An axial end face of an insulation part  56  on an opposite side to a wire connection (on the side of the pump unit  40 ) becomes a die pressing part of a lower die. Accordingly, from the axial end face of the molded stator  50  on the opposite side to the substrate  58 , the end face of the insulation part  56  on the opposite side to the wire connection is exposed (not illustrated). 
     Radial positioning of the molded stator  50  at the time of mold forming is made by fitting an inner periphery of the stator iron core to the die. Therefore, tip ends of teeth (the inner periphery) of the stator iron core  54  are exposed to the inner periphery of the molded stator  50  illustrated in  FIG. 3 . 
     The internal configuration of the molded stator  50 , that is, the configuration or the like of the stator assembly  49  is described next. 
     As illustrated in  FIG. 5 , the stator assembly  49  includes a stator  47  and a pilot hole component  81 . As illustrated in  FIGS. 4 and 5 , the stator  47  includes the lead wire  52 , the stator iron core  54  provided with grooves  54   a , the insulation part  56 , a coil  57 , an IC  58   a , a Hall element  58   b , the substrate  58 , a terminal  59 , a lead-wire leading component  61 , and a substrate pressing component  95 . The pilot hole component  81  includes leg parts  85 , protrusions  83  and  85   a  provided in the leg parts  85 , and a connection part  87 . 
     The stator assembly  49  is manufactured in the procedure described below. 
     (1) An electromagnetic steel plate having a thickness of, for example, 0.1 millimeter to 0.7 millimeter is punched in a belt-like form, and the annular stator iron core  54  laminated by swaging, welding, or bonding is made from the electromagnetic steel plate. The stator iron core  54  has a plurality of teeth. Tip ends of the teeth of the stator iron core  54  are exposed to the inner periphery of the molded stator  50  illustrated in  FIG. 3 . The stator iron core  54  illustrated here has, for example, 12 teeth connected with thin connection parts. Therefore, in  FIG. 3 , the tip ends of the teeth of the stator iron core  54  are exposed at 12 positions. However, only five teeth of the 12 teeth are viewed in  FIG. 3 .
 
(2) The insulation part  56  is applied to the teeth of the stator iron core  54 . The insulation part  56  is formed integrally with or separately to the stator iron core  54  by using, for example, a thermoplastic resin such as PBT (polybutylene terephthalate).
 
(3) A concentratedly wound coil  57  (refer to  FIG. 4 ) is wound around the teeth applied with the insulation part  56 . By connecting 12 concentratedly wound coils  57 , three-phase single Y-connection windings are formed.
 
(4) Because of the three-phase single Y-connection, terminals  59  (refer to  FIG. 4 , supply terminals to which power is supplied, and a neutral terminal) to which the coils  57  (refer to  FIG. 4 ) of respective phases (a U phase, a V phase, and a W phase) are connected are assembled on the connection side of the insulation part  56 . There are three supply terminals and one neutral terminal.
 
(5) The substrate  58  is attached to the insulation part  56  on the connection side (on the side where the terminals  59  are assembled). The substrate  58  is held between the substrate pressing component  95  and the insulation part  56 . An electronic component is mounted on the substrate  58 , for example, the IC  58   a  (drive element) that drives a motor (for example, a brushless DC motor), the Hall element  58   b  that detects the position of the rotor  60  (refer to  FIG. 4 , a magnetic-pole position detection element), and the like are provided thereon. Because the IC  58   a  is mounted on the side of the substrate pressing component  95  of the substrate  58 , it is illustrated in  FIG. 5 . However, the Hall element  58   b  is hidden and not seen in  FIG. 5 , because it is mounted on the opposite side to the IC  58   a . Further, the substrate  58  is attached with the lead-wire leading component  61  that leads out the lead wire  52  in a notched portion near the outer periphery thereof.
 
(6) The substrate  58  attached with the lead-wire leading component  61  is fixed to the insulation part  56  by the substrate pressing component  95 ; and the pilot hole component  81  is assembled on the stator  47  to which the terminals  59  and the substrate  58  are soldered, thereby completing the stator assembly  49  (refer to  FIG. 5 ).
 
