electric pump

Abstract

To inhibit contaminants from entering a bearing to prevent failure in rotation even if the contaminants are mixed in fluid suctioned by an electric pump.SOLUTION: An electric pump 1 includes: a first passage 81 communicating with a high pressure area in a housing 5 and extending to a side opposite to an impeller 4 of a stator core 20; a second passage 82 branched from the first passage 81 and extending to one end of a rotary shaft 24 toward a radial inner side of a motor 2; a third passage 83 communicating with the second passage 82 and extending between the rotary shaft 24 and a bearing 25; and a fourth passage 84 located in the rotary shaft 24. A portion, which is opposite to the impeller 4, of the first passage 81 and the third passage 83 are connected to the fourth passage 84 at the other end part of the rotary shaft 24. The fourth passage 84 communicates with a low pressure area in the housing 5 at the one end of the rotary shaft 24.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an electric pump that draws in and discharges fluid by the rotation of an impeller. [Background technology]

[0002] For example, Patent Documents 1 and 2 disclose centrifugal pumps that include a pump chamber that houses an impeller and an electric motor that rotates a rotating shaft to which the impeller is fixed. The rotating shaft of the centrifugal pump in Patent Document 1 is hollow, and the interior of the rotating shaft forms an outlet passage for fluid that extends in the axial direction. One end of the outlet passage communicates with the low-pressure region of the pump chamber, and the other end communicates with the high-pressure region.

[0003] Patent Document 3 discloses a fluid pump equipped with an axial gap motor in which a rotor and a stator core are arranged to face each other in the direction of the rotation axis. In this fluid pump, a water channel is formed along the end face of the stator core facing the rotor, and a water channel is formed along the end face of the stator core opposite the rotor, and fluid can flow through these water channels. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 98357 [Patent Document 2] Japanese Patent Application Publication No. 2019-94794 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-299975 Summary of the Invention [Problem to be solved by the invention]

[0005] By employing a hollow shaft as the rotating shaft as in Patent Documents 1 and 2, it is possible to circulate fluid inside the rotating shaft, thereby improving the cooling efficiency of each part. Also, by allowing fluid to circulate on both axial sides of the stator core that constitutes the axial gap motor as in Patent Document 3, it is possible to improve the cooling efficiency of each part.

[0006] Incidentally, the fluid pumped by an electric pump may contain foreign matter called contaminants, and even if some of the contaminants can be captured by a filter or the like, small contaminants may not be captured and may be sucked into the electric pump. The fluid containing the contaminants sucked into the electric pump flows through the cooling flow paths of Patent Documents 1 to 3, but since the cross-sectional area of ​​the cooling flow path is relatively large, the inclusion of small contaminants does not pose a problem.

[0007] However, electric pumps also require lubrication of the bearings that rotatably support the rotating shaft. If the bearings are lubricated using the fluid drawn into the electric pump, it would be possible to cool the bearings as well, which is desirable. However, since only an extremely small clearance can be tolerated between the rotating shaft and the bearings to prevent rattle, small contaminants can get into the bearings and cause rotation problems.

[0008] The present disclosure has been made in consideration of such points, and its purpose is to prevent contaminants from entering the bearings and causing rotation problems even if they are mixed into the fluid drawn in by the electric pump. [Means for solving the problem]

[0009] To achieve the above object, a first aspect of the present disclosure can be based on the premise of a centrifugal electric pump including an impeller rotationally driven by an axial gap motor and a housing that accommodates the impeller. The axial gap motor includes a stator core fixed to a motor housing, a coil wound around the stator core, a first magnet and a first back yoke fixed to the impeller, a support shaft formed of a hollow shaft, and a bearing that receives the support shaft, one member of the support shaft and the bearing is fixed to the motor housing, the other member is rotatable relative to the one member, and the impeller is fixed to one end of the other member, one end face of the stator core and the first magnet are arranged side by side with a predetermined gap in the direction of the rotation center line, and the axial gap motor communicates with a high-pressure region formed on the impeller side of the stator core in the housing, and the impeller of the stator core is connected to the high-pressure region. a first flow path extending in the direction of the rotation center line to the side opposite the impeller and having a cross-sectional diameter, when converted into a circle, larger than the gap; a second flow path branching from the first flow path and extending through the gap toward the radially inner side of the motor to one end of the spindle; a third flow path communicating with the radially inner part of the second flow path and extending between the spindle and the bearing to the other end of the spindle; and a fourth flow path extending inside the spindle in the direction of the rotation center line, a part of the first flow path opposite the impeller and a part of the third flow path on the side of the other end of the spindle are connected to the fourth flow path at the other end of the spindle, and the fourth flow path is in communication with a low-pressure region formed in the housing at one end of the spindle.

