Pump device

Abstract

To provide a pump device capable of reducing a thrust force.SOLUTION: A pump device 1 includes a casing 10 having an inflow part 14 of a fluid L and an outflow part 15 of the fluid L, and an impeller 30 rotatably supported inside the casing 10. The impeller 30 includes an impeller body portion 33, a base 35 provided on the impeller body portion 33, and a plurality of blades 36 provided on the base 35. The impeller body 33 includes an annular recess 39 recessed in the radial direction. A magnet 31 is fixed to the annular recessed part 39, and the magnet 31 is provided with a plurality of through-holes 41 extending in the axial direction.SELECTED DRAWING: Figure 9

Description

[Technical Field]

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

[0002] For example, Patent Document 1 discloses a fluid pump in which multiple fins on an impeller rotate around an axis. This rotation causes cooling water drawn into a casing through an intake port extending along the axis to flow radially outward and then be discharged from the casing through a discharge port. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-332839 Summary of the Invention [Problem to be solved by the invention]

[0004] The cooling water also flows into the lower section that houses the magnet section below the fins. Because the cooling liquid has nowhere to escape, the pressure in the lower section becomes higher than the pressure in the upper section where the fins rotate. This pressure difference exerts an upward thrust force along the axis on the impeller. The thrust force generates contact friction between the impeller and the washer and screw that prevent the impeller from lifting, reducing the performance of the fluid pump.

[0005] The present invention has been made in view of the above-mentioned problems, and one of its objects is to provide a pump device that can reduce thrust force. [Means for solving the problem]

[0006] A pump device according to one aspect of the present invention comprises a casing having a fluid inlet and an outlet, and an impeller rotatably supported inside the casing, the impeller comprising an impeller main body, a base provided on the impeller main body, and a plurality of blades provided on the base, the impeller main body comprising an annular recess that is recessed radially, a magnet fixed to the annular recess, and the magnet comprising a plurality of through holes extending axially. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective view showing a schematic structure of a pump device 1 according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. [Figure 3] FIG. 2 is a perspective view showing a schematic structure of a rotor 32 according to a specific example. [Figure 4] FIG. 2 is a perspective view showing a schematic structure of a rotor 32 according to a specific example. [Figure 5] FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. [Figure 6] FIG. 2 is a perspective view showing a schematic structure of a magnet 31 according to a specific example. [Figure 7] FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. [Figure 8] 10 is a contour diagram showing the distribution of magnetic flux density of the magnet 31. FIG. [Figure 9] 3 is a partially enlarged cross-sectional view corresponding to FIG. 2, illustrating a usage mode of the pump device 1 according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing a schematic structure of a pump device 1 according to an embodiment of the present invention. The 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 attached, for example, to an engine room or motor room of a vehicle. The pump device 1 is used to cool a driving source, such as a vehicle engine or motor, by transferring cooling water to the driving source.

[0009] In the pump device 1, the direction along the axis x is defined as the axial direction. In this axial direction, one side is defined as the upper side, and the other 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 the axis x is defined as the radial direction. In the radial direction, the direction approaching the axis x is defined as the inner circumferential side, and the direction away from the axis x is defined as the outer circumferential side. Furthermore, a circumferential direction is defined around the axis x. The clockwise and counterclockwise directions in the circumferential direction are defined as directions when viewed from above in the axial direction.

[0010] In this example, the pump device 1 includes a casing 10, which is a cylindrical tube having an axis x as a central axis as a whole. The casing 10 includes a lower casing 11 disposed below and an upper casing 12 attached to the lower casing 11 from above. The lower casing 11 and the upper casing 12 are formed by injection molding from a resin material, for example. The lower casing 11 and the upper casing 12 define an internal space of the casing 10.

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

[0012] In the pump device 1, the interior space of the casing 10 is sealed by the lower casing 11 and the upper casing 12. Fluid flows from the inlet 14 through the interior space of the casing 10 and out through the outlet 15. This fluid is a liquid such as a coolant. The liquid includes, for example, water. This water may also include other liquids. The other liquids may include, for example, antifreeze such as propylene glycol or ethylene glycol, rust inhibitors, etc.

