Abstract:
An electrically driven pump is provided, which includes an impeller. The impeller includes an upper plate, blades and a lower plate. The blades are formed on a lower surface of the upper plate, the blades include first blades and second blades, and a length of each of the first blades is greater than a length of each of the second blades. The first blades are uniformly distributed along a circumference of the upper plate. The first blades and the second blades are distributed alternately in the circumferential direction. The first blades each include a first head portion and a first tail portion, the second blade includes a second head portion and a second tail portion, and the first tail portion and the second tail portion are aligned with outer edge of the upper plate. The impeller arranged in such manner facilitates the improvement of hydraulic efficiency and lift.

Description:
CROSS REFERENCE OF RELAYED APPLICATION 
       [0001]    The present application claims the priority to Chinese Patent Application No. 201510393337.8, titled “IMPELLER, CENTRIFUGAL PUMP, ELECTRICALLY DRIVEN PUMP”, filed on Jul. 06, 2015, with the State Intellectual Property Office of the People&#39;s Republic of China, the content of which is incorporated herein by reference in its entirety. 
       FIELD 
       [0002]    This application relates to a component in a heat circulating system. 
       BACKGROUND 
       [0003]    In recent decades, electrically driven pumps have been widely used in heat circulating systems. Currently, the heat circulating systems are developed in a trend of high performance, and compactification, accordingly, the electrically driven pump has a limited mounting space, and has requirements for high performance. Since the electrically driven pump has a small overall dimension and a small volume, the electrically driven pump includes an impeller, a diameter of the impeller is required to be small, in this case, a conventional impeller can hardly meet the requirements for high lift and high efficiency at low specific speed and low flow rate. 
         [0004]    Therefore, it is necessary to improve the conventional technology, to address the above technical issues. 
       SUMMARY 
       [0005]    An object of the present application is to provide an electrically driven pump, which may achieve the required flow rate and lift at a low speed, and may achieve a high hydraulic efficiency. 
         [0006]    To achieve the above objects, the following technical solutions are adopted in the present application. An electrically driven pump includes a rotor assembly, a stator assembly, and a partition. The rotor assembly and the stator assembly are partitioned by the partition. The rotor assembly includes an impeller, the impeller includes an upper plate, blades, and a lower plate, and the blades are provided between the upper plate and the lower plate. The upper plate includes an upper surface and a lower surface, the blades and the upper plate are integrally formed by injection molding, and the blades are located on the lower surface of the upper plate. The blades include first blades and second blades, and each of the first blades and the second blades includes a camber, or a combination of two or more than two cambers, or a combination of a camber and a plane. A length of each of the first blades is greater than a length of each of the second blades, the first blades are uniformly distributed along a circumference of the upper plate, and the second blades are uniformly distributed along the circumference of the upper plate. A number of the first blades is the same as a number of the second blades, and the first blades and the second blades are distributed alternately along the circumferential direction of the upper plate. Each of the first blades includes a first head portion and a first tail portion, and each of the second blades includes a second head portion and a second tail portion. An outer edge of the upper plate defines a first circumference with a diameter of Φ 1 , the second head portions of the second blades are located on a second circumference with a diameter of Φ 2 , and the diameter Φ 2  of the second circumference ranges 0.6 times to 0.75 times of the diameter Φ 1  of the first circumference. 
         [0007]    Compared with the conventional technology, the electrically driven pump according to the present application includes the impeller, the impeller includes the upper plate, the blades and the lower plate, and the blades are arranged between the upper plate and the lower plate. The blades include the first blades and the second blades, the outer edge of the upper plate defines the first circumference with a diameter of Φ 1 , the head portions of the second blades are located on the second circumference with a diameter of Φ 2 , and the diameter of the second circumference ranges from 0.6 times to 0.7 times of the diameter of the first circumference. The impeller arranged in such manner facilitates achieving a required flow rate and lift by the electrically driven pump, and facilitates the improvement of a hydraulic efficiency of the electrically driven pump. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a schematic sectional view showing the structure of an electrically driven pump according to an embodiment of the present application; 
           [0009]      FIG. 2  is a schematic exploded view showing the structure of a rotor assembly in  FIG. 1 ; 
           [0010]      FIG. 3  is a schematic perspective view showing the structure of the rotor assembly in  FIG. 1 ; 
           [0011]      FIG. 4  is a schematic orthographic view showing the structure of the rotor assembly in  FIG. 2  viewed from a top; 
           [0012]      FIG. 5  is a schematic sectional view showing the structure of the rotor assembly in  FIG. 2 ; 
           [0013]      FIG. 6  is a schematic front view showing the structure of a first part in  FIG. 2 ; 
           [0014]      FIG. 7  is a schematic perspective view showing the structure of a second part in  FIG. 2 ; and 
           [0015]      FIG. 8  is a schematic top view showing the structure of the second part in  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    The present application is further described in conjunction with drawings and embodiments hereinafter. 
