Electric water pump

Abstract

To generate pressure overcoming a back flow on an upstream side of an impeller, without increasing driving force for the impeller.SOLUTION: An electric water pump 1 is equipped with a housing 2 including a suction port 11 and a pump chamber 12 connecting to the suction port 11, and impellers 14 and 15 that are stored in the pump chamber 12, obtain rotation driving force to rotate about a support shaft 30, and include a plurality of main blades 14a and 15a flowing water sucked in an axial direction of the support shaft 30 outward in a diametrical direction. The plurality of main blades 14a and 15a are disposed on upstream sides toward the suction port sides of the impellers 14 and 15. Between the upstream sides of the impellers 14 and 15 and an inner wall 2Aa of the housing 2 opposed to the upstream sides, upstream side clearances 17 and 19 in which water can circulate are formed. A pressure loss generation structure generating pressure losses in the upstream side clearances 17 and 19 is provided.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to an electric water pump used in a cooling circuit or the like. [Background technology]

[0002] Conventionally, as an example of this type of technology, a "multi-blade fan" is known, as described in the following Patent Document 1. This fan includes a centrifugal multi-blade fan having a case having an air intake and a wall portion connected to the air intake, a plurality of main blades housed in the case and arranged in the circumferential direction, and a bottom plate formed at the ends of the main blades opposite the air suction side, and a plurality of sub-blades arranged in the circumferential direction at the air suction side ends of the main blades and formed so that air flows radially outward through gaps between the wall portion and the main blade portions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-332293 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the multi-blade blower described in Patent Document 1 is a technology for preventing the backflow of air to the air suction side end of the main blade, but in order to generate an air flow (pressure) that suppresses the backflow, it was necessary to increase the driving force of the drive device that drives the main blade. It is believed that this issue would be the same even if the handled fluid was changed from air to water and the centrifugal multi-blade fan was replaced with an impeller that causes water to flow radially outward.

[0005] This disclosed technology has been made in consideration of the above-mentioned circumstances, and its purpose is to provide an electric water pump that is capable of generating pressure that suppresses backflow upstream of the impeller without increasing the driving force for the impeller. [Means for solving the problem]

[0006] In order to achieve the above object, the technology described in claim 1 is an electric water pump comprising: a housing including a water intake and a pump chamber connected to the intake; an impeller housed in the pump chamber and rotating about a support shaft by obtaining a rotational driving force, the impeller including a plurality of main blades that cause water taken in in the axial direction of the support shaft to flow radially outward; and the plurality of main blades are arranged on the upstream side facing the impeller intake, wherein an upstream gap through which water can flow is formed between the upstream side of the impeller and the inner wall of the housing facing the upstream side, and a pressure loss generating structure that generates pressure loss in the upstream gap.

[0007] According to the configuration of the above technology, a pressure loss generating structure is provided in the upstream gap between the upstream side of the impeller and the inner wall of the housing facing that upstream side, and the pressure loss generated by the pressure loss generating structure increases the pressure in the upstream gap.

[0008] In order to achieve the above object, the technology described in claim 2 is the technology described in claim 1, wherein the upstream gap is formed so as to gradually narrow toward the radially outward direction of the impeller.

[0009] According to the configuration of the above technology, in addition to the effect of the technology described in claim 1, the upstream gap gradually narrows toward the radially outward direction of the impeller, so that the pressure of the water flowing in the radially outward direction of the impeller in the upstream gap increases efficiently.

[0010] In order to achieve the above object, the technology recited in claim 3 is directed to the technology recited in claim 1 or 2, wherein the pressure loss generating structure is a labyrinth structure formed by fitting, with play, an annular ridge provided on the upstream side of the impeller into an annular groove provided on the inner wall of the housing.

[0011] According to the configuration of the above technology, in addition to the effect of the technology described in claim 1 or 2, a pressure loss generating structure is formed by fitting the annular protrusion on the upstream side of the impeller into the annular groove on the inner wall of the housing.

[0012] In order to achieve the above object, the technology described in claim 4 is directed to the technology described in claim 1 or 2, in which a small pump is formed by accommodating a plurality of sub-vanes provided on the upstream side of the impeller in an annular groove provided on the inner wall of the housing so that the sub-vanes can rotate in the annular groove.

[0013] According to the configuration of the above technique, in addition to the effect of the technique described in claim 1 or 2, the small pump provided on the upstream side of the impeller operates in conjunction with the rotation of the impeller, thereby further increasing the pressure in the upstream gap. Also, the small pump is formed simply by accommodating multiple sub-vanes on the upstream side of the impeller in a rotatable manner in the annular groove on the inner wall of the housing.

[0014] In order to achieve the above object, the technology described in claim 5 is the technology described in claim 1 or 2, wherein the impeller has a plurality of sub-vanes on the radially outer side on the downstream side opposite to the upstream side, and an annular groove is provided on the opposing surface of the housing facing the downstream side of the impeller to accommodate the plurality of sub-vanes in a circumferential manner.