[0013] 2 is a cross-sectional view taken along line 2-2 in FIG. 1. As shown in FIG. 2, the casing 10 has an internal space S formed by a lower casing 11 and an upper casing 12. The internal space S has a first space S1 defined within the upper casing 12 and a second space S2 defined within the lower casing 11. In this example, the first space S1 and the second space S2 are both substantially cylindrical spaces centered on the axis x. The first space S1 and the second space S2 are in communication with each other. The diameter of the first space S1 defined in the radial direction is set to be larger than the diameter of the second space S2 also 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, the inner wall 17, the top wall 18, and the outer wall 19 are integrally formed. In this example, the bottom wall 16 is formed in a flat disk shape 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 a cylindrical shape centered on the axis x. The top wall 18 extends outer peripherally from the upper edge of the inner wall 17. The top wall 18 is formed in an annular shape 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 a cylindrical shape centered on the axis x. The inner peripheral surface of the outer wall 19 faces the outer peripheral surface of the inner wall 17 in the radial direction.

[0015] The upper casing 12 has a cover 20 that is disposed within the main body 13 at the base end below the inlet portion 14, and a plurality of spokes 21 that support the cover 20. The cover 20 is formed in a cylindrical shape with its center on the axis x as a whole. The plurality of spokes 21 connect the outer surface of the cover 20 to the inner surface of the inlet portion 14. In this example, three spokes 21 are arranged circumferentially at predetermined intervals. Each spoke 21 is formed, for example, from a flat plate that extends along an imaginary plane that includes the axis x.

[0016] The pump device 1 includes an impeller 30 supported inside the casing 10 so as to be rotatable about an axis x, and a magnet 31 attached to the impeller 30. The impeller 30 and the magnet 31 form a 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 a cover 20 of the upper casing 12. The recess 20a is formed in a concave shape extending from the lower end to the upper end of the cover 20 along the axis x. The lower end of the shaft 22 is fixed to a mounting hole 16a in a bottom wall 16 of the lower casing 11. In this example, the mounting hole 16a passes through the bottom wall 16.

[0017] 3 and 4 are perspective views schematically illustrating the structure of a rotor 32 according to one specific example. FIG. 3 is a perspective view of the rotor 32 as viewed from above in the axial direction, and FIG. 4 is a perspective view of the rotor 32 as viewed from below in the axial direction. FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. 3. The configuration of the rotor 32 will be described below with reference to the aforementioned axis x in FIGS. 3 to 5.

[0018] 2 to 5, the impeller 30 has an impeller body 33 integrally formed from a thermoplastic resin material such as PPS (polyphenylene sulfide). The impeller body 33 has an inner cylindrical portion 34, a base 35, a plurality of blades 36, an outer cylindrical portion 37, and a flange 38. The inner cylindrical portion 34, the base 35, the plurality of blades 36, the outer cylindrical portion 37, and the flange 38 are integrally formed by, for example, injection molding. The plurality of blades 36 form moving blades in the pump device 1.

[0019] The inner cylindrical portion 34 is formed in a cylindrical shape centered on the axis x. The base 35 is formed at the upper end of the inner cylindrical portion 34. The base 35 extends radially from the outer peripheral surface of the inner cylindrical portion 34 in an annular shape. That is, the base 35 is formed in a disk shape centered on the axis x. In this example, the base 35 defines an upper surface that slopes downward from the inner peripheral end connected to the inner cylindrical portion 34 toward the outer peripheral end. The base 35 also defines a lower surface having a portion that approaches the upper surface toward the outer peripheral end. In the axial direction, the lower surface of the base 35 faces the upper surface of the flange 38.

[0020] On the upper surface of the base 35, a plurality of (seven in this example) blades 36 are formed, rising upward from the upper surface. The plurality of blades 36 are arranged in the circumferential direction. In this example, all of the blades 36 have the same shape and dimensions. Each blade 36 extends radially from its inner end adjacent to the inner cylindrical portion 34 to its outer end adjacent to the outer peripheral edge of the base 35. Specifically, each blade 36 is curved in an arc in the counterclockwise direction from the inner end to the outer end. Furthermore, the height of each blade 36 from the upper surface of the base 35 decreases from the inner end to the outer end.