     The configuration of the pilot hole component  81  is explained next with reference to  FIG. 5 . The pilot hole component  81  is formed by molding a thermoplastic resin such as PBT (polybutylene terephthalate). 
     As illustrated in  FIG. 5 , the pilot hole component  81  is configured by circularly connecting a plurality (for example, five) of leg parts  85  in a substantially columnar shape with the thin connection part  87 . The leg part  85  is provided with the pilot hole  84  to be screwed into with the tapping screw  160  (refer to  FIG. 2 ). The leg part  85  has a tapered shape, in which the leg part  85  becomes thicker from the exposed end face (the die pressing part  82  and the end face of the protrusion  83 ) toward the axial center. By having such a tapered shape, the pilot hole component  81  is effectively prevented from falling off after performing mold forming with the stator  47 . 
     The pilot hole component  81  includes the plurality of protrusions  85   a  on the outer periphery of the leg part  85  for preventing rotation. In the example illustrated in  FIG. 5 , four protrusions  85   a  are provided on the outer periphery of the leg part  85 . The protrusion  85   a  is formed to extend in a height direction (an axial direction) of the leg part  85  with a predetermined circumferential width. Further, the protrusion  85   a  protrudes from an outer peripheral surface of the leg part  85  by a required predetermined dimension in order to prevent the pilot hole component  81  from being rotated. The pilot hole component  81  can be set to the molding die in the first attempt by connecting the substantially columnar leg parts  85  with the thin connection part  87 , thereby enabling the machining cost to be reduced. 
     By providing a plurality of claws (not illustrated) for assembling the pilot hole component  81  on the stator  47  in the connection part  87  of the pilot hole component  81  and latching the claws of the pilot hole component  81  into the grooves  54   a  formed on the outer periphery of the stator iron core  54  of the stator  47 , the stator  47  and the pilot hole component  81  can be set to the molding die in the first attempt, thereby enabling the machining cost to be reduced. 
     When the stator assembly  49  is mold-formed by the mold resin  53  after latching the pilot hole component  81  to the stator  47 , the axial positioning of the pilot hole component  81  is performed by holding the die pressing part  82  and the protrusions  83  of the pilot hole component  81  by the mold forming die. 
     An outer diameter of the die pressing part  82  can be set smaller than an outer diameter of an opening-side end face of the pilot hole component  81  (refer to  FIG. 4 ). Thus, the end face of the pilot hole component  81  of a portion excluding the die pressing part  82  is covered with the mold resin  53 . Therefore, because the opposite end face of the pilot hole component  81  is covered with the mold resin  53 , exposure of the pilot hole component  81  is suppressed, thereby enabling the quality of the pump  10  to be improved. 
     The molded stator  50  is obtained by integrally molding the pilot hole component  81  assembled on the stator  47  by the mold resin  53 . In this case, the pilot holes  84  are molded so as to be exposed. By and assembling and fastening the pump unit  40  and the molded stator  50  to the pilot hole  84  with the tapping screws  160  via the screw holes  44   a  formed in the pump unit  40 , the pump unit  40  and the molded stator  50  can be firmly assembled together (refer to  FIG. 2 ). 
     The configuration of the pump unit  40  is to be explained next with reference to  FIGS. 6 to 8 .  FIG. 6  is an exploded perspective view of the pump unit  40 ,  FIG. 7  is a cross-sectional view of the pump  10 , and  FIG. 8  is a perspective view of the casing  41  viewed from a side of a shaft support portion  46 . The pump unit  40  includes the following elements: 
     (1) Casing  41  that has the intake  42  and the discharge outlet  43  of fluid and houses an impeller  60   b  of the rotor  60  therein: The casing  41  is molded by using a thermoplastic resin, for example, PPS (polyphenylene sulfide). A boss  44  with a screw hole  44   a , which is used at the time of assembling the pump unit  40  and the molded stator  50 , is provided at five positions.
 
(2) Thrust bearing  71 : The material of the thrust bearing  71  is a ceramic, for example, alumina. The rotor  60  is pressed against the casing  41  via the thrust bearing  71 , due to a pressure difference acting on the both sides of the impeller  60   b  of the rotor  60  during the operation of the pump  10 . Therefore, a thrust bearing made of a ceramic is used as the thrust bearing  71  to ensure wear resistance and sliding properties.
 
(3) Rotor  60 : The rotor  60  includes a rotor unit  60   a  and the impeller  60   b . In the rotor unit  60   a , a ring-shaped (cylindrical or annular) resin magnet  68  (an example of a magnet) molded by using a pellet formed by kneading a magnetic powder, for example, ferrite powder and resin and a cylindrical sleeve bearing  66  (for example, made of carbon) provided inside of the resin magnet  68  are integrated at a resin portion  67  made of such as, for example, PPE (polyphenylene ether) (refer to  FIG. 9  explained later). The impeller  60   b  is a resin molded product of, for example, PPE (polyphenylene ether). The rotor unit  60   a  and the impeller  60   b  are bonded by, for example, ultrasonic welding.
 
(4) Shaft  70 : The material of the shaft  70  (a rotary shaft) is a ceramic, for example, alumina, or SUS. Because the shaft  70  slides with the sleeve bearing  66  provided in the rotor  60 , a material such as a ceramic or SUS is selected so as to ensure the wear resistance and sliding properties. One end of the shaft  70  is inserted into a shaft support portion  94  of the cup-shaped partition component  90 ; and the other end of the shaft  70  is inserted into the shaft support portion  46  of the casing  41 . Therefore, the one end of the shaft  70  to be inserted into the shaft support portion  94  is inserted therein so as not to rotate with respect to the shaft support portion  94 . Therefore, the one end of the shaft  70  is substantially D shaped, which is obtained by cutting a part of a circular form by a predetermined length (in an axial direction). A hole in the shaft support portion  94  has a shape matched with the shape of the one end of the shaft  70 . Further, the other end of the shaft  70  to be inserted into the shaft support portion  46  is also substantially D shaped, which is obtained by cutting a part of a circular form by a predetermined length (in an axial direction), and thus the shaft  70  has a symmetrical shape in a lengthwise direction. However, the other end of the shaft  70  is inserted rotatably into the shaft support portion  46 . The reason why the shaft is symmetrical in the lengthwise direction is because, at the time of inserting the shaft  70  into the shaft support portion  94 , it is possible to assemble it without taking into consideration whether the direction is up or down (refer to  FIG. 6 ).
 
(5) O-ring  80 : The material of the O-ring  80  is, for example, EPDM (ethylene-propylene-diene rubber). The O-ring  80  seals the casing  41  from the cup-shaped partition component  90  of the pump unit  40 . In a pump mounted on a hot water dispenser, heat resistance and long life are required for sealing the piping. Therefore, the material such as EPDM is used to ensure the resistance properties.
 
(6) Cup-shaped partition component  90 : The cup-shaped partition component  90  is molded by using a thermoplastic resin, for example, PPE (polyphenylene ether). The cup-shaped partition component  90  includes a cup-shaped partition wall portion  90   a  that is a joint with the molded stator  50 , and a flange portion  90   b . The cup-shaped partition wall portion  90   a  is formed of a circular bottom and a cylindrical partition wall. The shaft support portion  94 , into which the one end of the shaft  70  is inserted, is provided in a standing condition substantially at the center on an internal surface of the bottom of the cup-shaped partition wall portion  90   a . On an external surface of the bottom of the cup-shaped partition wall portion  90   a , a plurality of ribs  92  are radially formed in a radial direction. A plurality of reinforcing ribs (not illustrated) are radially formed on the flange portion  90   b  in the radial direction. The flange portion  90   b  also includes an annular rib (not illustrated) housed in the pump-unit installation surface  63  of the pump unit  40 . The flange portion  90   b  is formed with a hole  90   d , through which the tapping screw  160  passes, at five positions. A circular O-ring housing groove  90   c  for housing the O-ring  80  is formed on a surface of the flange portion  90   b  on the side of the casing  41 .
 
