Pump device

Abstract

A pump device (1) is provided with a casing (10) having an inflow part (14) for a fluid and an outflow part (15) for the fluid, and an impeller (30) rotatably supported inside the casing (10). The impeller (30) is provided with a plurality of first blades (36) and a plurality of second blades (37), and the plurality of first blades (36) and the plurality of second blades (37) are aligned in the axial direction.

Description

Pump device

[0001] The present invention relates to a pump device.

[0002] For example, Patent Document 1 discloses a pump for vehicle mounting. In this pump, an integrally formed impeller and rotor are rotatably supported in a housing via a shaft portion. By the rotation of the impeller, the cooling water flowing into the housing from the suction pipe is pressurized and flows out from the discharge pipe.

[0003] Japanese Patent Application Laid-Open No. 2009-68444

[0004] The cooling water also flows into the lower part of the housing that houses the rotor. Since there is no escape space for the cooling water in this lower part, the pressure in the lower part becomes higher than the pressure in the upper part of the housing that houses the impeller. This pressure difference acts on the impeller as an upward thrust force along the axis. The thrust force causes contact friction between the impeller and the support portion of the shaft portion, thereby degrading the performance of the pump.

[0005] The present invention has been made in view of the above problems, and one of the problems is to provide a pump device capable of reducing the thrust force.

[0006] The pump device according to one aspect of the present invention includes a casing having an inflow portion of a fluid and an outflow portion of the fluid, and an impeller main body portion provided with an impeller rotatably supported inside the casing. The impeller includes a plurality of first blades and a plurality of second blades, and the plurality of first blades and the plurality of second blades are arranged side by side in the axial direction.

[0007] This is a schematic perspective view showing the structure of a pump device 1 according to one embodiment of the present invention. This is a cross-sectional view along line 2-2 in Figure 1. This is a schematic perspective view showing the structure of a rotor 32 according to one specific example. This is a schematic perspective view showing the structure of a rotor 32 according to one specific example. This is a cross-sectional view along line 5-5 in Figure 3. This is a cross-sectional view along line 6-6 in Figure 5. This is a cross-sectional view along line 7-7 in Figure 2. This is a partially enlarged cross-sectional view corresponding to Figure 2, for explaining the usage of the pump device 1 according to one embodiment of the present invention. This is a graph showing the results of fluid analysis to verify the effect of the impeller. This is a schematic perspective view showing the structure of an impeller 30A according to another specific example. This is a schematic perspective view showing the structure of an impeller 30A according to another specific example. This is a cross-sectional view along line 12-12 in Figure 10. This is a perspective cross-sectional view along line 13-13 in Figure 10. This is a schematic perspective view showing the structure of an impeller 30A according to another specific example. This is a graph showing the results of simulation to verify the effect of the impeller.

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings. Figure 1 is a schematic perspective view showing the structure of a pump device 1 according to an embodiment of the present invention. This pump device 1 is, for example, a water pump. A water pump is a centrifugal pump for transferring (pressurizing) a fluid, i.e., cooling water. The pump device 1 is installed, for example, in the engine room or motor room of a vehicle. The pump device 1 is used, for example, to cool a drive source such as the engine or motor of a vehicle by transferring cooling water to the drive source.

[0009] In pump device 1, the direction along axis x is defined as the axial direction. In this axial direction, one side is defined as the upper side, and the other side opposite to the upper side is defined as the lower side. The upper and lower sides do not necessarily coincide with the upper and lower sides in the direction of gravity. Furthermore, the direction perpendicular to axis x is defined as the radial direction. In the radial direction, the direction approaching axis x is defined as the inner circumference, and the direction moving away from axis x is defined as the outer circumference. In addition, a circumferential direction is defined around axis x. The clockwise and counterclockwise directions in the circumferential direction are defined as the direction when viewed from the upper side in the axial direction.

