Multi-stage electric water pump

Abstract

To provide a multi-stage electric water pump having an impeller and a water flow guiding panel for guiding the water flow that rotationally flows out of a centrifugal side of the impeller from the centrifugal side to a center side, the pump improving a compression efficiency of the water flow that flows from the water flow guiding panel to the next-stage impeller to improve a pump efficiency.SOLUTION: An impeller is stored in each of two pump chambers, the impeller rotationally flowing the water sucked from a center side thereof to a centrifugal side. A water flow guiding panel 13 is fixed between the two pump chambers, the guiding panel guiding the water flow rotationally flown out from a centrifugal side of the upstream impeller to a center side from the centrifugal side. The water flow guiding panel 13 includes a plurality of guiding blades 13b about a water flow-out hole 13c formed at the center thereof, the guiding blades being provided in a spirally-curved manner in the same spiral direction as the impeller blade at a predefined interval. The guiding blade 13b includes a reverse part 6 that reverses a water flow rotation direction toward a center side from the centrifugal side of the water flow guiding panel 13.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] Conventionally, as this type of technology, for example, a "multi-stage pump" described in Patent Document 1 below is known. This multi-stage pump is configured by arranging a plurality of pump stages, each of which is a pair of an impeller and a guide vane portion (water flow guide plate) in a casing portion (housing) along the axial direction of a main shaft. The impeller is provided integrally with the main shaft and is adapted to suck in fluid from the center side by rotation and discharge (rotation out) to the centrifugal side. The water flow guide plate is adapted to straighten (guide) the flow of fluid from the centrifugal side to the center side. The housing accommodates the main shaft and the impeller rotatably therein, and has the water flow guide plate fixed therein. The impeller and the water flow guide plate are arranged in this order in the housing along the axial direction of the main shaft and the direction of fluid flow. The impeller has a first through hole at its center through which the main shaft is inserted, a plurality of impeller blades are arranged, and a disk-shaped impeller side wall part is provided in contact with the side surfaces of the plurality of impeller blades and centered on the main shaft inserted in the first through hole. The water flow guide plate has a second through hole at its center through which the main shaft is inserted, a plurality of guide blades are arranged, and a disk-shaped guide blade side wall part is provided in contact with the side surfaces of the plurality of guide blades and centered on the main shaft inserted in the second through hole. Only a swirling space configured as a fluid flow path exists between the impeller and the water flow guide plate, and the swirling space is a space formed on the outside of the centrifugal side of the impeller side wall part and on the outside of the centrifugal side of the water flow guide plate, respectively.

[0003] In this multi-stage pump, fluid is sucked in from the center side of the impeller in the upstream pump stage, discharged from the centrifugal side, flows from the centrifugal side of the water flow guide plate to the center side, is rectified and pressurized. The pressurized fluid is then sucked in from the center side of the impeller in the next downstream pump stage, is discharged from the centrifugal side, flows from the centrifugal side of the water flow guide plate to the center side, is rectified and pressurized. The pressurized fluid then flows to the next pump stage and is pressurized. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-91317 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the multi-stage pump described in Patent Document 1, the impeller vanes of the impeller and the guide vanes of the water flow guide plate are arranged at regular intervals in a curved vortex line shape and are curved in the same vortex direction. Therefore, in each pump stage, the flow of the fluid discharged from the centrifugal side of the impeller and flowing from the centrifugal side to the center of the water flow guide plate rotates in the opposite direction to the flow of the fluid flowing from the center to the centrifugal side of the impeller in the downstream pump stage. Therefore, in the downstream pump stage, the compression efficiency of the fluid decreases, and there is a risk of the pump efficiency deteriorating.