[0015] According to the configuration of the above technology, in addition to the function of the technology described in claim 1 or 2, a small pump is formed by simply accommodating a plurality of sub-vanes on the downstream side of the impeller in a rotatable manner in the annular groove on the opposing surface of the housing. Also, the small pump operates in conjunction with the rotation of the impeller, thereby suppressing the pressure rise on the downstream side of the impeller.

[0016] In order to achieve the above object, the technology described in claim 6 is the technology described in claim 5, in which the impeller has an axial hole at its center, is rotatably supported via a gap around a support shaft arranged to pass through the axial hole, is smoothly connected to the upstream side of the impeller, and is provided with an inlet adapter having a water inflow surface through which water flows in and a regulating surface that regulates the movement of the impeller in the thrust direction.

[0017] According to the configuration of the above technology, in addition to the effect of the technology described in claim 5, water smoothly flows into the upstream side of the impeller through the water inlet surface of the inlet adapter, and water can also flow through the regulating surface of the inlet adapter.

[0018] In order to achieve the above object, the technology recited in claim 7 is the technology recited in claim 1 or 2, in which an electric water pump is provided in a cooling system of an electric vehicle.

[0019] According to the configuration of the above technology, in addition to the effect of the technology described in claim 1 or 2, it is possible to reduce the driving force for an electric water pump used in a cooling system of an electric vehicle. Effect of the Invention

[0020] According to the technology described in claim 1, it is possible to generate pressure to suppress backflow in the gap upstream of the impeller without increasing the driving force for the impeller. Also, the impeller can be pressed downstream by the pressure increase generated in the gap upstream, and the force pressing the impeller upstream can be suppressed.

[0021] According to the technology described in claim 2, in addition to the effects of the technology described in claim 1, the force pushing the impeller upstream can be further suppressed, and the water supply that fills the water passage inside the housing with water can be further improved.

[0022] According to the technique recited in claim 3, in addition to the effect of the technique recited in claim 1 or 2, a pressure loss generating structure can be obtained with a simple configuration.

[0023] According to the technique recited in claim 4, in addition to the effect of the technique recited in claim 1 or 2, it is possible to further improve the water supply by filling the water passage inside the housing with water.

[0024] According to the technique recited in claim 5, in addition to the effect of the technique recited in claim 1 or 2, it is possible to suppress the force pressing the impeller toward the upstream side.

[0025] According to the technique recited in claim 6, in addition to the effect of the technique recited in claim 5, it is possible to suppress wear on the regulating surface of the inlet adaptor while regulating the movement of the impeller in the thrust direction.

[0026] According to the technology recited in claim 7, in addition to the effects of the technology recited in claim 1 or 2, the energy efficiency of electric vehicles can be improved, thereby contributing to energy conservation and carbon neutrality. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a front view showing an appearance of an electric water pump in a first embodiment. [Diagram 2] 1 is a cross-sectional view showing an electric water pump in a first embodiment. [Diagram 3] FIG. 2 is an exploded perspective view showing some of the components of the electric water pump in the first embodiment. [Figure 4] 3 is an enlarged cross-sectional view illustrating a portion surrounded by dashed double-dashed line rectangles S1 and S2 in FIG. 2 according to the first embodiment, the enlarged cross-sectional view illustrating a characteristic configuration provided corresponding to the first impeller and the second impeller. [Diagram 5] 3 is an enlarged cross-sectional view illustrating a portion surrounded by a dashed double-dashed line rectangle S3 in FIG. 2 according to the first embodiment, the enlarged cross-sectional view illustrating a characteristic configuration provided corresponding to a second impeller. [Figure 6] FIG. 2 is a circuit diagram showing an example of use of the electric water pump in the first embodiment. [Figure 7] 10 is an enlarged cross-sectional view illustrating a portion surrounded by dashed double-dashed line rectangles S1 and S2 in FIG. 2 according to a second embodiment, the enlarged cross-sectional view illustrating a characteristic configuration provided corresponding to the first impeller and the second impeller. [Figure 8] FIG. 11 is a plan view showing a part of an upper surface of a first cover of a first impeller in a second embodiment. [Figure 9] 10 is an enlarged cross-sectional view illustrating a portion surrounded by dashed double-dashed line rectangles S1 and S2 in FIG. 2 according to a third embodiment, the enlarged cross-sectional view illustrating a characteristic configuration provided corresponding to the first impeller and the second impeller. [Figure 10]10 is an enlarged cross-sectional view equivalent to FIG. 9 showing characteristic configurations provided corresponding to the first impeller and the second impeller in the portions surrounded by dashed double-dashed line rectangles S1 and S2 in FIG. 2 according to the fourth embodiment. [Figure 11] FIG. 13 is a cross-sectional view illustrating a schematic configuration of a support shaft and a rotor in a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, several embodiments in which an electric water pump is applied to a cooling system of an electric vehicle will be described.