     The pump  10  is constructed by fixing the casing  41  to the cup-shaped partition component  90  after installing the O-ring  80  in the cup-shaped partition component  90  and installing the shaft  70 , the rotor  60 , and the thrust bearing  71  in the cup-shaped partition component  90  to construct the pump unit  40 ; and further fixing the pump unit  40  to the molded stator  50  by the assembly tapping screws  160  and the like. 
     By fitting the ribs  92  provided on the bottom of the cup-shaped partition component  90  to the groove (not illustrated) in the molded stator  50 , circumferential positioning of the pump unit  40  and the molded stator  50  is performed. 
     The rotor  60  is housed inside of the cup-shaped partition wall portion  90   a . The rotor  60  is fitted to the shaft  70  inserted into the shaft support portion  94  of the cup-shaped partition component  90 . Therefore, to ensure concentricity between the molded stator  50  and the rotor  60 , it is better to keep the gap between an inner circumference of the molded stator  50  and an outer circumference of the cup-shaped partition wall portion  90   a  as small as possible. For example, the gap is set to be about 0.02 millimeter to 0.06 millimeter. 
     However, if the gap between the inner circumference of the molded stator  50  and the outer circumference of the cup-shaped partition wall portion  90   a  is too small, the escape route for air becomes narrow when the cup-shaped partition wall portion  90   a  is inserted into the inner circumference of the molded stator  50 , thereby making it difficult to insert the cup-shaped partition component  90 . 
       FIG. 9  is a cross-sectional view of the rotor unit  60   a  (specifically, a cross-sectional view along arrow A-A in  FIG. 11 );  FIG. 10  is a view of the rotor unit  60   a  viewed from a side of an impeller attachment unit;  FIG. 11  is a view of the rotor unit  60   a  viewed from an opposite side to the side of the impeller attachment unit; and  FIG. 12  is an enlarged cross-sectional view of the sleeve bearing  66 . 
     The rotor unit  60   a  is explained with reference to  FIGS. 9 to 12 . As illustrated in  FIGS. 9 to 12 , the rotor unit  60   a  includes at least the following elements: 
     (1) Resin magnet  68 ; 
     (2) Sleeve bearing  66 ; and 
     (3) Resin portion  67 . The resin portion  67  is constituted by a thermoplastic resin, for example, PPE (polyphenylene ether). The impeller attachment unit  67   a , to which the impeller  60   b  is attached, is formed in the resin portion  67 . The resin magnet  68  and the sleeve bearing  66  are integrally molded by using the resin portion  67 . 
     The resin magnet  68  is substantially ring shaped (cylindrical or annular shape), and is molded by using the pellet formed by kneading it with a magnetic powder, for example, ferrite powder and resin. 
     The sleeve bearing  66  (for example, made of carbon) is provided inside of the resin magnet  68 . The sleeve bearing  66  has a cylindrical shape. The sleeve bearing  66  is fitted to the shaft  70  which is assembled on the cup-shaped partition component  90  of the pump  10  to rotate. Therefore, the sleeve bearing  66  is fabricated by a material suitable for the bearing, for example, a thermoplastic resin such as PPS (polyphenylene sulfide) added with sintered carbon or carbon fiber, or a ceramic. The sleeve bearing  66  is provided with a drawing-out taper (not illustrated), which has an outer diameter decreasing with distance from a substantially axial center toward the opposite ends, and is provided with, for example, a plurality of semispherical protrusions  66   a  (refer to  FIG. 12 ) on an outer periphery, which prevent the rotation substantially at an axial center. 
     A depression  67   b  is formed in a portion contacting to an end face of the resin magnet  68  on the side of the impeller attachment unit of the resin portion  67 , corresponding to a magnet pressing part (not illustrated) provided on the upper die of the resin molding die. The depression  67   b  is formed substantially at the center in a radial direction in the example illustrated in  FIG. 9 . The depression  67   b  is formed at a position substantially facing the protrusion  68   a  of the resin magnet  68  in the axial direction. 
     As illustrated in  FIG. 10 , a plurality of impeller positioning holes  67   c  for attaching the impeller  60   b  are made in the impeller attachment unit  67   a . For example, three impeller positioning holes  67   c  are formed substantially at a regular interval in the circumferential direction. The impeller positioning holes  67   c  penetrate the impeller attachment unit  67   a . The impeller positioning holes  67   c  are respectively formed on a radial extension line in the middle of two protrusions  68   a  (refer to  FIG. 10 ) among the three protrusions of the resin magnet  68 . 
     Furthermore, as illustrated in  FIG. 10 , for example, three gates  67   e , which are to be used when the rotor unit  60   a  is molded by using the thermoplastic resin (the resin portion  67 ), are respectively formed substantially at a regular interval in the circumferential direction. The respective gates  67   e  are formed on the radial extension line of the protrusions of the resin magnet  68 , and inside relative to the impeller positioning holes  67   c.    
     Notches  67   d  to be fitted to a positioning protrusion (not illustrated) provided in the lower die of the resin molding die are formed in a portion of the resin portion  67  formed by contacting to an inner periphery of the resin magnet  68  opposite to the side of the impeller attachment unit  67   a  (refer to  FIGS. 9 and 11 ). The notch  67   d  are formed at four positions substantially with an interval of 90 degrees in the example illustrated in  FIG. 11 . A plurality (eight in the example illustrated in  FIG. 11 ) of protrusions  68   e , being a part of the resin magnet  68 , are exposed from the resin portion  67  (refer to  FIG. 11 ). 
     A plurality of through holes  69 , each extending in the axial direction and being provided in the resin magnet  68 , and the inside of each of the through holes  69  is filled with the thermoplastic resin. That is, the thermoplastic resin in the through holes  69  constitutes a part of the resin portion  67 . 
       FIG. 13  is a cross-sectional view of a resin magnet  68  (specifically, a cross-sectional view in the direction of arrow B-B in  FIG. 14 );  FIG. 14  is a view of the resin magnet  68  viewed from the side of a protrusion  68   a  (the side of the impeller attachment unit);  FIG. 15  is a view of the resin magnet  68  viewed from an opposite side to the side of the protrusion  68   a ;  FIG. 16  is a perspective view of the resin magnet  68  viewed from the side of the protrusion  68   a ; and  FIG. 17  is a perspective view of the resin magnet  68  viewed from the opposite side to the side of the protrusion  68   a .  FIG. 18  is a perspective view of the rotor unit  60   a  viewed from the side of the impeller attachment unit; and  FIG. 19  is a perspective view of the rotor unit  60   a  viewed from an opposite side to the side of the impeller attachment unit. 