[0010] With this configuration, when the impeller is rotated by the axial gap motor, fluid within the housing is sucked in near the impeller's rotational centerline and discharged radially outward, creating a low-pressure region near the impeller's rotational centerline and a high-pressure region radially outward from the impeller within the housing. Because the first flow path is connected to the high-pressure region, some of the fluid in the high-pressure region flows into the first flow path and flows to the opposite side of the stator core from the impeller. The fluid flowing through this first flow path cools the stator core and other components. Fluid also flows into a second flow path branching from the first flow path, and this fluid flows through a third flow path, enabling bearing lubrication and cooling.

[0011] In this case, the second flow path is formed in the gap between the end face of the stator core and the first magnet, so it is extremely thin and has a higher fluid flow resistance than the first flow path. Therefore, the main flow of the fluid flows through the first flow path, so any contaminants that have been mixed in flow through the first flow path and are less likely to flow through the second flow path. This prevents the contaminants from entering the bearing. In addition, the fluid that has flowed through the first and third flow paths both flows into the fourth flow path, i.e., into the inside of the support shaft, and flows to the low-pressure region inside the housing.

[0012] In a second aspect of the present disclosure, the cylindrically formed bearing has a sliding portion against which the end surface of the bearing slides, and at least one of the end surface of the bearing and the sliding portion has a groove formed therein extending from the radial outer end to the radial inner end, and a portion of the third flow path is formed by the groove.

[0013] According to this configuration, the thrust force can be received by the bearing. In this case, the groove allows a fluid to flow between the support shaft and the bearing to lubricate the bearing.

[0014] An axial gap motor according to a third aspect of the present disclosure may include a second magnet and a second back yoke fixed to the other end of the support shaft or the other member of the bearing, and the other end face of the stator core and the second magnet may be arranged to be aligned in the direction of the rotation center line. A portion of the first flow path opposite the impeller may extend radially inward between the other end face of the stator core and the second magnet to the other end of the support shaft and be connected to the fourth flow path.

[0015] With this configuration, rotational force is generated by both the first magnet and first back yoke and the second magnet and second back yoke, thereby increasing the torque of the axial gap motor. In this case, the second magnet side of the stator core can also be cooled by the fluid flowing through the first flow path.

[0016] In a fourth aspect of the present disclosure, a cover may be provided to cover the second back yoke from the side opposite the stator core. A fifth flow passage may be formed between the second back yoke and the cover, the fifth flow passage communicating with the first flow passage and extending radially inward. The fifth flow passage may be connected to the fourth flow passage at the other end of the support shaft.

[0017] A control board that controls the axial gap motor can be disposed on the outside of the cover according to the fifth aspect of the present disclosure in contact with the cover. With this configuration, the control board can be cooled by the fluid. [Effects of the Invention]

[0018] As described above, the fluid drawn into the housing can be used to cool various parts and lubricate the bearings. If contaminants are mixed into the fluid, the contaminants will be less likely to flow between the spindle and the bearing, preventing the contaminants from entering the bearing and preventing poor rotation of the spindle. [Brief explanation of the drawings]

[0019] [Figure 1]1 is a perspective view of an electric pump according to an embodiment of the present invention; [Figure 2] 1 is a plan view of an electric pump according to an embodiment of the present invention; [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 2 is a perspective view showing a separated state of the stator assembly and the bearing before they are insert-molded into the motor housing. [Figure 5] FIG. 2 is an exploded perspective view of a stator assembly. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0021] 1 and 2 are diagrams showing the appearance of a centrifugal electric pump 1 according to an embodiment of the present invention. In this embodiment, the electric pump 1 is described as an electric water pump. Therefore, the electric pump 1 according to the embodiment of the present invention is used to circulate, through a predetermined path, coolant for cooling various devices mounted on a vehicle. Examples of the various devices include, but are not limited to, a traction motor, an inverter circuit, an engine, a transmission, and an air conditioning device. The electric pump 1 can also circulate coolant for other devices. In the description of this embodiment, the upper side of FIG. 2 will be referred to as the upper side of the electric pump 1, and the lower side of FIG. 2 will be referred to as the lower side of the electric pump 1. However, this definition is provided merely for convenience of description and does not limit the position of the electric pump 1 during actual use. The electric pump 1 may be used in any position.