[0029] First Embodiment The first embodiment will be described in detail with reference to FIGS.

[0030] [Basic configuration of electric water pump] Fig. 1 shows a front view of the appearance of electric water pump 1 of this embodiment. Fig. 2 shows a cross-sectional view of this electric water pump 1. Fig. 3 shows an exploded perspective view of some of the components of this electric water pump 1. Figs. 1 to 3 show the basic configuration of electric water pump 1, and the characteristic configuration of this embodiment will be illustrated and described later.

[0031] This electric water pump 1 is provided, for example, in a cooling system (described later) mounted on an electric vehicle and is used to circulate cooling water. As shown in Figures 1 to 3, electric water pump 1 has a cylindrical housing 2 made of resin, and is equipped with a pump section 3 and a motor section 4. Housing 2 includes an upper housing 2A, a middle housing 2B, and a lower housing 2C.

[0032] [About the pump] As shown in Figs. 1 to 3, the pump section 3 is provided in an upper housing 2A and a part of a middle housing 2B. An upwardly protruding water suction port 11 is provided at the top of the upper housing 2A. A pump chamber 12 is provided in the upper housing 2A and the middle housing 2B. The pump chamber 12 is divided into a first pump chamber 12A and a second pump chamber 12B by a resin water flow guide plate 13 that is disposed and fixed in the middle. A resin first impeller 14 is disposed in the first pump chamber 12A, and a resin second impeller 15 is disposed in the second pump chamber 12B. In this embodiment, each of the impellers 14, 15 is formed to rotate clockwise when viewed from the top of Fig. 2, i.e., from the side of the suction port 11 (hereinafter defined as the "upstream side").

[0033] As shown in Figs. 2 and 3, a plurality of main blades 14a are formed at regular intervals on the upstream side of the first impeller 14 in a curved vortex line shape. A resin first cover 16 is attached to the upstream side of the first impeller 14 so as to cover the main blades 14a. The first cover 16 is a component of the first impeller 14 and rotates integrally with the first impeller 14. An upstream gap 17 through which water can flow is provided between the first cover 16 located on the upstream side of the first impeller 14 and the inner wall 2Aa of the upper housing 2A facing it. A central hole 16a through which a support shaft 30 described later passes is formed in the center of the first cover 16.

[0034] As shown in Figs. 2 and 3, a plurality of main blades 15a are formed at regular intervals on the upstream side of the second impeller 15 in a curved vortex flow shape. A resin second cover 18 is attached to the upstream side of the second impeller 15 so as to cover these main blades 15a. The second cover 18 is a component of the second impeller 15 and rotates integrally with the second impeller 15. An upstream gap 19 through which water can flow is provided between the second cover 18 located on the upstream side of the second cover 18 and the lower surface 13a of the water flow guide plate 13 facing it. A central hole 18a through which a support shaft 30 described later passes is also formed in the center of the second cover 18.

[0035] 2 and 3, a plurality of blades 13b are formed at regular intervals in a vortex line shape on the upstream side of the water flow guide plate 13. The main blades 14a, 15a of each impeller 14, 15 and the blades 13b of the water flow guide plate 13 are curved in the same vortex direction. A center hole 13c is also formed in the center of the water flow guide plate 13, through which a support shaft 30 described later passes.

[0036] A series of pump section passages are formed in the upper housing 2A and the middle housing 2B. The pump section passages include an upstream gap 17 between the first cover 16 and the upper housing 2A, a center hole 16a of the first cover 16, a gap between the outer periphery of the first impeller 14 and the inner periphery of the upper housing 2A, a gap between the first impeller 14 and the water flow guide plate 13, a center hole 13c of the water flow guide plate 13, an upstream gap 19 between the second cover 18 and the lower surface 13a of the water flow guide plate 13, a center hole 18a of the second cover 18, a gap between the outer periphery of the second impeller 15 and the inner periphery of the middle housing 2B, and a gap between the lower surface of the second impeller 15 and the middle housing 2B. One end of the pump section passage is connected to the intake port 11, and the other end of the pump section passage is connected to a discharge port 20 (see Figs. 1 and 3) provided in the lower housing 2C via a motor section passage (described later) provided in the middle housing 2B and the lower housing 2C.

[0037] [About the motor] 2, the motor unit 4 is provided in the middle housing 2B and the lower housing 2C below the pump unit 3. The motor unit 4 is configured by a brushless motor. The motor unit 4 includes a support shaft 30, a rotor 31, and a stator 32.