[0021] The outer cylindrical portion 37 is disposed adjacent to the lower end of the inner cylindrical portion 34. The inner peripheral surface of the outer cylindrical portion 37 faces the outer peripheral surface of the inner cylindrical portion 34 in the radial direction. A flange 38 is formed at the upper end of the outer cylindrical portion 37. The flange 38 extends annularly from the upper end of the outer cylindrical portion 37 toward the outer periphery. The outer peripheral surface of the outer cylindrical portion 37 and the lower surface of the flange 38 form an annular recess 39 that is recessed in the radial direction. The aforementioned magnet 31 is fixed to the recess 39. The flange 38 faces the upper surface of the magnet 31 in the axial direction. In this example, the lower surface of the flange 38 contacts the upper surface of the magnet 31.

[0022] FIG. 6 is a perspective view showing a schematic structure of a magnet 31 according to one specific example. Referring to FIGS. 2 to 6 together, the magnet 31 has a main body 40 formed in a cylindrical shape centered on an axis x. The magnet 31 is, for example, a permanent magnet. In the main body 40, regions magnetized to an S pole and regions magnetized to an N pole are defined alternately in the circumferential direction around the axis x (neither is shown). In this example, the diameter defined by the outer circumferential surface of the main body 40 is set to be the same as the diameter defined by the outer circumferential surface of the flange 38 (see FIGS. 3 to 5).

[0023] The magnet 31 is formed in the main body 40 and has a plurality of through holes 41 extending in the axial direction. Each through hole 41 penetrates from the top surface to the bottom surface of the main body 40 in the axial direction. In this example, the magnet 31 is a four-pole permanent magnet, so four through holes 41 are arranged at predetermined intervals in the circumferential direction. Each through hole 41 is arranged in the radial direction at approximately the middle position between the inner and outer circumferential surfaces of the main body 40. As shown in FIGS. 3 and 5, the flange 38 is formed with a plurality of openings 38a that are respectively connected to the plurality of through holes 41 of the magnet 31. The openings 38a penetrate from the top surface to the bottom surface of the flange 38 in the axial direction.

[0024] Returning to FIG. 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 tubular member 42 centered on the axis x. The tubular member 42 is disposed between the inner tubular portion 34 of the impeller main body 33 and the shaft 22. The tubular member 42 is rotatably supported on the shaft 22 about the axis x, and is also supported on the shaft 22 so as to be movable up and down in the axial direction. The tubular member 42 is a so-called sliding bearing. In this example, a predetermined gap is secured in the axial direction between the upper end of the tubular member 42 and the cover 20, and between the lower end of the tubular member 42 and the bottom wall 16.

[0025] 2, the base 35 and blades 36 of the impeller 30 are housed in a first space S1 of the internal space S, while the flange 38 and magnet 31 of the impeller 30 are housed in a second space S2 of the internal space S. In the axial and radial directions, the blades 36 of the impeller 30 face the inner surface of the main body 13 of the upper casing 12 across a predetermined gap. In the radial direction, the outer peripheral surface of the magnet 31 faces the inner peripheral surface of the inner wall 17 of the lower casing 11 across a predetermined gap. 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 across a predetermined gap.

[0026] FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 2. Referring to both FIGS. 2 and 7, a stator 50 is assembled into the lower casing 11. The stator 50 includes 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 formed from a magnetic material. The coil 52 has a winding made of, for example, copper wire. The insulator 53 electrically insulates the stator core 51 from the plurality of coils 52. The insulator 53 is formed from an insulating material such as a resin material.

[0027] The stator core 51 includes 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. The inner circumferential surface of each tooth 55 faces the outer circumferential surface of the magnet 31 of the rotor 32 with a predetermined magnetic gap therebetween, with the inner circumferential surface of the lower casing 11 sandwiched between them. A coil 52 is wound around an insulator 53 covering each tooth 55. While the number of teeth is 12 in this embodiment, this is not limiting. The number of teeth can be any number, such as 6 or 18. The number of poles of the rotor can be changed in accordance with the change in the number of teeth.

[0028] FIG. 8 is a contour diagram showing the distribution of magnetic flux density of magnet 31. This contour diagram shows the distribution of magnetic flux density of magnets 31 and 31A derived by analytical simulation. Magnet 31 is a permanent magnet according to a specific example in which a through hole 41 is formed in main body 40. On the other hand, magnet 31A is a permanent magnet according to a comparative example in which a through hole 41 is not formed in main body 40. Four-pole permanent magnets were used for magnets 31 and 31A.