[0006] This disclosed technology has been made in consideration of the above-mentioned circumstances, and its purpose is to improve the compression efficiency of the water flow flowing from the water flow guide plate into the next stage impeller, and improve pump efficiency, in a multi-stage electric water pump equipped with an impeller and a water flow guide plate that guides the water flow rotating and flowing out from the centrifugal side of the impeller from the centrifugal side to the center side. [Means for solving the problem]

[0007] In order to achieve the above object, the technology described in claim 1 is provided with a cylindrical housing including a plurality of pump chambers arranged in the axial direction, and each of the plurality of pump chambers accommodates an impeller that rotates about a support shaft by obtaining a rotational driving force and rotates water drawn in from the center side to the centrifugal side, and a water flow guide plate is fixed between adjacent pump chambers to guide the water flow rotating and flowing out from the centrifugal side of the upstream impeller from the centrifugal side to the center side, and the water flow rotating and flowing out from the centrifugal side of the impeller is guided from the centrifugal side of the water flow guide plate to the center side. In a multi-stage electric water pump in which the water is pressurized by rotating the impeller, a water inlet hole is formed at the center of the impeller through which water flows in, and a plurality of impeller vanes are arranged in a curved vortex line at predetermined intervals around the water inlet hole, and a water flow guide plate is formed at the center of the water outlet hole through which water flows out, and a plurality of guide vanes are arranged in a curved vortex line at predetermined intervals around the water outlet hole, in the same vortex direction as the impeller vanes, and the guide vanes have a reversing portion that reverses the rotational direction of the water flow from the centrifugal side to the center of the water flow guide plate.

[0008] According to the configuration of the above technology, the water flow that rotates while flowing out from the centrifugal side of the impeller in the pump chamber of the previous stage and rotates while flowing in from the centrifugal side of the water flow guide plate flows out from the water outlet hole on the central side while rotating. Here, the water flow that is about to flow out of the water outlet hole reverses its rotation direction from the centrifugal side to the water outlet hole at the reversing part of the guide vane. Therefore, the rotation direction of the water flow that flows from the water outlet hole of the water flow guide plate into the water inlet hole of the impeller of the next pump chamber coincides with the rotation direction of the water flow that flows from the water inlet hole of the impeller to the centrifugal side.

[0009] In order to achieve the above object, the technology described in claim 2 is the technology described in claim 1, wherein the guide vane is convexly curved to follow the rotation trajectory of the impeller, and the inverted portion is formed by increasing the curvature of the downstream end portion which is the end portion of the guide vane in the curved direction and close to the center, and an imaginary extension line of the downstream end portion circumscribes the outer edge of the water outflow hole or passes near the circumscribed position.

[0010] According to the configuration of the above technique, in addition to the effect of the technique described in claim 1, a reversing portion can be obtained simply by increasing the curvature of the downstream end portion close to the center, which is the end portion in the curved direction of the guide vane.

[0011] In order to achieve the above object, the technology recited in claim 3 is the technology recited in claim 1 or 2, in which a multi-stage electric water pump is provided in a cooling system of an electric vehicle.

[0012] According to the configuration of the above technology, in addition to the effect of the technology described in claim 1 or 2, the driving force of a multi-stage electric water pump used in a cooling system of an electric vehicle is reduced. Effect of the Invention

[0013] According to the technology described in claim 1, in a multi-stage electric water pump equipped with an impeller and a water flow guide plate that guides the water flow rotating and flowing out from the centrifugal side of the impeller from the centrifugal side to the center side, the compression efficiency of the water flow flowing from the water flow guide plate to the next stage impeller can be improved, and the pump efficiency can be improved.

[0014] According to the technique recited in claim 2, in addition to the effect of the technique recited in claim 1, the reversal portion can be easily implemented without adding a separate member.

[0015] According to the technology recited in claim 3, 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]

[0016] [Figure 1] 1 is a front view showing an appearance of an electric water pump in one embodiment; [Diagram 2] 1 is a cross-sectional view showing an electric water pump in one embodiment; [Diagram 3] FIG. 2 is an exploded perspective view showing some of the components of the electric water pump in the embodiment; [Figure 4]FIG. 4 is a plan view showing the upstream side (top side) of each impeller in one embodiment. [Diagram 5] FIG. 4 is a plan view showing the upstream side (upper surface side) of the water flow guide plate in one embodiment. [Figure 6] 1 is a circuit diagram showing an example of use of an electric water pump in one embodiment; [Figure 7] FIG. 4 is a plan view showing a water flow in a water flow guide plate according to one embodiment. [Figure 8] FIG. 11 is a plan view showing a water flow guide plate having no reversing portion as a comparative example. [Figure 9] FIG. 11 is a plan view showing a water flow in a water flow guide plate in a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description will be given of an embodiment of a multi-stage electric water pump with reference to the drawings.