[0022] In the following explanation, the present invention is described as being applied to the electric pump 1, but it is not limited to this and the present invention can also be applied to electric pumps that pump various liquids and gases. Furthermore, the electric pump that pumps gas may be a blower, fan, compressor, etc.

[0023] 2, the electric pump 1 includes an axial gap motor 2, a motor housing 3, an impeller 4 that is rotationally driven by the axial gap motor 2, a housing 5, a circuit board (control board) 6, and a back member 7. The impeller 4 is accommodated in the housing 5, and the impeller 4 accommodated in the housing 5 is rotationally driven in a predetermined direction by the axial gap motor 2.

[0024] (Configuration of housing 5) The housing 5 is an injection-molded product made, for example, by injection molding a resin material. As shown in Fig. 2, an intake pipe section 50 that protrudes in the direction of the rotation centerline of the impeller 4 is integrally molded in a central portion of the housing 5. An intake port 50a opens at the tip end (upstream end) of the intake pipe section 50. Cooling water that has flowed through an intake-side piping (not shown) is drawn into the intake port 50a.

[0025] The housing 5 has a pump chamber-forming wall 51 extending radially from the base end (downstream end) of the suction pipe 50, and is generally entirely open on the side opposite the protruding direction of the suction pipe 50. A pump chamber S1 (shown in FIG. 3) communicating with the downstream end of the suction pipe 50 is formed inside the pump chamber-forming wall 51, and the impeller 4 is housed in this pump chamber S1. As shown in FIG. 2, a bulge 51a is formed in the pump chamber-forming wall 51 at a portion radially spaced from the base end of the suction pipe 50. The bulge 51a is formed to extend in an arc around the rotation centerline of the impeller 4, and an outflow passage S2 (shown in FIG. 3) communicating with the pump chamber S1 is formed inside the bulge 51a. In other words, the electric pump 1 is configured to draw in fluid along the rotation centerline and then discharge the fluid radially as the impeller 4 rotates.

[0026] As shown in Figures 1 and 2, a discharge pipe section 52 is integrally molded in a portion of the housing 5 corresponding to the downstream end of the outflow passage S2. The discharge pipe section 52 is formed so as to protrude in a tangential direction of an imaginary circle whose center is the center of rotation of the impeller 4. The base end (upstream end) of the discharge pipe section 52 communicates with the downstream end of the outflow passage S2. A discharge port 52a (shown only in Figure 1) opens at the tip end (downstream end) of the discharge pipe section 52. The discharge port 52a communicates with a discharge-side pipe (not shown), so that the cooling water that has flowed through the discharge pipe section 52 flows into the discharge-side pipe.

[0027] (Configuration of motor housing 3) As shown in Fig. 3, the motor housing 3 is an injection-molded product made, for example, by injection molding a resin material, and is formed so as to cover the open side of the housing 5. The motor housing 3 has a stator-embedded portion 31 in which a plurality of stator cores 20 and a plurality of coils 21 that constitute the axial gap motor 2 (described later) are embedded and fixed. The stator-embedded portion 31 has a thick plate shape. The pump chamber S1 is formed between the stator-embedded portion 31 and a pump chamber-forming wall portion 51 of the housing 5.

[0028] The motor casing 3 is also provided with an annular portion 30 that is formed to fit inside the pump chamber-forming wall portion 51 of the housing 5. As shown in Fig. 4, the annular portion 30 is formed to protrude from the peripheral edge of the stator-embedded portion 31 toward the inside of the housing 5, and as shown in Fig. 3, the outer peripheral surface of the annular portion 30 and the inner peripheral surface of the pump chamber-forming wall portion 51 are in close contact with each other. By bringing the outer peripheral surface of the annular portion 30 and the inner peripheral surface of the pump chamber-forming wall portion 51 into close contact with each other, watertightness between them is ensured.