[0029] As shown in FIG. 8, there was little difference in the magnetic flux density distribution between the magnet 31A of the comparative example and the magnet 31 of the specific example. Specifically, the magnets 31 and 31A have alternating first regions R1, each having a high magnetic flux density, and second regions R2, each having a lower magnetic flux density than the first region R1, arranged in the circumferential direction. In this example, four first regions R1 are arranged at equal intervals in the circumferential direction. The first region R1 is a region that is roughly semicircular and convex toward the outer periphery in a plan view. The second region R2 is located approximately in the radial center of the main body 40 and approximately in the middle between two adjacent first regions R1, R1 in the circumferential direction. The second region R2 is a roughly circular region in a plan view. Between the first region R1 and the second region R2, a third region R3 is defined, which has a magnetic flux density smaller than that of the first region R1 and greater than that of the second region R2.

[0030] Specifically, the first region R1 had a magnetic flux density of approximately 1.0 pu (Per Unit: magnification). The second region R2 had a magnetic flux density of approximately 0.25 pu or less. The third region R3 had a magnetic flux density of approximately 0.25 pu to 1.0 pu. This analytical simulation confirmed that by arranging the through-hole 41 in the second region R2, where the magnetic flux density is low, in the main body 40 of the magnet 31, and by arranging the through-hole 41 inside the outline of the second region R2, it is possible to avoid a deterioration in magnetic flux density.

[0031] FIG. 9 corresponds to FIG. 2 and is a partially enlarged cross-sectional view illustrating a usage mode of the pump device 1 according to one embodiment of the present invention. When current is supplied to the coil 52 of the stator 50, magnetic interaction between the coil 52 and the magnet 31 causes the rotor 32 to rotate clockwise around the axis x. This rotation causes the coolant L to flow into the first space S1 from the inlet 14. The inlet coolant L flows toward the outer periphery due to the rotation of the multiple blades 36, and then flows out from the outlet 15. In this way, the rotation of the rotor 32 pressure-feeds the coolant L from the pump device 1 to, for example, a driving source. In the first space S1, the coolant L is constantly discharged from the outlet 15, so the pressure is relatively low.

[0032] During rotation of the rotor 32 around the axis x, the coolant L also flows from the first space S1 into the second space S2. In the second space S2, the gap between the outer peripheral surface of the magnet 31 and the inner peripheral surface of the inner wall 18 and the gap between the lower surface of the magnet 31 and the upper surface of the bottom wall 16 face each other, with the coolant L interposed therebetween. The coolant L that has flowed into the second space S2 flows from the outer peripheral surface of the magnet 31 into the gap between the lower surface of the magnet 31 and the upper surface of the bottom wall 16. The coolant L then flows axially from bottom to top through the through-hole 41 in the main body 40 of the magnet 31 and the opening 38a in the flange 38. The coolant L is then discharged from the first space S1 through the outflow portion 15. As a result, accumulation of the coolant L in the second space S2 can be suppressed, thereby suppressing a rise in pressure.

[0033] In the pump device 1 described above, the pressure difference between the first space S1 and the second space S2 can be reduced, thereby reducing the upward thrust force acting on the impeller 30, i.e., the rotor 32, in the axial direction and preventing the upper side of the rotor 32 from lifting up in the axial direction. As a result, for example, contact between the upper end of the tubular member 42 and the lower surface of the cover 20 can be reduced, thereby reducing friction due to contact. In this way, deterioration in the rotation performance of the rotor 32 about the axis x can be suppressed, thereby reducing the value of the current supplied to the coil 52 and improving the efficiency of the pump device 1.

[0034] In the pump device 1 described above, the four-pole magnet 31 has a through hole 41 formed in each of the four second regions R2 where the magnetic flux density is low. However, the number of through holes 41 may be any number other than four, such as one or more. The diameter of the through hole 41 is set to a size equal to or smaller than the dimensions of the second region R2. The cross-sectional shape of the through hole 41 in an imaginary plane perpendicular to the axis x may be circular, rectangular, elliptical, oval, or any other shape that allows the passage of the fluid, i.e., the coolant L. The diameter or shape of the through hole 41 may change midway along the axial direction. For example, the opening of the through hole 41 may be set to be smaller / larger on the upper and / or lower surfaces of the main body 40 of the magnet 31.