[0010] In this example, the pump device 1 includes a casing 10 that is formed in a cylindrical shape with axis x as its central axis. The casing 10 has a lower casing 11 positioned on the lower side in the axial direction, and an upper casing 12 that is attached to the lower casing 11 from the upper side in the axial direction. The lower casing 11 and the upper casing 12 are formed, for example, from a resin material by injection molding. The internal space of the casing 10 is defined by the lower casing 11 and the upper casing 12.

[0011] The upper casing 12 has a main body portion 13 and an inlet portion 14 and an outlet portion 15 integrally formed on the main body portion 13. The main body portion 13 is formed in a generally disc shape, for example, with axis x as the center. The inlet portion 14 protrudes upward in a cylindrical shape from the main body portion 13 along axis x. The inlet portion 14 allows fluid to flow into the internal space of the casing 10. The outlet portion 15 is formed in a cylindrical shape along the tangent to a virtual circle centered on axis x. The outlet portion 15 allows fluid to flow out from the internal space of the casing 10. The outlet portion 15 protrudes outward from the main body portion 13 along the tangent.

[0012] In the pump device 1, the internal space of the casing 10 is sealed by covering the upper opening of the lower casing 11 with the upper casing 12. The fluid flows into the casing 10 from the inlet 14 along axis x, and then flows out from the outlet 15 along the tangent to a virtual circle centered on axis x through the internal space of the casing 10. This fluid is a liquid, such as a coolant. The liquid may include, for example, water. This water may contain other liquids. These other liquids may include, for example, antifreeze such as propylene glycol or ethylene glycol, or rust inhibitors. Furthermore, the coolant or other liquid may have insulating properties.

[0013] Figure 2 is a cross-sectional view along line 2-2 in Figure 1. As shown in Figure 2, an internal space S is formed within the casing 10 by the lower casing 11 and the upper casing 12. The internal space S consists of a first space S1 defined within the upper casing 12 and a second space S2 defined within the lower casing 11. In this example, both the first space S1 and the second space S2 are generally cylindrical spaces centered on axis x. The first space S1 and the second space S2 are in communication with each other. The dimensions of the first space S1, defined in the radial direction, are set to be larger than the dimensions of the second space S2, which is similarly defined in the radial direction.

[0014] The lower casing 11 has a bottom wall 16, an inner wall 17, a top wall 18, and an outer wall 19. The bottom wall 16, inner wall 17, top wall 18, and outer wall 19 are formed integrally. In this example, the bottom wall 16 is formed in the shape of a flat disc perpendicular to the axis x. The inner wall 17 extends upward from the outer peripheral edge of the bottom wall 16. The inner wall 17 is formed in the shape of a cylinder centered on the axis x. The top wall 18 extends outward from the upper edge of the inner wall 17. The top wall 18 is formed in the shape of an annular ring centered on the axis x. The outer wall 19 extends downward from the outer peripheral edge of the top wall 18. The outer wall 19 is formed in the shape of a cylinder centered on the axis x. In the radial direction, the inner circumferential surface of the outer wall 19 faces the outer circumferential surface of the inner wall 17.

[0015] The upper casing 12 further includes a cover 20 disposed within the main body 13 and a plurality of spokes 21 supporting the cover 20. In this example, the cover 20 is positioned at a location where it enters the first space S1 of the main body 13 from the inlet 14 along the axis x. The cover 20 is formed as a whole in a cylindrical shape centered on the axis x. The plurality of spokes 21 connect the outer surface of the cover 20 to the inner surface of the inlet 14. In this example, three spokes 21 are arranged at predetermined intervals in the circumferential direction. Each spoke 21 is formed in a flat plate shape, for example, extending along a virtual plane containing the axis x.