[0018] [Basic configuration of a multi-stage electric water pump] Fig. 1 shows a front view of the appearance of electric water pump 1 according to this embodiment. Fig. 2 shows a cross-sectional view of electric water pump 1 according to this embodiment. Fig. 3 shows an exploded perspective view of some of the components of electric water pump 1 according to this embodiment. 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.

[0019] 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 Figs. 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. A support shaft 30 is fixed to the center of housing 2, extending in the axial direction thereof.

[0020] [About the pump] As shown in Figs. 1 to 3, the pump section 3 is provided in the upper housing 2A and a part of the middle housing 2B. A water intake port 11 that protrudes upward 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 fixed to the middle. That is, the housing 2 includes the first pump chamber 12A and the second pump chamber 12B arranged in the axial direction. The first pump chamber 12A accommodates a first impeller 14 made of resin that rotates around the support shaft 30 by receiving a rotational driving force and rotates the water sucked from the center side to the centrifugal side. The second pump chamber 12B accommodates a second impeller 15 made of resin that rotates around the support shaft 30 by receiving a rotational driving force and rotates the water sucked from the center side to the centrifugal side. In this embodiment, each of the impellers 14, 15 rotates clockwise as viewed from above in FIG. 2, that is, from the side of the suction port 11 (hereinafter defined as the "upstream side").

[0021] FIG. 4 shows the upstream side (upper surface side) of the first impeller 14 and the second impeller 15 in this embodiment in a plan view. As shown in FIGS. 2 to 4, the first impeller 14 has a water inlet hole 16a through which the support shaft 30 penetrates at its center and through which water flows in. On the upstream side of the impeller 14, a plurality of impeller blades 14a are provided in a curved vortex shape at a predetermined interval (in this case, a constant interval) centered on the water inlet hole 16a. On the upstream side of the first impeller 14, a first cover 16 made of resin is attached so as to cover the impeller blades 14a. The first cover 16 is a component that constitutes the first impeller 14 and rotates integrally with the first impeller 14. The water inlet hole 16a is formed at the center of the first cover 16. Between the first cover 16 and the inner wall 2Aa of the upper housing 2A facing it, an upstream gap 17 through which water can flow is provided.

[0022] As shown in Figs. 2 to 4, the second impeller 15 has a water inlet 18a through which the shaft 30 passes and through which water flows in. On the upstream side of the impeller 15, a plurality of impeller blades 15a are arranged in a curved vortex shape at regular intervals centered on the water inlet 18a. On the upstream side of the second impeller 15, a resin second cover 18 is attached so as to cover the impeller blades 15a. The second cover 18 is a component that constitutes the second impeller 15 and rotates integrally with the second impeller 15. The water inlet 18a is formed in the center of the second cover 18. Between the second cover 18 and the lower surface 13a of the water flow guide plate 13 facing it, an upstream gap 19 is provided through which water can flow.

[0023] As shown in Figures 2 and 3, the water flow guide plate 13 is configured to guide the flow of water rotating and flowing out from the centrifugal side of the first impeller 14 on the upstream side from the centrifugal side to the center side. The water flow guide plate 13 has a support shaft 30 penetrating through its center, a water outflow hole 13c through which the water flows out, and a plurality of guide vanes 13b are provided at regular intervals in the form of curved vortex lines centered on the water outflow hole 13c. Each of the impeller vanes 14a, 15a and the guide vanes 13b are curved in the same vortex direction.

[0024] In this electric water pump 1, water rotating out from the centrifugal side of the first impeller 14 is guided from the centrifugal side of the water flow guide plate 13 to the water outlet hole 13c on the central side, where it is pressurized, and is then sucked into the water inlet hole 18a on the central side of the second impeller 15, rotates from the water inlet hole 18a to the centrifugal side, and rotates out from the centrifugal side.

[0025] 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 water inlet 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 water outlet 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 water inlet 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, a gap between the lower surface of the second impeller 15 and the middle housing 2B, and the like. 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.