[0038] The metallic support shaft 30 extends axially through the center of the upper housing 2A and the middle housing 2B, with its upper end fixed to a bearing 41 provided in the suction port 11 and its lower end fixed to a bearing 42 provided in the lower part of the middle housing 2B. A rotating body 33 integrally formed by the impellers 14, 15, the covers 16, 18, and the rotor 31 is rotatably supported by the support shaft 30. The rotating body 33 is disposed so as to cover most of the outer periphery of the support shaft 30, and a shaft gap 34 is formed between the inner periphery of the rotating body 33 and the outer periphery of the support shaft 30. This shaft gap 34 communicates with the pump section passage described above and the motor section passage described below.

[0039] The rotor 31 is cylindrical and accommodated in the intermediate housing 2B. The rotor 31 is disposed below the second impeller 15 with a gap therebetween, and is provided so as to be integral with the second impeller 15. The rotor 31 is disposed in series with the impellers 14, 15 in the axial direction. An upper end surface 31a of the rotor 31 is disposed facing the second impeller 15. The rotor 31 and the impellers 14, 15 are rotatable about the axis of the support shaft 30. The rotor 31 includes a cylindrical permanent magnet 43 provided on its outer periphery. The permanent magnet 43 has a plurality of magnetic poles in the circumferential direction.

[0040] The inner housing 2B has an inner circumferential surface 2Ba and a bottom surface 2Bb. The inner circumferential surface 2Ba faces the outer periphery of the rotor 31 and surrounds the periphery of the rotor 31. The bottom surface 2Bb faces the lower end surface 31b of the rotor 31. A rotor gap 35 is formed between the inner circumferential surface 2Ba of the inner housing 2B and the outer periphery of the rotor 31. Meanwhile, a bottom gap 36 is formed between the bottom surface 2Bb of the inner housing 2B and the lower end surface 31b of the rotor 31. The motor passage includes the rotor gap 35 and the bottom gap 36 described above.

[0041] The stator 32 is accommodated in the intermediate housing 2B on the outer circumferential side of the rotor 31. The stator 32 includes a metal core 51. The core 51 is formed by stacking a plurality of core plates. A coil wire 52 is wound around the core 51.

[0042] A control circuit 55 is provided in the lower housing 2C to control the power supply to the stator 32. The control circuit 55 is connected to an external power source via a terminal (not shown). The control circuit 55 supplies the motor unit 4 with power supplied from the external power source.

[0043] [Characteristic configuration of this embodiment] In the basic configuration of the electric water pump 1 described above, when a backflow occurs in the upstream gaps 17, 19 of each impeller 14, 15, a pressure difference occurs between the upstream and downstream sides of each impeller 14, 15, generating a thrust force that pushes each impeller 14, 15 upstream. In response to this, it is conceivable to provide an SE ring or a washer between each impeller 14, 15 and the support shaft 30 in order to regulate the upward thrust of each impeller 14, 15. However, such a measure raises concerns that sliding resistance and wear may increase in each impeller 14, 15. Therefore, in this embodiment, the above problem is addressed by the following characteristic configuration.

[0044] FIG. 4 is a schematic enlarged cross-sectional view showing a characteristic configuration provided in correspondence with the first impeller 14 and the second impeller 15 in the portion surrounded by the two-dot chain line rectangles S1 and S2 in FIG. 2 according to this embodiment. As shown in FIG. 4, in this embodiment, a pressure loss generating structure 10 that generates pressure loss is provided in the upstream gap 17 between the inner wall 2Aa of the upper housing 2A and the upper surface 16b of the first cover 16. This pressure loss generating structure 10 is a labyrinth structure 63 formed by fitting an annular protrusion 62 provided on the upper surface 16b of the first cover 16 into an annular groove 61 provided on the inner wall 2Aa of the upper housing 2A with some play. The annular groove 61 is formed in an annular shape on the inner wall 2Aa of the upper housing 2A. The annular protrusion 62 is formed in an annular shape on the upper surface 16b of the first cover 16. This pressure loss generating structure 10 is preferably provided at a radially outer position. By providing the pressure loss generating structure 10 at a radially outer position, the force pushing up the impellers 14, 15 in the vertical direction can be suppressed.

[0045] The labyrinth structure 63 may be provided in only one of the areas surrounded by the dashed double-dashed line rectangles S1 and S2 in FIG.