[0016] The pump device 1 comprises an impeller 30 rotatably supported inside the casing 10 around an axis x, and a magnet 31 attached to the impeller 30. The impeller 30 and magnet 31 constitute the rotor 32 of the pump device 1. The impeller 30 is rotatably mounted on a cylindrical shaft 22 extending along the axis x. The upper end of the shaft 22 is fixed to a recess 20a in the cover 20 of the upper casing 12. The recess 20a is formed in a concave shape along the axis x from the lower end to the upper end of the cover 20. The lower end of the shaft 22 is fixed to a mounting hole 16a in the bottom wall 16 of the lower casing 11. In this example, the mounting hole 16a penetrates the bottom wall 16.

[0017] Figures 3 and 4 are schematic perspective views showing the structure of a rotor 32 according to one specific example. Figure 3 is a perspective view of the rotor 32 as seen from above in the axial direction, and Figure 4 is a perspective view of the rotor 32 as seen from below in the axial direction. Figure 5 is a cross-sectional view along line 5-5 in Figure 3. Referring together to Figures 3 to 5, the impeller 30 has an impeller body portion 33 formed from a thermoplastic resin material, such as PPS (polyphenylene sulfide). The impeller body portion 33 is integrally formed, for example, by injection molding. The impeller body portion 33 has an inner cylinder portion 34, a base 35, a plurality of first blades 36, a plurality of second blades 37, an outer cylinder portion 38, and a flange 39.

[0018] The inner cylinder portion 34 is formed in a cylindrical shape with axis x as the center. The base 35 extends in an annular manner from the upper end of the inner cylinder portion 34 toward the outer circumference. That is, the base 35 is formed in a disc shape with axis x as the center. In this example, the base 35 defines a first surface 35a and a second surface 35b that are opposite each other. The first surface 35a faces upward, and the second surface 35b faces downward. That is, the first surface 35a is on the opposite side of the second surface 35b in the axial direction. In this example, the first surface 35a has a portion on the inner circumference that slopes downward as it moves toward the outer circumference. The second surface 35b has a portion on the outer circumference that approaches the upper surface as it moves toward the outer circumference.

[0019] The first surface 35a of the base 35 is provided with a plurality (seven in this example) of first blades 36 that rise upward from the first surface 35a. The first surface 35a supports the first blades 36. The plurality of first blades 36 are arranged in the circumferential direction. In this example, all first blades 36 have the same shape and dimensions. Each first blade 36 extends generally radially from the inner end adjacent to the inner cylinder portion 34 to the outer end adjacent to the outer edge of the base 35. Each first blade 36 has a portion that curves in an arc in the counterclockwise direction from the inner end to the outer end. In addition, each first blade 36 decreases in height from the upper surface of the base 35 from the inner end to the outer end. The plurality of first blades 36 constitute a so-called centrifugal impeller.

[0020] Figure 6 is a cross-sectional view along line 6-6 in Figure 5. Referring to Figure 6, the second surface 35b of the base 35 is provided with a plurality (seven in this example) of second blades 37 that rise downward from the second surface 35b. The second surface 35b supports the second blades 37. The plurality of first blades 36 and the plurality of second blades 37 are aligned in the axial direction. The plurality of second blades 37 are arranged in the circumferential direction. In this example, all second blades 37 have the same shape and dimensions. Each second blade 37 extends radially from the inner end adjacent to the inner cylinder portion 34 to the outer end adjacent to the outer edge of the base 35. When viewed from above, each second blade 37 has a portion that curves in an arc in a counterclockwise direction from the inner end to the outer end.

[0021] In this example, in a plan view in the axial direction, the contours of the first blade 36 and the second blade 37 coincide. That is, the multiple first blades 36 and the multiple second blades 37 are arranged in the same position in the axial direction. Each second blade 37 has a constant height from the second surface 35b from the inner end to the outer end. In this example, as is clear from Figure 5, the height of the first blade 36 from the first surface 35a is set to be greater than the height of the second blade 37 from the second surface 35b. In the axial direction, the second surface 35b is at least partially opposite the upper surface of the flange 39. The second blades 37 are opposite the upper surface of the flange 39 in the axial direction with a gap between them. The multiple second blades 37 constitute a so-called centrifugal impeller.