     The configuration of the resin magnet  68  is explained referring to  FIGS. 13 to 19 . The resin magnet  68  illustrated here has, for example, eight magnetic poles. The resin magnet  68  includes a plurality of tapered notches  68   b , each arranged substantially at a regular interval in the circumferential direction on the inner periphery side of an end face opposite to the side of the impeller attachment unit  67   a . That is, the notches  68   b  are formed on the inner periphery of the end face and are axially extended from the end face by a predetermined length. In the example illustrated in  FIG. 15 , there are eight notches  68   b . The notch  68   b  has a tapered shape with a diameter increasing on the end face side compared to the axial center side. The notches  67   d  of the resin portion  67  (refer to  FIG. 11 ) are formed at the same positions as the four notches  68   b  arranged substantially at an interval of 90 degrees. 
     The resin magnet  68  includes a plurality of protrusions  68   a , each being, for example, substantially horn shaped and extending axially by a predetermined length substantially at a regular interval in the circumferential direction on an inner periphery side at a predetermined depth from the end face opposite to the side where the notches  68   b  are formed. In the example illustrated in  FIG. 14 , there are three protrusions  68   a.    
     As illustrated in  FIG. 14 , each protrusion  68   a  has a convex portion  68   a - 1  that is substantially horn shapes when viewed from the side and protrudes toward the end face. When the rotor unit  60   a  is molded integrally, the convex portion  68   a - 1  provided at the end of the protrusion  68   a  is held by the thermoplastic resin (the resin portion  67 ) that forms the rotor unit  60   a . Accordingly, even if a slight gap is formed between the resin portion  67  and the resin magnet  68  due to resin shrinkage, the rotation torque of the resin magnet  68  can be reliably transmitted, thereby enabling the quality of the rotor unit  60   a  to be improved. The shape of the protrusion  68   a  is not limited to being substantially horn shaped, and can be any shape such as a triangle, trapezoid, semicircle, circular arc, or polygon. 
     The resin magnet  68  includes a plurality of gates  68   c  on the end face on the side of the magnetic-pole position detection element (the Hall element  58   b  (see  FIG. 4 )). Each of the gates  68   c  is molded into the rotor  60  (see  FIG. 15 ) and each of the gates  68   c  is supplied with a plastic magnet (a material of the resin magnet  68 ). Note that the end face on the side of the magnetic-pole position detection element is an end face opposing the magnetic-pole position detection element from among the end faces of the resin magnet  68 . The position of the gate  68   c  is, for example, at a magnetic pole center (see  FIG. 15 ). By having the gate  68   c  at the magnetic pole center, orientation accuracy of the resin magnet  68  can be improved. 
     As illustrated in  FIG. 13 , a hollow portion of the resin magnet  68  has a straight shape from the end face where the protrusions  68   a  are formed to the substantially center position in the axial direction (the structural center position in the axis direction) and has a drawing-out taper shape from the end face opposite to the end face where the protrusions  68   a  are formed to the substantially center position in the axial direction. Accordingly, the molded article can be easily taken out from the die, thereby enabling the productivity of the resin magnet  68  to be improved and the production cost to be reduced. That is, because the hollow portion of the resin magnet  68  has a drawn-out taper shape, it can be prevented that a part of or whole of the molded article is stuck to the die and is hard to taken out (adhesion to the die), thereby enabling the productivity of the resin magnet  68  to be improved. The die for molding the resin magnet  68  is divided into a fixed die and a movable die on the end face on the drawn-out taper side of the protrusion  68   a . Because a part of the hollow portion formed by the movable die has a straight shape, sticking to the fixed die can be prevented further, and the productivity of the resin magnet  68  can be improved. The resin magnet  68  is pushed out from the movable die by an ejector pin. 
     As illustrated in  FIGS. 13 to 15 , a plurality (eight in the example illustrated in  FIG. 15 ) of through holes  69 , each extending in the axial direction from the end face on the side of the magnetic-pole position detection element (the Hall element  58   b ) to the end face on the side of the impeller attachment unit, are formed in the resin magnet  68 , each substantially on the same circumference. The through hole  69  is, for example, a circular shape in cross section. The cross-sectional shape of the through hole  69  is not limited to a circular shape, and can be any shape such as a triangle, trapezoid, semicircle, H-shape, crescent, or polygonal shape (not illustrated). 
     As illustrated in  FIGS. 14 and 15 , the through holes  69  are respectively formed between the magnetic poles formed in the rotor  60 . By forming the through holes  69  between the magnetic poles, the decrease in the magnetic force is reduced as much as possible, and thus a performance decrease of the pump  10  can be reduced. 
     As illustrated in  FIG. 15 , a plurality (eight in the example illustrated in  FIG. 15 ) of protrusions  68   e , having a substantially elongated hole shape in cross section, are radially formed on the end face opposite to the magnetic-pole position detection element (the Hall element  58   b ) of the resin magnet  68 . 
     As illustrated in  FIG. 15 , the protrusions  68   e  formed on the side of the magnetic-pole position detection element (the Hall element  58   b ) are formed, for example, substantially at the center of the magnetic poles formed in the rotor  60 . That is, the protrusions  68   e  are arranged corresponding to the positions of the gates  68   c , to each of which the material of the resin magnet  68  is supplied. Further, the protrusions  68   e , a plurality thereof (for example, eight in the example illustrated in  FIG. 15 ), are formed on the same circumference. By providing the protrusions  68   e  at the magnetic pole center, the magnetic force is improved and the performance of the pump  10  can be improved. 
     When the rotor unit  60   a  is integrally molded from the thermoplastic resin (the resin portion  67 ), the through holes  69  and the protrusions  68   e  are embedded in the thermoplastic resin (the resin portion  67 ), and the resin magnet  68  is held in the resin portion  67 . 
     The resin magnet  68  is provided with a rotor-position detecting magnetic-pole portion  68   f , which protrudes axially with a predetermined height in an annular shape having a predetermined width in a radial direction (refer to  FIGS. 13, 15, 17 and 19 ), on an outer periphery of the end face on the magnetic-pole position detection element (the Hall element  58   b ). In this manner, by causing a part of the resin magnet  68  to protrude toward the magnetic-pole position detection element (the Hall element  58   b ) as the rotor-position detecting magnetic-pole portion  68   f  so as to reduce the axial distance between the rotor-position detecting magnetic-pole portion  68   f  of the resin magnet  68  and the Hall element  58   b  mounted on the substrate  58 , the detection accuracy of the magnetic pole position can be improved. 