[0046] 5 is a schematic enlarged cross-sectional view of a characteristic configuration provided for the second impeller 15 in the portion surrounded by a two-dot chain line rectangle S3 in FIG. 2 according to this embodiment. As shown in FIG. 5, in this embodiment, the second impeller 15 has a plurality of sub-vanes 65 arranged in a circular ring shape around the central axis of the second impeller 15 on the radially outer side of the lower surface 15c opposite to the upper surface 15b (also opposite to the upper surface of the second cover 18). A circular annular groove 66 that accommodates the plurality of sub-vanes 65 so as to be able to rotate is provided on the opposing surface 2Bc of the intermediate housing 2B that faces the lower surface 15c on the downstream side of the second impeller 15. The plurality of sub-vanes 65 are fitted into the annular groove 66 with some play, and are arranged so as to be able to rotate in the annular groove 66 to form a small pump 67. This small pump 67 is provided in correspondence with the downstream gap 21 of the second impeller 15 formed between the lower surface 15c of the second impeller 15 and the opposing surface 2Bc of the middle housing 2B. This small pump 67 is a pump that discharges in the radially outward direction, and is desirably provided in the radially outward direction. By providing the small pump 67 in the radially outward direction, the force pushing the impellers 14, 15 upward can be suppressed. In addition, in the case of a one-stage pump (impeller), the small pump 67 may be provided on the lower surface of the first impeller 14.

[0047] FIG. 6 shows a circuit diagram of an example of use of the electric water pump 1 described above. As shown in FIG. 6, in this embodiment, the electric water pump 1 is used as a first electric water pump 97 and a second electric water pump 98 in a cooling system 91 mounted on an electric vehicle 90. The cooling system 91 corresponds to an example of a "cooling system" of this disclosed technology. In addition to the two electric water pumps 97 and 98, the cooling system 91 includes a radiator 92, a PCU 93, a battery 94, and a chiller 95. A first pipe 96A is connected to the radiator 92, a second pipe 96B is connected to the CPU 93, a third pipe 96C is connected to the battery 94, and a fourth pipe 96D is connected to the chiller 95. In addition to the PCU 93, the first electric water pump 97 is provided in the second pipe 96B, and in addition to the chiller 95, the second electric water pump 98 is provided in the fourth pipe 96D. Both ends of the first pipe 96A are connected to the sixth inflow / outflow passage 99F and the second inflow / outflow passage 99B of the flow path switching device 100, and both ends of the second pipe 96B are connected to the seventh inflow / outflow passage 99G and the third inflow / outflow passage 99C of the flow path switching device 100. Both ends of the third pipe 96C are connected to the fourth inflow / outflow passage 99D and the eighth inflow / outflow passage 99H of the flow path switching device 100, and both ends of the fourth pipe 96D are connected to the first inflow / outflow passage 99A and the fifth inflow / outflow passage 99E of the flow path switching device 100. The flow path switching device 100 is driven while operating the electric water pumps 97 and 98, and the flow paths are switched to control the flow of the cooling water to each of the parts 92 to 95.

[0048] [About the function and effect of electric water pumps] According to the configuration of the electric water pump 1 of this embodiment described above, the pressure loss generating structure 10 is provided in the upstream gap 17 between the upstream side of the first impeller 14 (the upper surface 16b of the first cover 16) and the inner wall 2Aa of the upper housing 2A facing the upper surface 16b, and the pressure in the upstream gap 17 is increased by generating a pressure loss by the pressure loss generating structure 10. Therefore, it is possible to generate a pressure that suppresses a backflow in the upstream gap 17 of the first impeller 14 without increasing the driving force for the first impeller 14. In addition, the first impeller 14 can be pressed downstream by the pressure increase generated in the upstream gap 17 (the backflow amount is suppressed by the pressure loss generating structure 10, and the pressure increases), and the force pressing the first impeller 14 upstream can be suppressed. The second impeller 15 can also obtain the same action and effect as described above.

[0049] According to the configuration of this embodiment, the pressure loss generating structure 10 consisting of a labyrinth structure 63 is formed by fitting the annular protrusion 62 on the upstream side of the first impeller 14 (upper surface 16b of the first cover 16) into the annular groove 61 on the inner wall 2Aa of the upper housing 2A. Therefore, the pressure loss generating structure 10 can be obtained with a simple configuration. The same actions and effects as those described above can be obtained for the second impeller 15.

[0050] According to the configuration of this embodiment, a small pump 67 is formed by simply accommodating multiple sub-vanes 65 on the downstream side (lower surface 15c) of the second impeller 15 in a rotatable manner in the annular groove 66 on the opposing surface 2Bc of the middle housing 2B. In addition, the small pump 67 operates in conjunction with the rotation of the second impeller 15, thereby suppressing a pressure increase on the lower surface 15c of the second impeller 15. Therefore, by providing the small pump 67 in the radially outer direction, it is possible to suppress the force pressing the second impeller 15 toward the upstream side.

[0051] According to the configuration of this embodiment, it is possible to reduce the driving force of the motor unit 3 of the electric water pumps 97, 98 used in the cooling system 91 of the electric vehicle 90. As a result, it is possible to improve the energy efficiency of the electric vehicle 90, thereby contributing to energy saving and carbon neutrality.

[0052] <Second embodiment> The second embodiment will be described in detail with reference to Figures 7 and 8. In the following description, the same components as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted, and differences will be mainly described.