[0029] By tightly or adhesively bonding the outer peripheral surface of the annular portion 30 and the inner peripheral surface of the pump chamber-forming wall portion 51, watertightness and airtightness between them are ensured. As another joining example, the annular portion 30 and the pump chamber-forming wall portion 51 can be joined by, for example, spin welding (welding), which allows the two parts to be joined without using sealing parts such as gaskets and bolt fastening to ensure watertightness and airtightness. Alternatively, the annular portion 30 and the pump chamber-forming wall portion 51 may be joined by bolt fastening with a sealing part 300 (shown in FIG. 3) such as a gasket interposed between them, without welding or the like. The joining structure between the annular portion 30 and the pump chamber-forming wall portion 51 may be any joining structure that ensures watertightness and airtightness, so long as it is possible to use a joining structure other than the structure described above.

[0030] Reference numeral 100 in FIG. 3 denotes a bracket for mounting the electric motor 1. A cylindrical elastic member 101 made of, for example, anti-vibration rubber is attached to the tip of the bracket 100. A metal collar 102 is inserted inside the elastic member 101. The shank of a bolt B is inserted into the collar 102 and fastened to an engine or the like (not shown), thereby enabling the electric pump 1 to be floating-mounted on the engine or the like. This mounting structure is one example and can be modified as necessary. The electric pump 1 may also be mounted on the vehicle body.

[0031] (Configuration of axial gap motor 2) 3, the axial gap motor 2 includes a plurality of stator cores 20 fixed to a motor housing 3, a plurality of coils 21 wound around each of the stator cores 20, a first magnet 22A and a first back yoke 23A, a second magnet 22B and a second back yoke 23B, a rotating shaft (support shaft) 24, and a bearing 25. In FIG. 3, the impeller 4 is disposed to the right of the stator cores 20 and the coils 21, and the circuit board 6 is disposed to the left of the stator cores 20 and the coils 21.

[0032] As shown in Fig. 5, a plurality of stator cores 20 are held by one core holder 60, and a plurality of coils 21 are held by one coil holder 70. As shown in Fig. 4, a stator assembly C is formed by the plurality of stator cores 20, the plurality of coils 21, the core holder 60, and the coil holder 70.

[0033] As shown in FIG. 5 , in this example, six stator cores 20 are arranged in an annular shape around the rotation centerline, and the six stator cores 20 are spaced equally apart in the circumferential direction. The six stator cores 20 are identical, made of a metal member such as iron, and have a columnar shape that is elongated in the direction of the rotation centerline. The cross section of the stator core 20 in a direction perpendicular to the longitudinal direction is generally triangular, with the apex located closest to the rotation centerline. This cross-sectional shape is generally consistent from one longitudinal end to the other of the stator core 20. The number of stator cores 20 is not limited to six, and can be any number. Hereinafter, the number of coils 21, the shape of the core holder 60, and the shape of the coil holder 70 can be changed depending on the number of stator cores 20.

[0034] The core holder 60 has six core holding portions 61 that respectively hold the six stator cores 20 and a connecting plate portion 62 that connects the six core holding portions 61, and the core holding portions 61 and the connecting plate portion 62 are integrally molded from an electrically insulating resin material. The six core holding portions 61 correspond to the positions of the six stator cores 20 and are provided in an annular shape so as to surround the rotation center line. Each core holding portion 61 is cylindrical and is formed so as to surround the outer peripheral surface of the stator core 20. Since the core holding portions 61 are interposed between the stator core 20 and the coils 21, the stator core 20 and the coils 21 are insulated from each other by the core holding portions 61.

[0035] The connecting plate portion 62 has a disk shape and is arranged concentrically with the rotation center line. By connecting the base ends of the six annularly arranged core holding portions 61, the six core holding portions 61 are maintained at a predetermined interval. The connecting plate portion 62 has a plate-shaped first cover portion 62a that covers one end face of each stator core 20 (the end face on the right side in FIG. 3, i.e., the end face on the impeller 4 side). Since there are six stator cores 20, six first cover portions 62a are also provided at intervals from each other in the circumferential direction of the rotation center line. Each first cover portion 62a extends along one end face of the stator core 20 and has a substantially triangular shape. The core holding portion 61 is formed to protrude from the peripheral edge of the first cover portion 62a toward the other end of the stator core 20.