[0022] The outer cylinder portion 38 is positioned adjacent to the lower end of the inner cylinder portion 34. In the radial direction, the inner circumferential surface of the outer cylinder portion 38 faces the outer circumferential surface of the inner cylinder portion 34. A flange 39 is formed at the upper end of the outer cylinder portion 38. The flange 39 extends annularly from the upper end of the outer cylinder portion 38 outward. The flange 39 is located at a different position from the base 35 in the axial direction. The radial dimensions of the flange 39 are smaller than the radial dimensions of the base 35. The outer circumferential surface of the outer cylinder portion 38 and the lower surface of the flange 39 form an annular recess 40 that is recessed in the radial direction. The aforementioned magnet 31 is fixed in the recess 40.

[0023] The magnet 31 is formed in a cylindrical shape, for example, with axis x as its center. The magnet 31 is, for example, a permanent magnet. The magnet 31 has alternating regions defined in the circumferential direction around axis x, regions magnetized as south poles and regions magnetized as north poles. In this example, the dimensions defined on the outer surface of the magnet 31 are set to be the same as the dimensions defined on the outer surface of the flange 38. The flange 39 faces the upper surface of the magnet 31 in the axial direction. In this example, the lower surface of the flange 39 is in contact with the upper surface of the magnet 31.

[0024] Referring together to Figures 5 and 6, the impeller body 33 has one or more through holes 41 that penetrate the base 35 in the axial direction. In this example, three through holes 41 are arranged at predetermined intervals in the circumferential direction. The impeller body 33 also has one or more through holes 42 that penetrate the flange 39 in the axial direction. In this example, four through holes 42 are arranged at predetermined intervals in the circumferential direction. Each through hole 42 is located between the inner cylinder portion 34 and the outer cylinder portion 38 in the radial direction. In the axial direction, the positions of some of the through holes 41 may coincide with the positions of the through holes 42, and the positions of all the through holes 41 may not coincide with the positions of the through holes 42.

[0025] Returning to Figure 2, the rotor 32 is housed in the internal space S of the casing 10. The impeller 30 is rotatably supported on the shaft 22 via a cylindrical member 43 centered on axis x. The cylindrical member 43 is positioned between the inner cylindrical portion 34 of the impeller body 33 and the shaft 22. The cylindrical member 43 is rotatably supported on the shaft 22 around axis x and is also supported on the shaft 22 so as to be movable up and down in the axial direction. The cylindrical member 43 is a so-called sliding bearing. In this example, predetermined gaps are secured in the axial direction between the upper end of the cylindrical member 43 and the cover 20, and between the lower end of the cylindrical member 43 and the bottom wall 16.

[0026] As is clear from Figure 2, the base 35 of the impeller 30 is housed in the first space S1 of the internal space S, while the flange 39 and magnet 31 of the impeller 30 are housed in the second space S2 of the internal space S. In the axial and radial directions, the first blades 36 of the impeller 30 face the inner surface of the main body portion 13 of the upper casing 12 with a predetermined gap between them. In the radial direction, the outer circumferential surface of the magnet 31 faces the inner circumferential surface of the inner wall 17 of the lower casing 11 with a predetermined gap between them. Also, in the axial direction, the lower surface of the magnet 31 faces the upper surface of the bottom wall 16 of the lower casing 11 with a predetermined gap between them.

[0027] Figure 7 is a cross-sectional view along line 7-7 in Figure 2. Referring to both Figure 2 and Figure 7, a stator 50 is incorporated into the lower casing 11. The stator 50 comprises a stator core 51, a plurality of coils 52, and an insulator 53. The stator core 51 is formed from a laminate of a plurality of thin plates stacked in the axial direction. The laminate is made of a magnetic material. The coils 52 have windings, for example, made of copper wire. The insulator 53 electrically insulates the stator core 51 from the plurality of coils 52. The insulator 53 is made of an insulating material, for example, a resin material.