[0053] [Characteristic configuration of this embodiment] This embodiment differs from the first embodiment in terms of its characteristic configuration. Fig. 7 shows a schematic enlarged cross-sectional view of the characteristic configuration provided for the first impeller 14 and the second impeller 15 in the portion surrounded by the two-dot chain line rectangles S1 and S2 in Fig. 2 according to this embodiment. Fig. 8 shows a plan view of a part of the upper surface 16b of the first cover 16 of the first impeller 14.

[0054] 7, this embodiment includes an annular groove 61 provided in the inner wall 2Aa of the upper housing 2A, and a plurality of sub-vanes 69 arranged in a circular ring shape around the central hole 16a on the upper surface 16b of the first cover 16. The sub-vanes 69 are fitted into the annular groove 61 with some play, and are arranged rotatably within the annular groove 61 to form a miniature pump 70.

[0055] As shown in FIG. 8, the sub-vanes 69 are arranged with a predetermined number of vanes, and have a predetermined inclination angle θ1 and a predetermined vane length L1 with respect to the radial direction of the first cover 16. It is preferable that at least one of the elements of the number of vanes, the inclination angle θ1, and the vane length L1 is increased as the pressure difference between the top and bottom of the first cover 16 increases. Each sub-vane 69 may be linear or curved in plan view. This small pump 70 is a pump that discharges in the radially outward direction, and is preferably provided at a radially inner position. By providing the small pump 70 at a radially inner position, the pressure in the upstream gap 17 on the upstream side of the first impeller 14 increases, and the force pushing each impeller 14, 15 upward can be suppressed.

[0056] The above-mentioned miniature pump 67 may be provided in only one of the areas surrounded by the two-dot chain line rectangles S1 and S2 in FIG.

[0057] [About the function and effect of electric water pumps] According to the configuration of the electric water pump 1 of this embodiment described above, the small pump 70 provided on the upstream side (first cover 16) of the first impeller 14 operates with the rotation of the first impeller 14, thereby further increasing the pressure in the upstream gap 17. Moreover, the small pump 70 is formed simply by accommodating the multiple sub-vanes 69 of the first cover 16 of the first impeller 14 in a rotatable manner in the annular groove 61 of the inner wall 2Aa of the upper housing 2A. This further improves the water supply that fills the water passage inside the upper housing 2A with water. The second impeller 15 can also achieve the same actions and effects as those described above.

[0058] <Third embodiment> The third embodiment will be described in detail with reference to FIG.

[0059] [Characteristic configuration of this embodiment] This embodiment differs from the above-mentioned embodiments in terms of its characteristic configuration. Fig. 9 is a schematic enlarged cross-sectional view of the characteristic configuration provided in this embodiment corresponding to the first impeller 14 and the second impeller 15 in the area surrounded by the two-dot chain line rectangles S1 and S2 in Fig. 2. As shown in Fig. 9, in this embodiment, the pressure loss generating structure 10 consisting of the labyrinth structure 63 described above is provided near the radially outer periphery of the first cover 16, and a miniature pump 68 equivalent to the miniature pump 70 described above is provided around the periphery of the central hole 16a of the first cover 16.

[0060] In this embodiment, a labyrinth structure 63 is provided between the inner wall 2Aa of the upper housing 2A and the upper surface 16b of the first cover 16, radially outward from the main blade 14a of the first impeller 14. Also, a mini-pump 68 is provided between the inner wall 2Aa of the upper housing 2A and the upper surface 16b of the first cover 16, radially inward from the main blade 14a of the first impeller 14. In this embodiment, an upstream gap 17 is formed with a constant clearance between the labyrinth structure 63 and the mini-pump 68.

[0061] A labyrinth structure 63 and a small pump 68 similar to those described above can be provided in the area surrounded by a two-dot chain line rectangle S2 in FIG.

[0062] [About the function and effect of electric water pumps] According to the configuration of the electric water pump 1 of this embodiment described above, for the first impeller 14, the small pump 68 is formed on the radially inner side of the first cover 16, and the labyrinth structure 63 is formed near the radially outer periphery, so that the discharge pressure from the small pump 68 generates a pressure loss in the labyrinth structure 63, increasing the pressure in the upstream gap 17. Therefore, a pressure that overcomes the backflow can be generated in the upstream gap 17 of the first impeller 14. In addition, the pressure generated in the upstream gap 17 can press the first impeller 14 downstream, and the force pressing the first impeller 14 upstream can be suppressed.

[0063] According to the configuration of this embodiment, a small pump 68 is formed around the periphery of the central hole 16a of the first cover 16 for the first impeller 14, so that the pressure generated in the upstream gap 17 can be increased by the small pump 68. Therefore, the downstream side of the first impeller 14 can be pushed down by the amount of the increase in pressure in the upstream gap 17, and the sliding force pushing the first impeller 14 up toward the upstream side can be suppressed. In addition, the clearance of the upstream gap 17 can be expanded by the amount of the increase in pressure in the upstream gap 17, and the water supply that fills the water passage inside the upper housing 2A with water can be improved.