[0026] [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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] [Characteristic configuration of this embodiment] In the basic configuration of the electric water pump 1 described above, the rotation direction of the water flow that rotates out from the centrifugal side of the first impeller 14 and flows in from the centrifugal side of the water flow guide plate 13 is the same as the clockwise rotation direction of each impeller 14, 15. Therefore, if the water flows out of the water outlet hole 13c on the center side of the water flow guide plate 13 as it is, the rotation direction will be opposite to the rotation direction of the water flow that flows from the water inlet hole 18a on the center side of the second impeller 15 to the centrifugal side (the direction shown by the dashed arrow in FIG. 4). Therefore, the water compression efficiency of the second impeller 15 decreases, and there is a risk that the pump efficiency of the electric water pump 1 will deteriorate. Therefore, in this embodiment, the above problem is addressed by the following characteristic configuration.

[0033] FIG. 5 shows a plan view of the upstream side (upper surface side) of the water flow guide plate 13 according to this embodiment. As shown in FIG. 5, in the water flow guide plate 13 according to this embodiment, the guide vane 13b has a reversing portion 6 (a portion surrounded by a dashed line ellipse) that reverses the rotation direction of the water flow from the centrifugal side of the water flow guide plate 13 to the water outflow hole 13c on the central side. Here, the guide vane 13b is formed so as to be convex toward the centrifugal side along the rotation trajectory of each impeller 14, 15 and curved so as to converge to the water outflow hole 13c. The reversing portion 6 is formed by increasing the curvature of the downstream end portion close to the central water outflow hole 13c, which is the curved end portion of the guide vane 13b, and the imaginary extension line L1 (shown by a dashed line) of this downstream end portion circumscribes the outer edge of the water outflow hole 13c or passes near the circumscribed position.

[0034] FIG. 6 shows a circuit diagram of an example of use of the electric water pump 1 according to this embodiment. 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.

[0035] [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 water flow that rotates while flowing out from the centrifugal side of the first impeller 14 in the first pump chamber 12A of the previous stage and rotates while flowing in from the centrifugal side of the water flow guide plate 13 flows out from the water outlet hole 13c on the central side while rotating. Here, the water flow that is about to flow out from the water outlet hole 13c reverses its rotation direction from the centrifugal side to the water outlet hole 13c at the reversing portion 6 of the guide vane 13b. Therefore, the rotation direction of the water flow that flows from the water outlet hole 13c of the water flow guide plate 13 into the water inlet hole 18a of the second impeller 15 of the second pump chamber 12B of the next stage coincides with the rotation direction of the water flow that flows from the water inlet hole 18a of the second impeller 15 to the centrifugal side.

[0036] In detail, FIG. 7 shows the water flow in the water flow guide plate 13 in this embodiment in a plan view. The water flow in the first impeller 14 rotates counterclockwise from the water inlet hole 16a on the center side toward the centrifugal side as shown by the dashed arrow in FIG. 4 in a plan view. This water flow flows into the centrifugal side of the water flow guide plate 13. Here, the guide vanes 13b of the water flow guide plate 13 are curved so as to be convex toward the centrifugal side along the rotation trajectories of the impellers 14 and 15, and to converge to the water outlet hole 13c. Therefore, as shown by the arrow in FIG. 7, the water flow flowing into the water flow guide plate 13 from the centrifugal side flows in so as to rotate clockwise along the guide vanes 13b, but the rotation direction of the water flow toward the water outlet hole 13c is reversed to counterclockwise by the reversing portion 6. As a result, the water flow out from water outlet hole 13c reverses in a counterclockwise direction, and the water flow flowing into second impeller 15 from water inlet hole 18a of second impeller 15 coincides with the counterclockwise water flow toward the centrifugal side of said impeller 15. Therefore, in multi-stage electric water pump 1 including impellers 14, 15 and water flow guide plate 13 that guides the water flow rotating out from the centrifugal side of first impeller 14 from the centrifugal side to the center side, it is possible to improve the compression efficiency of the water flow flowing from water flow guide plate 13 into the second impeller of the next stage, thereby improving the pump efficiency.

[0037] For comparison, Fig. 8 shows a plan view of a water flow guide plate 63 that does not have a reversing portion 6. As shown in Fig. 8, the guide vane 63b is formed to be curved so as to be convex toward the centrifugal side along the rotation trajectory of the impeller and to converge to the water outflow hole 63c. An imaginary extension line L1 (shown by a dashed line) of the curved end of the guide vane 63b, which is the downstream end close to the central water outflow hole 63c, leads toward or intersects with the water outflow hole 63c.