[0028] The stator core 51 comprises an annular portion 54 fixed to the inner circumferential surface of the outer wall 19, and a plurality of teeth 55. The annular portion 54 is defined in an annular shape around the axis x. Each tooth 55 protrudes inward from the inner circumferential surface of the annular portion 54. In this example, 12 teeth 55 are arranged at equal intervals in the circumferential direction. Each tooth 55 faces the outer circumferential surface of the magnet 31 of the rotor 32 with a predetermined magnetic gap, with the inner wall 17 of the lower casing 11 in between. The insulator 53 covering each tooth 55 is wound with the windings of the coil 52. In this example, the number of teeth is 12, but it is not limited to this. The number of teeth can be any number, such as 6 or 18. The number of poles of the rotor can also be changed in accordance with the change in the number of teeth.

[0029] Figure 8 corresponds to Figure 2 and is a partially enlarged cross-sectional view illustrating the usage of a pump device 1 according to one embodiment of the present invention. When current is supplied to the coil 52 of the stator 50, the magnetic interaction between the coil 52 and the magnet 31 causes the first blades 36 of the rotor 32, i.e., the impeller 30, to rotate clockwise around the axis x. This rotation of the first blades 36 causes the coolant L to flow into the first space S1 from the inlet 14. The incoming coolant L flows outwards through the multiple first blades 36 on the first surface 35a side of the base 35, and then flows out from the outlet 15. In this way, the coolant L is pumped from the pump device 1 to, for example, a drive source.

[0030] As the rotor 32 rotates around axis x, the coolant L attempts to flow from the first space S1 into the second space S2. As the rotor 32 rotates, the second blades 37 of the impeller 30 rotate clockwise around axis x, so on the second surface 35b side of the base 35, the coolant L flows outwards through the gaps between the multiple second blades 37. In this example, as is clear from Figure 8, since the second blades 37 are positioned adjacent to the boundary between the first space S1 and the second space S2, the flow of coolant L toward the outer circumference due to the rotation of the second blades 37 can suppress the inflow of coolant L from the first space S1 into the second space S2. At the same time, the coolant L that has flowed into the second space S2 is returned from the second space S2 towards the first space S1. This can suppress the stagnation of coolant L within the second space S2.

[0031] In the pump device 1 described above, the inflow of coolant L from the first space S1 to the second space S2 can be suppressed, thereby reducing the upward thrust force acting on the impeller 30, i.e., the rotor 32, in the axial direction, and preventing the rotor 32 from lifting upward in the axial direction. As a result, contact between, for example, the upper end of the cylindrical member 43 and the lower surface of the cover 20 can be reduced, thereby reducing contact friction. In this way, the deterioration of the rotational performance of the rotor 32 around the axis x can be suppressed, so the current value supplied to the coil 52 can be reduced, and the efficiency of the pump device 1 can be improved.

[0032] Furthermore, the impeller 30 has one or more through holes 41 that penetrate the base 35 in the axial direction, and one or more through holes 42 that penetrate the flange 39 in the axial direction. With these through holes 41 and 42, the coolant L in the second space S2 can flow from the space below the impeller 30 through the space between the inner cylinder portion 34 and the outer cylinder portion 38 and through the through holes 42 in the axial direction from bottom to top. Subsequently, the coolant L flows upward from the second space S2 to the first space S1 through the through holes 41 due to the rotation of the second blade 37. As a result, the pressure difference between the first space S1 and the second space S2 can be reduced, so the upward thrust force acting on the rotor 32 can be further reduced.