[0064] Moreover, according to the configuration of this embodiment, the second impeller 15 can also achieve the same effects and advantages as those described above.

[0065] <Fourth embodiment> The fourth embodiment will be described in detail with reference to FIG.

[0066] [Characteristic configuration of this embodiment] This embodiment differs from the third embodiment in terms of its characteristic configuration. Fig. 10 shows, in an enlarged cross-sectional view equivalent to Fig. 9, the characteristic configuration provided in correspondence with the first impeller 14 and the second impeller 15 in the portion surrounded by the two-dot chain line rectangles S1 and S2 in Fig. 2. As shown in Fig. 10, this embodiment differs from the third embodiment in terms of the configurations of the mini-pump 68 and the upstream gap 17.

[0067] That is, in the mini-pump 68 of this embodiment, the blade length L1 of the sub-blade 69 is longer than that of the third embodiment, and the width of the annular groove 61 is correspondingly larger. Also, as shown in Fig. 10, the upstream gap 17 between the mini-pump 68 and the labyrinth structure 63 is formed so as to gradually narrow in the radially outward direction of the first impeller 14, i.e., in the radially outward direction of the first cover 16.

[0068] A configuration similar to the above may be provided in the portion surrounded by a two-dot chain line rectangle S2 in FIG.

[0069] [About the function and effect of electric water pumps] According to the configuration of the electric water pump 1 of this embodiment described above, in addition to the actions and effects of the third embodiment, the following actions and effects can be obtained. That is, for the first impeller 14, the upstream gap 17 gradually narrows toward the radially outward direction of the first impeller 14, so that the pressure of the water flowing in the radially outward direction of the first impeller 14 in the upstream gap 17 efficiently increases. This makes it possible to further suppress the force pushing the first impeller 14 upward (upstream). In addition, because the upstream gap 17 is enlarged, it is possible to further improve the water supply that fills the water passage inside the upper housing 2A with water. For the second impeller 15, the same actions and effects as those described above can be obtained.

[0070] According to the configuration of this embodiment, the small pump 68 is provided on the periphery of the central hole 16a of the first cover 16 for the first impeller 14, so water is supplied to the small pump 68 without any problems. Therefore, the upstream gap 17 is enlarged by providing the small pump 68, so that when the pump section 3 is stopped, the entire water passage inside the housing 2 can be filled with water. In other words, a "forced water supply function" can be obtained. The same actions and effects as those described above can be obtained for the second impeller 15.

[0071] Furthermore, according to the configuration of this embodiment, when a sliding force acts on the rotor 33 toward its upstream side, the clearances of the upstream gaps 17, 19 of the impellers 14, 15 are reduced, and the pump efficiency (discharge pressure) of the miniature pump 68 increases. Then, the sliding force on the rotor 33 toward the downstream side increases, pushing the rotor 33 down toward the downstream side. As a result, the upstream gaps 17, 19 of the impellers 14, 15 can be automatically adjusted to an optimal clearance. That is, it is possible to obtain an "optimal adjustment function for the upstream gap" while suppressing the amount of water leakage (backflow amount) toward the inlet side of the pump section 3 (after increasing the pump efficiency).

[0072] <Fifth embodiment> The fifth embodiment will be described in detail with reference to FIG.

[0073] [Characteristic configuration of this embodiment] This embodiment differs from the first embodiment in terms of a characteristic configuration. In addition to the configuration of the first embodiment, this embodiment includes the following configuration. FIG. 11 shows a schematic cross-sectional view of the configuration of the support shaft 30 and the rotor 33 according to this embodiment. As shown in FIG. 11, the rotor 33 includes the first impeller 14 and the second impeller 15. The first impeller 14 has an axial hole 14b at its center, and is supported rotatably through the axial gap 34 around the support shaft 30 disposed to penetrate the axial hole 14b. Similarly, the second impeller 15 has an axial hole 15d at its center, and is supported rotatably through the axial gap 34 around the support shaft 30 disposed to penetrate the axial hole 15d. Here, the inlet adapter 6 is provided on the upper surface 14c of the first impeller 14, and has a water inflow surface 6a through which water flows in and a restriction surface 6b that restricts the movement of the first impeller 14 in the thrust direction. Furthermore, on the support shaft 30, between the upper surface 14c of the first impeller 14 and the regulating surface 6b of the inlet adapter 6, an SE ring 7 and a washer 8 are provided.