     As the magnetic-pole position detection element, the Hall element  58   b  being a magnetic sensor is used as the magnetic-pole position detection element, and the Hall element  58   b  is packaged together with an IC that converts an output signal thereof to a digital signal and is configured as a Hall IC, and the Hall IC is surface-mounted on the substrate  58 . By using the Hall IC surface-mounted on the substrate  58  to detect leakage flux of the resin magnet  68  from the axial end face (the surface opposite to the magnetic-pole position detection element) of the resin magnet  68 , the machining cost and the like of the substrate  58  can reduce the production cost of the pump  10 , as compared to a case where the Hall element  58   b  is fixed to the substrate  58  by a Hall element holder (not illustrated) so as to detect the main magnetic flux of the resin magnet  68  from the side surface of the resin magnet  68 . In contrast, in the conventional arts, in order to detect the magnetic pole position, it has been necessary to assemble the magnetic-pole position detection element on the substrate by using a magnetic-pole position detection-element holder so that the magnetic-pole position detection element (the magnetic sensor) is positioned on an outer periphery of a position detection magnet. Therefore, there have been problems in ensuring an installation space of the magnetic-pole position detection element so as to increase the machining cost due to an increase in the number of components such as the magnetic-pole position detection-element holder. 
     Although not illustrated, as another modification of the resin magnet  68 , the position of the gate  68   c , to which the material of the resin magnet  68  is supplied, can be arranged at the magnetic pole center. In this case, the gate  68   c  can be provided in the protrusion  68   e . The resin magnet  68  according to this modification can improve orientation accuracy of the resin magnet  68  by positioning the gate  68   c  at the magnetic pole center, thereby enabling the quality of the pump  10  to be improved. 
     Integral molding of the rotor  60  of the pump motor by the thermoplastic resin is described next. The resin magnet  68  is an example of the magnet. 
     The die for integrally molding the resin magnet  68  and the sleeve bearing  66  includes an upper die and a lower die (not illustrated). The sleeve bearing  66  is first set in the lower die. The sleeve bearing  66  can be set to the die without matching the circumferential direction, because the cross-sectional shape is symmetrical. The sleeve bearing  66  includes a plurality of protrusions  66   a  (refer to  FIG. 12 ) on the outer periphery thereof, but the position of the protrusions  66   a  is not specifically limited. Therefore, an operation process is simplified so as to improve the productivity, and the production cost can be reduced. 
     When the sleeve bearing  66  is set in the lower die, the inner diameter of the sleeve bearing  66  is held in a sleeve-bearing insertion portion (not illustrated) provided in the lower die, thereby ensuring the accuracy of concentricity of the sleeve bearing  66  and the resin magnet  68  to be set in a subsequent process. 
     After the sleeve bearing  66  is set in the lower die, the resin magnet  68  is set in the lower die by fitting the tapered notches  68   b  provided on the inner peripheral edge of one of the end faces (the end face opposite to the impeller attachment unit  67   a  in the state of the rotor  60 ) to the positioning protrusions (not illustrated) provided in the lower die. In the example illustrated in  FIG. 15 , there are eight notches  68   b . Four notches among these, provided substantially at an interval of 90 degrees, are fitted to the positioning protrusions (not illustrated) in the lower die, thereby ensuring the accuracy of concentricity of the sleeve bearing  66  and the resin magnet  68 . The reason why the eight notches  68   b  are provided is to improve the workability at the time of setting the resin magnet  68  in the lower die. 
     Further, the magnet pressing parts (not illustrated) provided in the upper die are axially pressed against the substantially horn-shaped protrusions  68   a  formed on an inner peripheral edge of the other end face (the end face on the side of the impeller attachment unit, and in the state of the rotor  60 ) of the resin magnet  68 . Accordingly, the positioning relation between the sleeve bearing  66  and the resin magnet  68  is secured. 
     In the example illustrated in  FIG. 14 , three substantially horn-shaped protrusions  68   a  are provided on the inner periphery of the resin magnet  68 ; and a die installation surface (a portion pressed by the die) of the protrusion  68   a  is exposed after integrally being molded. The reason why there are three protrusions  68   a  is to secure the positioning accuracy of the resin magnet  68  and ensure a flow passage of the thermoplastic resin to be used for integral molding, thereby alleviating the molding condition at the time of integral molding to improve the productivity. 
     Even when there is a gap between an insertion portion (not illustrated) of the resin magnet  68  in the lower die and the outer diameter of the resin magnet  68 , an inner-diameter pressing part (the positioning protrusion) provided in the lower die ensures the concentricity, and the position relation and the concentricity between the sleeve bearing  66  and the resin magnet  68  can be ensured by sandwiching these by the upper die and the lower die, thereby enabling the quality of the pump  10  to be improved. 
     In contrast, by making a gap between the insertion portion (not illustrated) of the resin magnet  68  in the lower die and the outer diameter of the resin magnet  68 , the workability at the time of setting the resin magnet  68  in the die is improved so as to reduce the production cost. 
     After the resin magnet  68  and the sleeve bearing  66  are set in the die, the thermoplastic resin such as PPE (polyphenylene ether) is injected into the die, thereby forming the rotor unit  60   a . During the injection, the notches  68   b  ( FIG. 15 ) of the resin magnet  68  that are not pressed by the die, which are the four notches  68  and the protrusions  68   e  provided on the end face on the side of the magnetic-pole position detection element of the resin magnet  68 , are embedded in the resin portion  67  of the thermoplastic resin so as to become a transmitting portion of the rotation torque. Further, through holes  69  and the protrusions  68   e  are embedded in the resin portion  67  of the thermoplastic resin, thereby firmly holding the resin magnet  68 . 
     After the resin magnet  68  and the sleeve bearing  66  have been integrally molded by using the thermoplastic resin (the resin portion  67 ), at the time of magnetizing the resin magnet  68 , highly accurate magnetization can be performed by using the notches  67   d  (four notches in  FIG. 11 ) formed on the inner periphery of the one end face in the axial direction of the resin magnet  68  for positioning at the time of magnetization. 
     The manufacturing process of the pump  10  is described next with reference to  FIG. 20 .  FIG. 20  illustrates the manufacturing process of the pump  10 . 
     (1) Step 1: The annular stator iron core  54  is formed by punching an electromagnetic steel plate having a thickness of about 0.1 millimeter to 0.7 millimeter in a belt-like form and then being laminated by swaging, welding, or bonding. The sleeve bearing  66  is made as well. In addition, the resin magnet  68  having the through holes  69  extending in the axial direction from the end face on the side of the magnetic-pole position detection element (the Hall element  58   b ) to the end face on the side of the impeller attachment unit are molded.
 