[0035] Furthermore, in the pump device 1 described above, the opening 38a of the flange 38 has the same diameter and cross-sectional shape as the through hole 41 of the magnet 31, but it may be formed with other diameters and cross-sectional shapes. For example, the opening 38a may be a recess that is recessed from the outer peripheral edge of the flange 38 toward the inner peripheral side. The opening 38a may also have a diameter larger than the diameter of the through hole 41. Furthermore, as long as the lower surface of the flange 38 abuts against at least a portion of the upper surface of the magnet 31, the outer peripheral edge of the flange 38 may be positioned radially inward of the position where the through hole 41 is formed. In other words, the through hole 41 may be positioned radially outward of the outer peripheral edge of the flange 38.

[0036] Furthermore, the pump device 1 may have one or more additional through holes formed in the axial direction, penetrating from the upper surface to the lower surface of the base 35 of the impeller 30. These one or more additional through holes allow the movement of the coolant L, i.e., fluid, between the first space S1 and the second space S2. As a result, for example, fluid can move from the second space S2 to the second space S1, further reducing the pressure difference between the first space S1 and the second space S2. Note that the position of this through hole may at least partially overlap with the position of the through hole 41 of the magnet 31 or the position of the opening 38a of the flange 38 in the axial direction, or may be shifted from the position.

[0037] Furthermore, in the pump device 1, the magnet 31 may be formed from a bonded magnet. A bonded magnet is formed by molding a thermosetting resin material mixed with magnetic powder, for example, by injection molding. Therefore, by simultaneously forming the through-hole 41 in the main body 40 of the magnet 31 during injection molding, the manufacture of the magnet 31 can be facilitated.

[0038] Although the present invention has been described above through the above embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0039] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. Furthermore, the above-described embodiments do not limit the scope of the present invention, and the present invention may include any and all applications. The components of the above-described embodiments, as well as their arrangement, materials, conditions, shape, size, etc., are not limited to those illustrated and may be modified as appropriate. For example, the present invention includes differences that arise during implementation due to manufacturing tolerances, etc. Furthermore, components illustrated in different embodiments may be partially substituted or combined within the scope of technical inconsistency. Furthermore, the various configurations may be selectively combined as appropriate to achieve at least some of the above-described problems and effects. [Explanation of symbols]

[0040] 1 pump device, 10 casing, 11 lower casing, 12 upper casing, 13 main body, 14 inlet portion, 15 outlet portion, 16 bottom wall, 16a mounting hole, 17 inner wall, 18 top wall, 19 outer wall, 20 cover, 20a recess, 21 spokes, 22 shaft, 30 impeller, 31, 31A magnet, 31A magnet, 32 rotor, 33 impeller main body, 34 inner cylinder portion, 35 base, 36 blade, 37 outer cylinder portion, 38 flange, 38a opening, 39 recess, 40 main body, 41 through hole, 42 cylindrical member, 50 stator, 51 stator core, 52 coil, 53 insulator, 54 annular portion, 55 teeth, L coolant (fluid), R1 Region with high magnetic flux density (first region), R2 Region with low magnetic flux density (second region), R3 Third region, S Internal space, S1 First space, S2 Second space, x axis

Claims

1. a casing having a fluid inlet and a fluid outlet; an impeller rotatably supported inside the casing, The impeller includes an impeller body, a base provided on the impeller body, and a plurality of blades provided on the base, The impeller body portion includes an annular recess portion recessed in a radial direction, A magnet is fixed in the annular recess, The magnet has a plurality of through holes extending in the axial direction.

2. The impeller body includes a flange facing the magnet in the axial direction, The flange has a plurality of openings that communicate with the plurality of through holes of the magnet.

2. The pump device of claim 1.

3. The magnet has regions of high magnetic flux density and regions of low magnetic flux density alternately in the circumferential direction, The through hole is disposed in the region where the magnetic flux density is low.

3. A pump device according to claim 1 or 2.

4. the casing includes a cylinder that accommodates the impeller body, The cylinder has a bottom wall facing the magnet in the axial direction, the bottom wall faces the through-hole with the fluid interposed therebetween; 2. The pump device of claim 1.

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