[0036] Each coil 21 is arranged to surround each core holding portion 61. Therefore, the coils 21 are also held by the core holder 60, but in this example, a coil holder 70 is provided to more securely hold the coils 21. That is, as shown in FIG. 5 , the coil holder 70 has a peripheral wall portion 71 that surrounds the outer periphery of the six coils 21, and an end wall portion 72. The peripheral wall portion 71 and the end wall portion 72 are integrally molded from an electrically insulating resin material. The end wall portion 72 extends in a direction perpendicular to the rotation centerline and has a plate-shaped second cover portion 72a that covers the other end face of the stator core 20 (the left end face in FIG. 3 , i.e., the end face on the side opposite the impeller 4). Each second cover portion 72a extends along the other end face of the stator core 20 and has a substantially triangular shape.

[0037] As shown in FIG. 3, a slit D is formed between the tip of the core holding portion 61 in the protruding direction and the second cover portion 72a. The formation of the slit D makes it possible to absorb dimensional variations in the parts and to allow the secondary molding resin to adhere closely to the stator core 20. The tip of the core holding portion 61 in the protruding direction may abut against the second cover portion 72a without forming the slit D. Furthermore, although not shown, a cylindrical portion shaped to cover the stator core 20 may protrude from the second cover portion 72a, and the tip of this cylindrical portion in the protruding direction may abut against the tip of the core holding portion 61 in the protruding direction. In this case, the mating surface between the cylindrical portion and the core holding portion 61 may be a surface inclined with respect to the axis of the cylindrical portion.

[0038] An opening 72b is formed in the center of the end wall portion 72, and the formation of this opening 72b increases the fluidity of the molten resin during insert molding, which will be described later.

[0039] The peripheral wall 71 protrudes from the peripheral edge of the end wall 72 along the outer periphery of the coil 21. A portion of the peripheral wall 71 is formed to bulge radially, and this radially bulging portion is formed with a wire holding portion 71a that holds the wire 21a extending from the coil 21. The radially bulging portion of the peripheral wall 71 also has an opening 71b formed therein to increase the fluidity of the molten resin during insert molding, which will be described later.

[0040] A core holder 60 that holds six stator cores 20 and has six coils 21 arranged to surround a core holding portion 61 is insert-molded into the motor housing 3. In addition, a coil holder 70 is insert-molded into the motor housing 3 while being fixed to the core holder 60. In other words, the stator assembly C is insert-molded into the motor housing 3.

[0041] That is, as shown in Fig. 5, first, the core holder 60 and the coil holder 70 are primarily molded. The resin used at this time is the primary resin. During this primary molding, it is also possible to insert-mold the six stator cores 20, in which case it is not necessary for the core holder 60 to hold the six stator cores 20. The core holder 60 and the coil holder 70 do not have to be molded at the same time, and therefore the resin for the core holder 60 and the coil holder 70 does not have to be the same.

[0042] Thereafter, the six stator cores 20 are held in the core holder 60, the coils 21 are arranged, and the core holder 60 is then assembled to the coil holder 70 to obtain the stator assembly C shown in Fig. 4. Note that in this embodiment, the stator assembly C is obtained, but the core holder 60 and the coil holder 70 do not have to be assembled, and they can also be placed separately in a secondary molding die and insert molded.

[0043] This stator assembly C is housed and positioned in a mold (not shown) for molding the motor housing 3, and after the mold is clamped, molten resin (secondary resin) is injected into the mold to perform secondary molding. After the molten resin has solidified, it is demolded to obtain the motor housing (secondary molded product) 3 with the stator assembly C insert-molded. The primary resin and secondary resin may be the same or different.

[0044] The bearing 25 can also be insert-molded. That is, when the stator assembly C is accommodated in a mold, the bearing 25 is also accommodated and positioned together. After that, the secondary molding resin hardens, and a secondary molded product is obtained in which the bearing 25 is fixed in a predetermined position in the motor housing 3.