(2) Step 2: The stator iron core  54  is wound with a winding wire. The insulation part  56  using the thermoplastic resin such as PBT (polybutylene terephthalate) is applied to the teeth of the annular stator iron core  54  connected with the thin connection part. The concentratedly wound coil  57  is wound around the teeth applied with the insulation part  56 . For example, if 12 (twelve) concentratedly wound coils  57  are connected, three-phase single Y-connection windings are formed. Because the winding is three-phase single Y-connection, the terminals  59  (the supply terminals to which power is supplied and the neutral terminal) of the stator  47 , to which the coils  57  of respective phases (a U phase, a V phase, and a W phase) are connected, are assembled on the connection side of the insulation part  56 . The substrate  58  is manufactured as well. The substrate  58  is held between the substrate pressing component  95  and the insulation part  56 . The IC that drives a motor (for example, a brushless DC motor), the Hall element  58   b  that detects the position of the rotor  60 , and the like are mounted on the substrate  58 . Further, the substrate  58  is fitted with the lead-wire leading component  61  that leads out the lead wire  52  at the notched portion near the outer periphery thereof. The rotor unit  60   a  is manufactured as well. In the rotor unit  60   a , the ring-shaped (cylindrical or annular) resin magnet  68  molded by using the pellet formed by kneading a magnetic powder, for example, ferrite powder and resin and the cylindrical sleeve bearing  66  (for example, made of carbon) provided inside of the resin magnet  68  are integrally molded by using the resin such as PPE (polyphenylene ether); and the through hole  69  is embedded in the resin. The impeller  60   b  is also molded. The impeller  60   b  is molded by using the thermoplastic resin such as PPE (polyphenylene ether).
 