[0038] FIG. 9 shows a plan view of the water flow in the water flow guide plate 63 in the comparative example. As shown by the arrow in FIG. 9, the water flow flowing into the water flow guide plate 63 from the centrifugal side flows in so as to rotate clockwise along the guide vane 63b, and flows out of the water outlet hole 63c without reversing the rotation direction. Therefore, the water flow flowing into the water inlet hole of the next impeller rotates in the opposite direction to the counterclockwise water flow toward the centrifugal side in the same impeller. Therefore, in the comparative example, the compression efficiency of the water flow is reduced in the next impeller, and the pump efficiency is deteriorated. In this respect, the configuration of this embodiment can solve the above problem. Specifically, in this embodiment, the pump efficiency can be improved by "several percent" compared to the comparative example.

[0039] In addition, according to the configuration of this embodiment, the reversing portion 6 can be obtained by simply increasing the curvature of the downstream end portion close to the central water outlet hole 13c of each guide vane 13b of the water flow guide plate 13. Therefore, the reversing portion 6 can be easily implemented without adding a separate member.

[0040] Furthermore, according to the configuration of this embodiment, the driving force of the electric water pumps 97, 98 used in the cooling system 91 of the electric vehicle 90 is reduced. This makes it possible to improve the energy efficiency of the electric vehicle 90, thereby contributing to energy conservation and carbon neutrality.

[0041] <Another embodiment> It should be noted that the disclosed technology is not limited to the above-described embodiment, and parts of the configuration can be appropriately modified and implemented without departing from the spirit of the disclosed technology.

[0042] In the above embodiment, the electric water pump 1 is configured as a two-stage electric water pump having a first impeller 14 and a second impeller 15, but it can also be configured as a multi-stage electric water pump having three or more impellers. [Industrial Applicability]

[0043] The disclosed technology can be used, for example, in a multi-stage electric water pump used in the cooling system of an electric vehicle. [Explanation of symbols]

[0044] 1 Electric water pump 2. Housing 6 Reversal section 12A First pump room 12B Second pump room 13 Water flow guide board 13b Guide vane 13c Water outflow hole 14 First impeller 14a Impeller blade 15 Second impeller 15a Impeller blade 16 First cover (first impeller) 16a Water inlet hole 18 Second cover (second impeller) 18a Water inlet hole 30 Spindle 90 Electric vehicle 91 Cooling system 97 No. 1 electric water pump 98 No. 2 electric water pump L1 Virtual extension line

Claims

1. The pump includes a housing having a cylindrical shape and including a plurality of pump chambers arranged in an axial direction thereof, Each of the plurality of pump chambers accommodates an impeller that rotates about a support shaft by receiving a rotational driving force and rotates and flows water sucked from a central side toward a centrifugal side. Between adjacent pump chambers, a water flow guide plate is fixed to guide the water flow rotating and flowing out from the centrifugal side of the upstream impeller from the centrifugal side to the center side, In a multi-stage electric water pump, a water flow rotating and flowing out from the centrifugal side of the impeller is guided from the centrifugal side of the water flow guide plate to the central side and pressurized, The impeller is formed with a water inlet hole at its center through which water flows in, and a plurality of impeller blades are arranged at predetermined intervals in a curved vortex shape centered on the water inlet hole, The water flow guide plate is formed with a water outlet hole at its center through which water flows out, and a plurality of guide vanes are provided at predetermined intervals around the water outlet hole in a vortex line curved in the same vortex direction as the impeller vanes, The guide vane has a reversing portion that reverses the rotation direction of the water flow from the centrifugal side to the central side of the water flow guide plate. A multi-stage electric water pump.

2. 2. The multi-stage electric water pump according to claim 1, The guide vane is convexly curved to follow the rotation trajectory of the impeller, The inverted portion is formed by increasing the curvature of a downstream end portion which is an end portion in a curved direction of the guide vane and is close to the center side, and a virtual extension line of the downstream end portion circumscribes an outer edge of the water outflow hole or passes near a circumscribed position. A multi-stage electric water pump.

3. 3. The multi-stage electric water pump according to claim 1, The electric water pump is provided in a cooling system of an electric vehicle. A multi-stage electric water pump.

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