[0045] The bearing 25 is formed in a cylindrical shape extending in the direction of the rotation centerline, and is fixed to the motor housing 3 so as to be non-rotatable, as described above. The rotating shaft 24, also shown in FIG. 3, is configured as a hollow shaft that is inserted into the bearing 25 and rotatably supported, and the length of the rotating shaft 24 is set to be longer than the length of the bearing 25. Therefore, when supported by the bearing 25, one end of the rotating shaft 24 (the end on the impeller 4 side) protrudes from the one end of the bearing 25, and the other end of the rotating shaft 24 (the end on the opposite side from the impeller 4) protrudes from the other end of the bearing 25. Although not shown, the rotating shaft 24 may be a non-rotating support shaft fixed to the motor housing 3, and the bearing 25 may be rotatably disposed relative to this support shaft.

[0046] As shown in Fig. 6, a sliding portion 24a that protrudes radially outward and extends circumferentially is formed at one end of the rotating shaft 24. The sliding portion 24a is annular. A first large diameter portion 24b is formed at a portion of the rotating shaft 24 closer to the other end than the sliding portion 24a. A small diameter portion 24c having a smaller diameter than the first large diameter portion 24b is formed at a portion of the rotating shaft 24 closer to the other end than the first large diameter portion 24b. A second large diameter portion 24d having the same diameter as the first large diameter portion 24b is formed at a portion of the rotating shaft 24 closer to the other end than the small diameter portion 24c. The sliding portion 24a may be separate from the rotating shaft 24.

[0047] An other-end prismatic section 24e is formed in a portion of the rotating shaft 24 closer to the other end than the second large-diameter section 24d. A through-hole 24f that penetrates in the radial direction is formed between the other-end prismatic section 24e and the second large-diameter section 24d of the rotating shaft 24. The rotating shaft 24 also has a one-end prismatic section 24g that protrudes in the axial direction from the sliding section 24a.

[0048] The bearing 25 shown in Fig. 7 is formed in a cylindrical shape into which the other end side of the rotating shaft 24 is inserted beyond the sliding portion 24a. One end face 25b of the bearing 25 abuts against the sliding portion 24a in the axial direction, and a groove 25c extending from the radially outer end to the radially inner end is formed in the one end face 25b. Similar to the one end face 25b, a groove 25e extending from the radially outer end to the radially inner end is also formed in the other end face 25d of the bearing 25. Furthermore, a flat surface 25a is formed on the outer peripheral surface of the bearing 25. When the bearing 25 is insert-molded, a secondary resin is molded along the flat surface 25a, which prevents the bearing 25 from rotating.

[0049] The inner diameter of bearing 25 is the same from one end face 25b side to the other end face 25d side. The outer peripheral surfaces of first large diameter portion 24b and second large diameter portion 24d of rotating shaft 24 are adapted to slide on the inner peripheral surface of bearing 25, while the outer peripheral surface of small diameter portion 24c of rotating shaft 24 is spaced apart from the inner peripheral surface of bearing 25. Although first large diameter portion 24b and second large diameter portion 24d of rotating shaft 24 are adapted to slide on the inner peripheral surface of bearing 25, a slight clearance is provided between the outer peripheral surfaces of first large diameter portion 24b and second large diameter portion 24d and the inner peripheral surface of bearing 25, allowing liquid to flow therethrough.

[0050] 3, the radial center of the impeller 4 is fixed to one end side rectangular column portion 24g that constitutes a part of one end of the rotary shaft 24. Specifically, a female thread portion is formed on the inner surface of one end of the rotary shaft 24, and the shank of a bolt E is passed through the radial center of the impeller 4 and then screwed into the female thread portion of the rotary shaft 24, thereby fastening and fixing the impeller 4 to the rotary shaft 24 so that it cannot rotate relative to the rotary shaft 24.

[0051] The first magnet 22A and the first back yoke 23A are disposed between the impeller 4 and the stator core 20, and are fixed to a surface of the impeller 4 facing the stator core 20. The first back yoke 23A is fastened together with the impeller 4 to the rotating shaft 24 by bolts E. The first magnet 22A and the first back yoke 23A are covered with a resin covering material 26. The impeller 4 is a member fixed to one end of the rotating shaft 24 so as not to be rotatable, and therefore the first magnet 22A and the first back yoke 23A fixed to the impeller 4 are also fixed to one end of the rotating shaft 24 so as not to be rotatable. With the first magnet 22A fixed to one end of the rotating shaft 24, one end face of the stator core 20 and the first magnet 22A are arranged side by side with a predetermined gap in the direction of the rotation center line.