         [0017]      FIG. 1  is a schematic view showing the structure of an electrically driven pump  100 . The electrically driven pump  100  includes a first housing  10 , a partition  20 , a second housing  30 , a shaft  40 , a rotor assembly  50 , a stator assembly  60 , a circuit board  70  and a heat dissipating assembly  80 . An inner chamber of the electrically driven pump includes a space defined by the first housing  10  and the second housing  30 , and the partition  20  divides the inner chamber of the electrically driven pump into a first chamber  91  and a second chamber  92 . The first chamber  91  allows working medium to flow through, and the rotor assembly  50  is arranged in the first chamber  91 . No working medium flows through the second chamber  92 , and the stator assembly  60  and the circuit board  70  are arranged in the second chamber  92 . The shaft  40  is fixed to the partition  20  by injection molding. The rotor assembly  50  is rotatable about the shaft  40 . The rotor assembly  50  is separated from the stator assembly  60  by the partition  20 . The stator assembly  60  is electrically connected to the circuit board  70 . The circuit board  70  is connected to an external circuit by a socket-connector. The heat dissipating assembly  80  is configured to transfer and dissipate heat generated by the circuit board  70 , and the heat dissipating assembly  80  is fixedly mounted to the second housing  30 . In this embodiment, the electrically driven pump  100  is an inner rotor type electrically driven pump, and the inner rotor type electrically driven pump is referred to as a pump in which the rotor assembly  50  is arranged to be closer to the shaft  16  than the stator assembly  60  if the shaft  40  is taken as a central axis. In this embodiment, the shaft  40  is arranged to be fixed with respect to the partition  20 , and the rotor assembly  50  is rotatable with respect to the shaft  40 . Of course, the shaft  40  may also rotate with respect to the partition  20  by means of the shaft sleeve, and the rotor assembly  50  may be fixed to the shaft  40  and rotate along with the shaft  40 . 
         [0018]      FIGS. 2 to 9  are schematic views showing the structure of the rotor assembly  50 . Referring to  FIG. 2 , the rotor assembly  50  includes two parts of injection molded members, respectively a first part  51  and a second part  52  which are fixed to each other by welding. The first part  51  includes an upper plate  11  and blades  12 , and the first part  51  is integrally formed by injection molding. In an embodiment, the material for the injection molding is a mixture including polyphenylene sulfide (abbreviated as PPS) and glass fiber. The second part  52  includes a permanent magnet  21 , and a lower plate  13 . The second part  52  is formed by injecting molding using a mixed material containing the PPS and carbon fiber and taking the permanent magnet  21  as an injection molding insert. In addition, the injection molding material may also be other thermoplastic materials having a relatively good mechanical performance. Referring to  FIG. 3 , the rotor assembly  50  includes an impeller  1  and a rotor  2  according to function. The impeller  1  includes the upper plate  11 , the blades  12  and the lower plate  13 . The rotor  2  includes the permanent magnet  21 . In this embodiment, the permanent magnet  21  is substantially of an annular structure, and the permanent magnet  21  is formed by injection molding or sintering, and of course, the rotor  2  may also be in other structural forms. In this embodiment, portions of the impeller  1  except the upper plate  11  and the blades  12  are integrally formed with the permanent magnet  21  by injection molding, and the integral piece formed by injection molding is used in the electrically driven pump. The impeller  1  may also be formed separately and may be used in other centrifugal pumps, and is not limited to the electrically driven pump, and is also not limited to be integrally formed with the rotor  2 . 
         [0019]    Referring to  FIG. 3 , the impeller  1  includes an inlet  15 , the upper plate  11 , the blades  12 , the lower plate  13 , and an outlet  14 . The blades  12  are arranged between the upper plate  11  and the lower plate  13 . The inlet  15  of the impeller  1  is formed by the upper plate  11 . Multiple outlets  14  of the impeller  1  are formed at an outer periphery of the upper plate  11  between adjacent blades  12  and between the upper plate  11  and the lower plate  13 . Multiple impeller passages are formed between adjacent blades  12 , and each of the impeller passages is in communication with the inlet  15  and one of the outlets  14  of the impeller  1 . An upper side and a lower side of each of the impeller passages are closed by the upper plate  11 , the lower plate  13 , and side walls of blades at the two lateral sides of the impeller passage. 