(3) Step 3: The substrate  58  is to be assembled on the stator  47 . The substrate  58  fitted with the lead-wire leading component  61  is fixed to the insulation part  56  by the substrate pressing component  95 . The impeller  60   b  is also assembled on the rotor unit  60   a  by ultrasonic welding or the like. The cup-shaped partition component  90  is also molded. The shaft  70  and the thrust bearing  71  are manufactured. The shaft  70  is manufactured from, for example, SUS. The thrust bearing  71  is manufactured from, for example, ceramics.
 
(4) Step 4: The substrate  58  is soldered. The terminals  59  (the supply terminals to which power is supplied and the neutral terminal) are soldered to the substrate  58 . The pilot hole component  81  is molded. The casing  41  is also molded. The casing  41  is molded by using a thermoplastic resin such as PPS (polyphenylene sulfide). The rotor  60  and the like are assembled into the cup-shaped partition component  90 .
 
(5) Step 5: After having manufactured the stator assembly  49  by assembling the pilot hole component  81  in the stator  47 , the stator assembly  49  is mold-formed so as to manufacture the molded stator  50 . The casing  41  is fixed to the cup-shaped partition component  90  to assemble the pump unit  40 . The tapping screws  160  are also manufactured.
 
(6) Step 6: The pump  10  is assembled. The pump unit  40  is assembled on the molded stator  50  and fixed with the tapping screws  160  (refer to  FIG. 2 ).
 
       FIG. 21  is a conceptual diagram illustrating a circuit of a refrigeration cycle device using the refrigerant-water heat exchanger  2 . The heat-pump type water heater  300  described above is an example of the refrigeration cycle device using the refrigerant-water heat exchanger  2 . 
     The refrigeration cycle device using the refrigerant-water heat exchanger  2  includes, for example, an air conditioner, a floor heating device, or a hot water dispenser. The pump  10  according to the present embodiment constitutes a water circuit of a device using the refrigerant-water heat exchanger  2 , and circulates water (hot water) cooled or heated by the refrigerant-water heat exchanger  2  in the water circuit. 
     The refrigeration cycle device illustrated in  FIG. 21  includes the refrigerant circuit having a compressor  1  (for example, a scroll compressor or a rotary compressor) that compresses the refrigerant, the refrigerant-water heat exchanger  2  that performs heat exchange between the refrigerant and water, the evaporator  4  (heat exchanger), and the like. The refrigeration cycle device also includes the water circuit having the pump  10 , the refrigerant-water heat exchanger  2 , a load  20 , and the like. 
     As described above, according to the present embodiment, the following effects can be achieved. 
     (1) The resin magnet  68  integrally molded with the sleeve bearing  66  in the rotor unit  60   a  includes the plurality of through holes  69 , each extending in the axial direction from the end face on the side of the magnetic-pole position detection element toward the side of the impeller attachment unit and each substantially on the same circumference; these through holes  69  are embedded in the thermoplastic resin when integrally molded from the thermoplastic resin; and the resin magnet  68  is firmly held by the thermoplastic resin. Accordingly, cracking of the magnets due to the thermal shock associated with the cold/hot water cycle can be reduced.
 
(2) Because the resin magnet  68  is firmly held by the thermoplastic resin without covering the outer peripheral surface of the resin magnet  68  with the thermoplastic resin, the resin magnet  68  and the stator  47  can be arranged close to each other, thereby enabling the performance of the pump  10  to improve.
 
(3) Because the resin magnet  68  is firmly held by the thermoplastic resin without covering the outer peripheral surface of the resin magnet  68  with the thermoplastic resin, the amount of thermoplastic resin used can be reduced, and the pump  10  can be manufactured at a lower cost.
 
(4) Because the resin magnet  68  is firmly held by the thermoplastic resin without covering the outer peripheral surface of the resin magnet  68  with the thermoplastic resin, irregularities, which cause an increase of fluid friction losses, are not formed on the outer peripheral surface of the rotor  60 , thereby enabling the performance of the pump  10  to improve.
 
(5) The through holes  69  provided in the resin magnet  68  are positioned between the magnetic poles formed in the rotor  60 , so that a decrease of the magnetic force is much reduced and a performance decrease of the pump  10  can be reduced.
 
(6) The resin magnet  68  is provided with the gates  68   c , to which the material of the resin magnet  68  is supplied, on the end face opposite to the magnetic-pole position detection element (the Hall element  58   b ); and because the position of the gate  68   c  is at the center of the magnetic pole, the orientation accuracy of the resin magnet  68  can be improved.
 
(7) The plurality of protrusions  68   e  are formed, each on the same circumference substantially at a regular interval in the circumferential direction and on the end face opposite to the magnetic-pole position detection element (the Hall element  58   b ) of the resin magnet  68 , and these protrusions  68   e  are arranged at the center of the magnetic poles. Accordingly, the magnetic force is improved, thereby enabling the performance of the pump  10  to be improved.
 
(8) The hollow portion of the resin magnet  68  has a straight shape from the end face where the protrusions  68   a  are formed to the substantially axial center position; and has a drawn-out taper shape from the end face opposite to the end face where the protrusions  68   a  are formed to the substantially axial center position, thereby enabling the productivity of the resin magnet  68  to be improved.
 
(9) When the pump  10  is applied to the refrigeration cycle device using the refrigerant-water heat exchanger  2  (for example, an air conditioner, a floor heating device, or a hot water dispenser), the performance and quality of the refrigeration cycle device can be improved and cost can be reduced, due to the improvement of the performance, quality, and the productivity of the pump  10 .
 