[0052] The second magnet 22B and the second back yoke 23B are disposed on the circuit board 6 side and are fixed to an other-end side rectangular column portion 24e that constitutes the other end of the rotating shaft 24. Specifically, a female thread portion (not shown) similar to that of the one end is formed on the inner surface of the other end of the rotating shaft 24, and the shank of a bolt F is passed through the radial center of the second back yoke 23B and then screwed into the female thread portion of the rotating shaft 24, thereby fastening and fixing the second back yoke 23B to the rotating shaft 24. The second magnet 22B is fixed to the second back yoke 23B and is covered with a resin covering material 27. Therefore, the other end surface of the stator core 20 and the second magnet 22B are arranged to be aligned in the direction of the rotation center line.

[0053] A washer 28 (shown in FIG. 8) is disposed between the second back yoke 23B and the other end surface 25d of the bearing 25. The washer 28 is a component that constitutes a sliding portion on which the other end surface 25d of the bearing 25 slides. A groove (not shown) extending from the outer end to the inner end in the radial direction may be formed on the surface of the washer 28 on which the other end surface 25d of the bearing 25 slides.

[0054] A square hole 28a is formed in the washer 28, into which the square column portion 24e on the other end side of the rotating shaft 24 fits, and by fitting the square column portion 24e on the other end side into this square hole 28a, the washer 28 is prevented from rotating relative to the rotating shaft 24. Note that the washer 28 may be prevented from rotating relative to the bearing 25. On the other hand, the washer 28 and the bearing 25 are rotatable relative to each other, and the washer 28 comes into sliding contact with the other end surface 25d of the bearing 25.

[0055] The first magnet 22A and the second magnet 22B can be made of, for example, a resin magnet. The housing 5 and the secondary resin can be made of, for example, an electromagnetic shielding resin. Electromagnetic shielding resin is a resin capable of shielding electromagnetic waves and is a conventionally well-known material. For example, an electromagnetic shielding resin material obtained by blending conductive carbon fiber into a base resin material can be used. For example, a carbon fiber reinforced thermoplastic resin with polyphenylene sulfide as the base resin is suitable, but is not limited to this. On the other hand, the core holder 60, the coil holder 70, and the covering materials 26 and 27 are made of a resin that is not an electromagnetic shielding resin.

[0056] The first magnet 22A and the second magnet 22B are formed in a disk shape. The first magnet 22A and the second magnet 22B have a plurality of N-pole portions and S-pole portions alternately provided around the rotation axis 24. The positions of the first magnet 22A and the second magnet 22B relative to the stator core 20 are set so that the gap between the first magnet 22A and the second magnet 22B and the stator core 20 is as small as possible.

[0057] The first back yoke 23A and the second back yoke 23B are also formed in a disk shape and are laminated on the surfaces of the first magnet 22A and the second magnet 22B opposite the stator core 20, and are integrated with the first magnet 22A and the second magnet 22B. The outer diameters of the first back yoke 23A and the second back yoke 23B may be set to be larger than or approximately the same as the outer diameters of the first magnet 22A and the second magnet 22B.

[0058] The electric pump 1 is provided with a cover 8 that covers the second back yoke 23B from the side opposite the stator core 20. The interior space of the motor housing 3 is closed at the other end by this cover 8. The cover 8 is made of a material with high thermal conductivity, such as an aluminum alloy. A circuit board 6 for controlling the axial gap motor 2 is disposed on the outside of the cover 8 in contact with the cover 8. A heat-generating electric circuit is mounted on the circuit board 6. The circuit board 6 is covered by a back member 7. The back member 7 is fastened and fixed to the cover 8 together with the circuit board 6. The back member 7 is also made of a material with high thermal conductivity, such as an aluminum alloy.