[0033] Figure 9 is a graph showing the results of a fluid analysis to verify the effect of the impeller. For the fluid analysis, the aforementioned impeller 30 was used as a specific example, while an impeller without the second blade 37 was used as a comparative example. The comparative example was configured the same as the impeller 30 except for the second blade 37. Through the fluid analysis, the PQ characteristics (head) [m] and axial thrust force [N] were calculated for both the specific example and the comparative example. As a result, despite increases and decreases in the flow rate of the coolant, there was almost no change in the PQ characteristics for both the specific example and the comparative example. On the other hand, the thrust force decreased as the flow rate increased, but overall, it was confirmed that the thrust force of the specific example was reduced by approximately 40% compared to the comparative example.

[0034] Figures 10 and 11 are perspective views schematically showing the structure of an impeller 30A according to another specific example. Figure 10 is a perspective view of the impeller 30A as seen from above in the axial direction, and Figure 11 is a perspective view of the impeller 30A as seen from below in the axial direction. Figure 12 is a cross-sectional view along line 12-12 in Figure 10. Figure 13 is a perspective cross-sectional view along line 13-13 in Figure 10. Figures 10 to 13 show the impeller 30A with the magnet 31 removed. Furthermore, for the impeller 30A, the same reference numerals are used for components similar to those of the impeller 30 described above, and redundant explanations are omitted here.

[0035] Referring to Figures 10 to 13, the impeller 30A differs from the aforementioned impeller 30 in that the outer cylinder portion 38 and the through hole 42 are omitted, and multiple second blades 37 are provided between the base 35 and the flange 39. That is, in the impeller 30A, the multiple second blades 37 are integrally formed on the outer circumferential surface of the inner cylinder portion 34 instead of the second surface 35b of the base 35. The multiple second blades 37 face the second surface 35b of the base 35 with a gap in between. In this example, seven second blades 37 are arranged in the circumferential direction. These multiple second blades 37 constitute a so-called axial flow impeller.

[0036] Specifically, each second blade 37 extends spirally in a counterclockwise direction around the axis x. Each second blade 37 extends spirally in a counterclockwise direction from the bottom to the top in the axial direction. The second blade 37 has a first surface 37a facing upward and a second surface 37b facing downward while facing away from the first surface 37a. The first surface 37a and the second surface 37b are formed from curved surfaces that are convex in the downward and counterclockwise directions. In this example, second blades 37 that are adjacent to each other in the circumferential direction are arranged so as not to overlap each other in the axial direction. The radial dimensions of the second blades 37 are smaller than the radial dimensions of the base 35 and are set to be the same as the radial dimensions of the flange 39.

[0037] Figure 14 is a schematic perspective view showing the structure of an impeller 30A according to another specific example. Referring together to Figures 10, 11, and 14, the impeller 30A has one or more through holes 41 that penetrate the base 35 in the axial direction. In this example, one through hole 41 is formed between a pair of circumferentially adjacent first blades 36, 36 at the inner circumferential edge of the base 35 adjacent to the inner cylinder portion 34. In this example, seven through holes 41 are arranged at equal intervals in the circumferential direction. Each through hole 41 faces the first surface 37a of each second blade 37 in the axial direction. Specifically, as shown in Figure 11, each through hole 41 faces the upper region in the axial direction on the first surface 37a of the second blade 37.

[0038] The impeller 30A described above is incorporated into the pump device 1 in place of the impeller 30. As before, when the first blade 36 of the impeller 30A rotates clockwise around the axis x, the coolant L flows into the first space S1 from the inlet 14. The coolant L that flows in passes between the multiple first blades 36 and flows out to the outer circumference, and then flows out from the outlet 15. At the same time, when the second blade 37 of the impeller 30A rotates clockwise around the axis x, the action of the second blade 37 generates a flow of coolant L that is directed upward along the axial direction. This flow generates a downward thrust force on the impeller 30A along the axial direction. As a result, the upward thrust force generated on the impeller 30A can be weakened.