     Second Embodiment 
       FIG. 22  is a cross-sectional view of the rotor unit  60   a  according to the present embodiment, which corresponds to  FIG. 9  described in the first embodiment.  FIG. 23  is a cross-sectional view of the resin magnet  68  according to the present embodiment, which corresponds to  FIG. 13  described in the first embodiment. In  FIGS. 22 and 23 , like reference signs denote like constituent elements in  FIGS. 9 and 13 . In the present embodiment, the through hole  69  according to the first embodiment is replaced with a through hole  69   a  having a shape as illustrated in  FIGS. 22 and 23 . Other configurations are the same as those of the first embodiment. 
     As illustrated by  FIGS. 22 and 23 , with a position (gradient changing position) that is a set depth from the end face of the side with the magnetic-pole position detection element (the Hall element  58   b ) as a reference point, the inner diameter of the through hole  69  slopes, with increasing gradients (diameters) (D1, D2), respectively, from the reference point towards both the magnetic-pole position detection element side and the impellor attachment unit side. That is, the cross-sectional shape of the through hole  69   a  is such that the external shape of the through hole  69   a  on the opposite sides has the gradient D1 with respect to the axial direction from the gradient changing position to the end face on the side of the magnetic-pole position detection element so that the inner diameter of the through hole  69   a  increases toward the side of the magnetic-pole position detection element; and the external shape of the through hole  69   a  on the opposite sides has the gradient D2 with respect to the axial direction from the gradient changing position to the end face on the side of the impeller attachment unit so that the inner diameter of the through hole  69   a  increases toward the side of the impeller attachment unit. 
     Further, by defining a gradient angle and a length of the through hole  69   a  so that the magnet volume on the side of the magnetic-pole position detection element becomes larger than that on the side of the impeller attachment unit, which is with reference to the center position of the resin magnet  68  in the axial direction (a structure center position in the axial direction), the center of magnetic flux in the axial direction of the resin magnet  68  can be shifted by a predetermined distance toward the side of the magnetic-pole position detection element. By shifting the center positions of the magnetic flux in the axial direction of the rotor  60  and the stator  47  toward the side of the magnetic-pole position detection element, even in a case where the center position of the resin magnet  68  in the axial direction and the center position of the stator  47  in the axial direction are substantially the same, a propulsive force from the side of the magnetic-pole position detection element toward the side of the impeller attachment unit is generated in the rotor  60  so that the center positions of the magnetic flux in the axial direction of the rotor  60  and the stator  47  become substantially the same. Due to such a propulsive force of the rotor  60  pressing the rotor  60  against the casing  41  via the thrust bearing  71 , fluctuations in the position in the axial direction of the rotor  60  caused by pressure pulsation of the fluid due to the action of the impeller  60   b  can be reduced, thereby enabling the quality of the pump  10  to improve. 
     Instead of providing the gradient in the through hole  69   a , by changing the inner diameter of the through hole  69   a  on the basis of the reference position at the predetermined depth from the end face of the resin magnet  68  on the side of the magnetic-pole position detection element, the center position of the magnetic flux in the axial direction of the resin magnet  68  can be shifted toward the side of the magnetic-pole position detection element by a predetermined distance (not illustrated). 
     According to the present embodiment, in addition to the effects of (1) to (9) described in the first embodiment, the following effects can be achieved. 
     (10) The through hole  69   a  provided in the resin magnet  68  has a gradient by which the inner diameter of the through hole  69   a  increases both toward the side of the magnetic-pole position detection element and toward the side of the impeller attachment unit, which is with reference to the reference position at the predetermined depth (the gradient changing position) from the end face on the side of the magnetic-pole position detection element (the Hall element  58   b ). Accordingly, adhesion to the die can be prevented, thereby enabling the productivity of the resin magnet  68  to improve.
 
(11) By defining the gradient angle and the length of the through hole  69   a  so that the magnet volume on the side of the magnetic-pole position detection element becomes larger than the magnet volume on the side of the impeller attachment unit, which is with reference to the center position in the axis direction of the resin magnet  68 , the center of the magnetic flux in the axial direction of the resin magnet  68  is shifted by the predetermined distance toward the side of the magnetic-pole position detection element. Accordingly, the propulsive force from the side of the magnetic-pole position detection element toward the side of the impeller attachment unit is generated in the rotor  60  to press the rotor  60  against the casing  41  via the thrust bearing  71 , thereby enabling the rotor  60  to reduce fluctuations of the position in the axial direction caused by the pulsation of the fluid due to the action of the impeller  60   b  and enabling the quality of the pump  10  to be improved.
 
     INDUSTRIAL APPLICABILITY 
     As explained above, the present invention is useful as a pump, a method for manufacturing a pump, and a refrigeration cycle device. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  compressor,  2  refrigerant-water heat exchanger,  3  decompression device,  4  evaporator,  5  pressure detection device,  6  fan motor,  7  fan,  8  boiling-up temperature detection unit,  9  feed-water temperature detection unit,  10  pump,  11  operating unit, tank-unit control unit,  13  heat-pump-unit control unit,  14  hot water tank,  15  refrigerant pipe,  16  hot-water circulating pipe,  17  ambient-air temperature detection unit,  20  load,  31  bathwater-reheating heat exchanger,  32  bathwater circulating device,  33  mixing valve,  34  in-tank water-temperature detection unit,  35  reheated water-temperature detection unit,  36  mixed water-temperature detection unit,  37  bathwater reheating pipe,  40  pump unit, casing,  42  intake,  43  discharge outlet,  44  boss,  44   a  screw hole,  46  shaft support portion,  47  stator,  49  stator assembly,  50  molded stator,  52  lead wire,  53  mold resin,  54  stator iron core,  54   a  groove,  56  insulation part,  57  coil,  58  substrate,  58   a  IC,  58   b  Hall element, terminal,  60  rotor,  60   a  rotor unit,  60   b  impeller,  61  lead-wire leading component,  63  flat pump-unit installation surface,  66  sleeve bearing,  66   a  protrusion, resin portion,  67   a  impeller attachment unit,  67   b  depression,  67   c  impeller positioning hole,  67   d  notch,  67   e  gate,  68  resin magnet,  68   a  protrusion,  68   a - 1  convex portion,  68   b  notch,  68   c  gate,  68   e  protrusion,  68   f  rotor-position detecting magnetic-pole portion,  69 ,  69   a  through hole,  70  shaft,  71  thrust bearing,  80  O-ring, pilot hole component,  82  die pressing part,  83  protrusion,  84  pilot hole,  85  leg part,  85   a  protrusion,  87  connection part,  90  cup-shaped partition component,  90   a  cup-shaped partition wall portion,  90   b  flange portion,  90   c  circular O-ring housing groove,  90   d  hole,  92  rib,  94  shaft support portion,  95  substrate pressing component,  95   a  protrusion,  100  heat pump unit,  160  tapping screw,  200  tank unit,  300  heat-pump type water heater