         [0020]    Referring to  FIGS. 3, 5, and 6 , the upper plate  11  is substantially of an annular shape. The upper plate  11  includes a plane portion  111  and a camber portion  112 . The plane portion  111  includes an upper plane portion  1111  and a lower plane portion  1112 . The camber portion  112  includes a first camber portion  1121  and a second camber portion  1122 . The first camber portion  1121  is smoothly transited to the upper plane portion  1111 , the second camber portion  1122  is smoothly transited to the lower plane portion  1112 , and the inlet  15  of the impeller  1  is formed by encircling of the camber portion  112 . The blades  12  are integrally formed with the lower plane portion  1112 , or the lower plane portion  1112  and the second camber portion  1122 , of the upper plate  11  by injection molding. Referring to  FIG. 3 , at a side wall of the inlet  15  of the impeller  1 , the impeller  1  includes a vertical portion  113  tangential to the side wall of the inlet  15  of the impeller  1 , actually, the vertical portion  113  is a partial connecting portion where the upper plate  11  is connected to the blades  12 , thus facilitating demolding of the first part  51  of the impeller  1 . In this embodiment, the plane portion  111  is set at a certain angle with respect to the horizontal plane, and the blades  12  are arranged to be substantially perpendicular to the horizontal plane. An outer edge of the upper plate  111  defines substantially a first circumference with a diameter of Φ 1 , and a diameter of the impeller is equal to the diameter of the first circumference, and is also equivalent to an outer diameter of a circle defined by tail portions of outer edges of the blades  12 . 
         [0021]    Referring to  FIGS. 2 and 6 , the blades  12  include first blades  121  and second blades  122 . The first blades  121  and the second blades  122  are each in a circular-arc shape. A length of each of the first blades  121  is greater than a length of each of the second blades  122 . The first blades  121  are distributed at equal intervals along a circumference of the impeller  1 , and the second blades  122  are distributed at equal intervals along the circumference of the impeller  1 . 
         [0022]    The number of the first blades  121  is the same as the number of the second blades  122 . The first blades  121  and the second blades  122  are distributed alternately along the circumference of the impeller  1 , i.e., each of the second blades  122  is arranged between adjacent first blades  121 . Each of the first blades  121  and the second blades  122  may each include a camber, or a combination of two or more than two cambers, or a combination of a camber and a plane. 
         [0023]    Referring to  FIG. 6 , the first blades  121  are formed integrally with the lower plane portion  1112  and the second camber portion  1122  of the upper plate  11  by injection molding. Each of the first blades  121  includes a first segment  3  integrally formed with the second camber portion  1122  by injection molding, and a second segment  4  integrally formed with the lower plane portion  1112  by injection molding. The first segment  3  includes a head portion  31 , a first bottom  32 , a first concave side  33 , and a first convex side  34 . The second segment  4  includes a second bottom  42 , a second concave side  43 , a second convex side  44 , and a tail portion  45 . The head portion  31  protrudes into the inlet  15  of the impeller  1 . The head portion  31  is a start end of the first blade  121 , and the tail portion  45  is a terminal end of the first blade  121 . An arc length between the head portion  31  and the tail portion  45  is the length of the first blade  121 . In this embodiment, the first concave side  33  and the second concave side  43  form a first side of the first blade  121 . The first convex side  34  and the second convex side  44  form a second side of the first blade  121 . The head portion  31  is a first head of the first blade  121 , and the tail portion  45  is a first tail portion of the first blade  121 . On the first circumference, a first circular arc with a length of L 1  is defined between intersections of, the second concave sides  43  of adjacent first blades  121 , with the first circumference. The length L 1  of the first circular arc is equal to a length of each circular arc defined by equally dividing the first circumference into parts with the number of the first blades  121 . In this embodiment, the number of the first blades  121  is five, and the length L 1  of the first circular arc is equal to a length of each circular arc defined by equally dividing the first circumference into five parts. 