[0039] Furthermore, since the through hole 41 faces the first surface 37a of the second blade 37 in the axial direction, the axial flow of coolant L generated by the second blade 37 is reliably directed towards the through hole 41. As a result, the coolant L in the second space S2 flows upward from the second space S2 to the first space S1 through the through hole 41. In this way, the stagnation of coolant L in the second space S2 can be suppressed. As a result, the pressure difference between the first space S1 and the second space S2 can be reduced. The second blade 37 may also be connected to the flange 39 in the axial direction.

[0040] Figure 15 is a graph showing the simulation results for verifying the effect of the impeller. For the simulation, the aforementioned impeller 30A was used as a specific example, while an impeller without the second blade 37 was used as a comparative example. The comparative example was configured the same as the impeller 30 except for the second blade 37. In both the specific example and the comparative example, the radial dimension of the second blade 37 was set to about half the radial dimension of the first blade 36. As a result, the thrust force decreased in both the comparative example and the specific example as the flow rate increased, but it was confirmed that the thrust force was reduced by about 10% overall in the specific example compared to the comparative example, regardless of the increase or decrease in flow rate.

[0041] Although the present invention has been described above through the embodiments described above, the technical scope of the present invention is not limited to the scope described in the embodiments above. It will be obvious to those skilled in the art that various modifications or improvements can be made to the embodiments described above. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0042] The embodiments described above are for the purpose of facilitating understanding of the present invention and are not intended to limit its interpretation. Furthermore, the embodiments described above do not limit the scope of application of the present invention, and the present invention may encompass anything as its target application. The components of the above embodiments, as well as their arrangement, materials, conditions, shapes, and sizes, are not limited to those exemplified and can be modified as appropriate. For example, the present invention includes differences that arise in the implementation of manufacturing tolerances, etc. Furthermore, components shown in different embodiments can be partially substituted or combined to the extent that they do not contradict each other in a technical sense. In addition, each configuration can be selectively combined as appropriate to achieve at least some of the problems and effects described above.

[0043] 1 Pump device, 10 Casing, 11 Lower casing, 12 Upper casing, 13 Main body, 14 Inlet, 15 Outlet, 16 Bottom wall, 16a Mounting hole, 17 Inner wall, 18 Top wall, 19 Outer wall, 20 Cover, 20a Recess, 21 Spoke, 22 Shaft, 30, 30A Impeller, 31 Magnet, 32 Rotor, 33 Impeller body, 34 Inner cylinder, 35 Base, 36 First blade, 37 Second blade, 38 Outer cylinder, 39 Flange, 40 Recess, 41, 42 Through hole, 43 Cylindrical member, 50 Stator, 51 Stator core, 52 Coil, 53 Insulator, 54 Annular part, 55 Teeth, L Coolant (fluid), S Internal space, S1 First space, S2 Second space, x axis line

Claims

1. A pump device comprising: a casing having a fluid inlet and a fluid outlet; and an impeller rotatably supported inside the casing, wherein the impeller comprises a plurality of first blades and a plurality of second blades, and the plurality of first blades and the plurality of second blades are aligned in the axial direction.

2. The pump device according to claim 1, wherein the impeller comprises a base, and the plurality of first blades are provided on the base.

3. The pump device according to claim 2, wherein the base comprises, in the axial direction, a first surface that supports the plurality of first blades and a second surface opposite to the first surface, and the second surface of the base supports the plurality of second blades.

4. The pump device according to claim 2, wherein the impeller has a flange located in a different position from the base in the axial direction, and the plurality of second blades are provided between the base and the flange in the axial direction.

5. The pump device according to claim 2, wherein the radial dimension of the flange is smaller than the radial dimension of the base.

6. The pump device according to claim 2, wherein in the axial direction, the second blade faces the base with a gap between them.

7. The pump device according to claim 2, wherein the base has a through hole that penetrates in the axial direction, and in the axial direction, the through hole faces the second blade.

8. The pump device according to claim 1 or 2, wherein the plurality of second blades have curved portions.

Images