[0074] In this embodiment, the upstream side of the shaft gap 34 shown in FIG. 11 (the lower side of FIG. 11) is connected to the downstream gap 21 described in the first embodiment. As a result, by the action of the small pump 67 provided in the downstream gap 21, as shown by the dashed arrow in FIG. 11, the water flowing upward through the shaft gap 34 flows to the first impeller 14 through the gap between the upper surface 14c of the first impeller 14 and the water inlet surface 6a of the inlet adapter 6. This water pressure acts on the support shaft 30 through the washer 8 and the SE ring 7, fixing the support shaft 30 to the bearing 41 and suppressing the movement of the support shaft 30 in the thrust direction. Here, the thrust force acting on the support shaft 30 is received by the washer 8, so it is desirable to guide the water to between the washer 8 and the first impeller 14 without leaking on the way. For this reason, in order to minimize the clearance between the first impeller 14 and the second impeller 15, it is necessary to bring the first impeller 14 and the second impeller 15 into close contact with each other as much as possible.

[0075] [About the function and effect of electric water pumps] The configuration of the electric water pump 1 of this embodiment described above provides the following actions and effects in addition to those of the first embodiment. That is, water smoothly flows into the upstream side of the first impeller 14 via the water inlet surface 6a of the inlet adapter 6, and water can also flow through the regulating surface 6b of the inlet adapter 6. Therefore, wear on the regulating surface 6b of the inlet adapter 6 can be suppressed while regulating the movement of the first impeller 14 in the thrust direction.

[0076] <Another embodiment> The disclosed technology is not limited to the above-described embodiments, and may be implemented by modifying part of the configuration as appropriate without departing from the spirit of the disclosed technology.

[0077] (1) In each of the above embodiments, the rotor 33 is configured as a two-stage impeller having a first impeller 14 and a second impeller 15. However, it may also be configured as a single-stage impeller rotor having a single impeller. [Industrial Applicability]

[0078] The disclosed technology can be used, for example, in an electric water pump used in the cooling system of an electric vehicle. [Explanation of symbols]

[0079] 1 Electric water pump 2. Housing 2Aa Inner wall 2Bc Opposite side 6 Inlet Adapter 6a Water inflow surface 6b Regulatory aspects 10 Pressure loss generation structure 11 Intake port 12 Pump Room 13 Water flow guide plate (housing) 14 First impeller 14a Main feather 14b Shaft hole 15 Second impeller 15a Main feather 15d shaft hole 16 First cover (first impeller) 16b Top surface (upstream side) 17 Upstream gap 18 Second cover (second impeller) 19 Upstream gap 30 Spindle 34 Shaft clearance 61 Annular groove (upstream side) 62 Annular ridge 63 Maze structure 65 Sub-blade (downstream) 66 Annular groove (downstream) 67 Small Pump 68 Small Pump 69 Sub-wing (upstream) 70 Small Pump 90 Electric vehicle 91 Cooling system 97 No. 1 electric water pump 98 No. 2 electric water pump

Claims

1. a housing including a water inlet and a pump chamber communicating with the water inlet; an impeller that is housed in the pump chamber, rotates around a support shaft by receiving a rotational driving force, and includes a plurality of main blades that cause water drawn in in the axial direction of the support shaft to flow radially outward; The plurality of main blades are disposed on an upstream side of the impeller facing the suction port. In an electric water pump comprising: an upstream gap through which water can flow is formed between the upstream side of the impeller and an inner wall of the housing facing the upstream side; A pressure loss generating structure that generates a pressure loss in the upstream gap An electric water pump.

2. 2. The electric water pump according to claim 1, The upstream gap is formed so as to gradually narrow toward the radially outer direction of the impeller. An electric water pump.

3. 3. The electric water pump according to claim 1, The pressure loss generating structure is a labyrinth structure formed by fitting an annular protrusion provided on the upstream side of the impeller into an annular groove provided on the inner wall of the housing with some play. An electric water pump.

4. 3. The electric water pump according to claim 1, A miniature pump is formed by circumferentially accommodating a plurality of sub-vanes provided on the upstream side of the impeller in an annular groove provided on the inner wall of the housing. An electric water pump.

5. 3. The electric water pump according to claim 1, The impeller has a plurality of sub-vanes on a radially outer side on a downstream side opposite to the upstream side, An annular groove is provided on a surface of the housing facing the downstream side of the impeller to accommodate the sub-vanes so as to be able to circumferentially move therethrough. An electric water pump.

6. 6. The electric water pump according to claim 5, The impeller has a shaft hole at its center, and is supported rotatably around the support shaft disposed to pass through the shaft hole via a gap, The inlet adapter is smoothly connected to the upstream side of the impeller and has a water inflow surface through which water flows and a restriction surface that restricts the movement of the impeller in the thrust direction. An electric water pump.

7. 3. The electric water pump according to claim 1, The electric water pump is provided in a cooling system of an electric vehicle. An electric water pump.

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