         [0024]    Referring to  FIG. 2 , a portion where the head portion  31  is located is a flow guiding part of the first blade  121 . The working medium enters into the impeller  1  through the inlet  15  of the impeller  1  and is guided into a circulating passage between adjacent first blades  121  via the head portion  31 , and the head portion  31  is fixed to an inner side wall of the inlet  15  by injection molding. The first segment  3  further includes a connecting side  1216  arranged between the head portion  31  and the first concave side  33 . A distance from the connecting side  1216  to the first convex side  34  is smaller than a distance from the first concave side  33  to the first convex side  34 . In this way, the connecting side  1216  allows a thickness of each of the first blades  121  at a section corresponding to the connecting side  1216  to be decreased, thus, a gap between the first blades  121  at the portion from the head portion  31  to a terminal position of the connecting side  1216  may be increased, which may reduce a flowing resistance to the working medium, and allows the working medium to smoothly flow. 
         [0025]    Referring to  FIGS. 2 and 3 , the head portion  31  protrudes into the inlet  15  of the impeller  1 . A straight line is defined by passing through a fixing point  311  at which the first blade  121  is fixed to the side wall of the impeller inlet  15  and being in parallel with a center line of the side wall of the inlet  15  of the impeller  1 , an included angle between the head portion  31  and the straight line is a front inclination angle  03  ranging from  20  degrees to  50  degrees. A free end of the head portion  31  inclines to a central axis direction of the impeller inlet  15  by 20 degrees to 50 degrees, in this way, the part where the head portions  31  are located can better restrict flowing of the working medium. 
         [0026]    A thickness of each of the first blades  121  is represented by ε 1 , and the thickness ε 1  of the first blade  121  is referred to as a vertical distance between the first side and the second side of the first blade. In this embodiment, considering that the material for forming the blade by injection molding has a certain brittleness, the first blade  121  may be fractured, broken or damaged if it is too thin, therefore, the value of the thickness ε 1  of the first blade according to the present application is set relatively large. In this embodiment, the thickness ε 1  of the first blade generally ranges from 0.8 mm to 2 mm. In this embodiment, for facilitating demolding, the first side and the second side are provided with small draft angles respectively, since the draft angles are very small, a height difference generated by the draft angles may be neglected when compared to the height of the first blade  121   
         [0027]    Referring to  FIG. 6 , on the first circumference, at an intersection of the second concave side  43  or an extending side of the second concave side of the first blade  121  with the first circumference, an included angle between a tangential line of the second concave side  43  or the extending side of the second concave side  43 , and a tangential line of the first circumference at the intersection is a first included angle β 1  of the first blade  121 . The first included angle β 1  of the first blade  121  ranges from 20 degrees to 60 degrees. In this embodiment, the impeller  1  of the electrically driven pump  100  is a low specific speed centrifugal impeller, and a large blade angle is generally configured to reduce a frictional loss of disk as much as possible, thus ensuring the efficient operation of the electrically driven pump. However, the blade angle β 1  that is large may adversely affect the performance stability of the impeller, thus in order to acquire a stable performance curve and preventing overloading, for the structure of the impeller  1  according to this embodiment, the first included angle β 1  of the first blade  121  according to the present application ranges from 20 degrees to 60 degrees. 
         [0028]    Referring to  FIGS. 2 and 6 , each of the first blades  121  includes a bottom, and the bottom includes the first bottom  32  and the second bottom  42 . From a central portion of the upper plate to an edge of the upper plate, a distance from the second bottom  42  to the upper plate  11  gradually decreases. On the first circumference, the tail portion  45  is arranged to be aligned with an outer edge of the upper plate  11  of the impeller. The tail portion  45  is a small section of a cylindrical surface, or the tail portion  45  is a portion of a cylindrical surface defined by extending the outer edge of the upper plate  11 . The tail portion  45  connects the second concave side  43  and the second convex side  44  at an end of the first blade  121 . The tail portion  45  has a height which is a smallest height of the first blade  121 , and the height of the first blade  121  at the tail portion  45  is defined as an outlet height H 1  of the first blade  121 . The bottom of the first blade  121  is provided with a connecting structure fixed to the lower plate  13 . The connecting structure includes a cylindrical protrusion  321  and protruding ribs  322 . A height of each of the protruding ribs  322  protruded is smaller than a height of the cylindrical protrusion  321 , and the protruding ribs  322  are arranged at intervals along the bottom. Each first blade  121  is provided with one cylindrical protrusion  321  and multiple protruding ribs  322 . The free end of the first blade is namely the bottom of the first blade. 
         [0029]    Referring to  FIG. 6 , the second blade  122  is fixed to the plane portion  111  of the upper plate  11  by injection molding. The second blade  122  starts from a second circumference with a diameter of Φ 2 , and terminates at the first circumference with the diameter of Φ 1 , and the diameter Φ 2  of the second circumference ranges from 0.6 times to 0.75 times of the diameter Φ 1  of the first circumference. The second blade  122  includes a front end  1221 , a concave side  1222 , a convex side  1223 , a rear end  1224  and a bottom  1225  of the second blade. The front end  1221  is arranged at the second circumference with the diameter of Φ 2 , and the rear end  1224  is arranged at the first circumference with the diameter of Φ 1 . On the first circumference, at an intersection of the concave side  1222  or an extending side of the concave side with the first circumference, an included angle between a tangential line of the concave side  1222  or the extending side of the concave side, and a tangential line of the first circumference is a second included angle β 2  of the second blade  122 . In this embodiment, the front end  1221  is a second head portion of the second blade  122 , and the rear end  1224  is a second tail portion of the second blade  122 , the concave side  1222  is a third side of the second blade  122 , and the convex side  1223  is a fourth side of the second blade  122 . The second included angle β 2  of the second blade  122  is smaller than or equal to the first included angle β 1  of the first blade  121 . In this embodiment, and the second included angle β 2  of the second blade  122  is smaller than the first included angle β 1  of the first blade  121  by 3 degrees to 10 degrees. Except portions at the front end  1221  and the rear end  1224 , a thickness ε 2  of the second blade ranges from 0.6 times to 1 times of the thickness ε 1  of the first blade, and if the central axis of the inlet of the impeller is taken as a center of circle, a height of the second blade is smaller than or equal to a height of the first blade at the same portion of the circle. The free end of the second blade is namely the bottom of the second blade. 
         [0030]    Referring to  FIGS. 2 and 6 , from the front end  1221  to the rear end  1224 , a distance from the bottom  1225  of the second blade  122  to the lower surface of the upper plate gradually decreases, and is the smallest at the first circumference. An outlet height H 2  of the second blade is defined as the smallest distance from the second blade bottom  1225  to the lower surface of the upper plate at the first circumference. In this embodiment, a height of the second blade is smaller than a height of the first blade at the same position of the circle, and the outlet height H 2  of the second blade is smaller than the outlet height H 1  of the first blade. Thus, after the impeller is assembled, a certain gap or a small gap is formed between the second blade bottom  1225  and the lower plate  13 . On the first circumference, a second circular arc with a length of L 2  is defined between a tangential line of the concave side  1222  of the second blade, and a tangential line of the second concave side  43  of a first blade adjacent to the second blade, and the arc length L 2  of the second circular arc ranges from 0.35 times to 0.5 times of the arc length L 1  of the first circular arc. 
         [0031]    Referring to  FIGS. 7 and 8 , the lower plate  13  includes an upper side  131  and a lower side. The lower plate  13  is fixedly connected to the bottoms of the blades  12  via the upper side  131 , the upper side  131  of the lower plate  13  is configured to have a shape matching with the shape of the bottoms of the blades  12 , and the lower side of the lower plate  13  is substantially a horizontal plane. Blade mounting grooves  1311  are formed in the upper side  131  of the lower plate  13 , and the number of the blade mounting grooves  1311  is the same as the number of the first blades  121 . A stripe protrusion  133  is provided in each of the blade mounting grooves  1311 , and a small mounting hole  134  extending through the lower plate  13  is further provided in at least one of the blade mounting grooves  1311 , and the cylindrical protrusion  321  is provided on the bottom of a first blade corresponding to the at least one blade mounting groove  1311  provided with the small mounting hole  134  so as to fit the small mounting hole  134 . In this embodiment, each of the blade mounting grooves  1311  is provided with one small mounting hole  134 . During assembly of the impeller  1 , each of the cylindrical protrusions  321  of the bottoms  1211  of the first blades  121  is inserted into a respective small mounting hole  134 , and each of the bottoms  1211  of the first blades  121  is inserted into a respective blade mounting groove  1311 , and the first blades  121  are fixed to the lower plate  13  by ultrasonic welding, thus forming the impeller  1 . An impeller mounting hole  136  is formed in the lower plate  13 , and the impeller  1  is sleeved on an outer surface of the shaft  40  via the impeller mounting hole  136 . 
         [0032]    It should be noted that, the above embodiments are only intended for describing the present application, and should not be interpreted as a limitation to the technical solutions of the present application. Although the present application is described in detail in conjunction with the above embodiments, it should be understood by those skilled in the art that, modifications or equivalent substitutions may still be made to the present application by those skilled in the art; and any technical solutions and improvements of the present application without departing from the spirit and scope thereof also fall into the scope of the present application defined by the claims.