[0059] (Flow path configuration) The electric pump 1 includes a first flow path 81, a second flow path 82, a third flow path 83, and a fourth flow path 84 as flow paths through which a fluid for cooling the coil 21, the circuit board 6, etc. and a fluid for lubricating the bearings 25 flow. The first flow path 81 is formed in the motor housing 3 and extends in a direction along the rotating shaft 24. Specifically, one end (upstream end) of the first flow path 81 communicates with a high-pressure region (outlet passage S2) formed on the impeller 4 side of the stator core 20 in the housing 5. After extending in the direction of the rotation center line to the side of the stator core 20 opposite the impeller 4, the other end (downstream end) of the first flow path 81 communicates with a space H in which the second magnet 22B and the second back yoke 23B are disposed. This space H is closed by the cover 8. The diameter of the first flow path 81 is larger than the gap formed between the first magnet 22A and the stator core 20. Furthermore, the cross-sectional shape of first flow passage 81 may be a circle, an ellipse, a polygon, or another shape. In other words, first flow passage 81 is a flow passage whose cross-sectional diameter when converted into a circle is larger than the gap formed between first magnet 22A and stator core 20.

[0060] The second flow path 82 branches off from a portion of the first flow path 81 corresponding to the gap between the first magnet 22A and the stator core 20, and extends radially inward of the axial gap motor 2 to one end of the rotating shaft 24. As described above, the gap between the first magnet 22A and the stator core 20 is set to be as narrow as possible, so the second flow path 82 is a thin flow path. In addition, the upstream end of the second flow path 82 communicates with the outflow path S2 via the upstream end of the first flow path 81.

[0061] Here, resin 400 on the outer periphery of bearing 25 continues from the radially inner end of second flow passage 82 to the flow passage between the other end face of stator core 20 and second magnet 22B. This makes it possible to prevent fluid from entering coil 21 from the bearing 25 side and second flow passage 82 side.

[0062] The third flow path 83 communicates with the radially inner portion of the second flow path 82 and extends between the rotary shaft 24 and the bearing 25 to the other end of the rotary shaft 24. That is, as described above, a slight clearance that allows fluid to flow is provided between the outer peripheral surfaces of the first large diameter portion 24b and the second large diameter portion 24d of the rotary shaft 24 and the inner peripheral surface of the bearing 25, and this clearance constitutes the third flow path 83. The gap between the outer peripheral surface of the small diameter portion 24c of the rotary shaft 24 and the inner peripheral surface of the bearing 25 is wider than the clearance, and this portion also constitutes the third flow path 83. The groove 25c formed in one end face 25b of the bearing 25 extends to the outer peripheral surface of the first large diameter portion 24b of the rotary shaft 24, and this groove 25c constitutes a part of the third flow path 83. Note that a groove (not shown) extending from the radially outer end to the inner end may be formed in the surface of the sliding portion 24a facing the bearing 25.

[0063] The fourth flow passage 84 extends inside the rotating shaft 24 in the direction of the rotation centerline. In other words, the fourth flow passage 84 is formed by taking advantage of the fact that the rotating shaft 24 is a hollow shaft. The upstream end of the fourth flow passage 84 is located at the other end of the rotating shaft 24. A bolt F that threads onto the other end of the rotating shaft 24 is formed with an intra-bolt flow passage 86 that penetrates through in the axial direction, and the fourth flow passage 84 formed inside the rotating shaft 24 communicates with the outside via this intra-bolt flow passage 86. The intra-bolt flow passage 86 communicates between the second back yoke 23B and the cover 8.

[0064] The downstream end of the fourth flow passage 84 is located at one end of the rotary shaft 24. A bolt E that is threadedly engaged with one end of the rotary shaft 24 is formed with an intra-bolt flow passage 85 that penetrates in the axial direction, and the fourth flow passage 84 formed inside the rotary shaft 24 communicates with the outside via this intra-bolt flow passage 85. The intra-bolt flow passage 85 communicates with a pump chamber S1 formed in the housing 5. The pump chamber S1 communicates with the downstream end of the suction pipe portion 50, and therefore forms a low-pressure region that is lower in pressure than the outflow passage S2. In other words, the fourth flow passage 84 communicates with the low-pressure region at one end of the rotary shaft 24.

[0065] A portion of the first flow passage 81 opposite the impeller 4 (a portion constituting the downstream side) extends radially inward between the other end face of the stator core 20 and the second magnet 22B to the other end of the rotary shaft 24. The downstream end of the first flow passage 81 communicates with a space H in which the second magnet 22B and the second back yoke 23B are disposed. The space H communicates with a groove 25e formed in the other end face 25d of the bearing 25. The groove 25e in the other end face 25d of the bearing 25 communicates with the fourth flow passage 84. That is, the downstream end of the first flow passage 81 is connected to the fourth flow passage 84 at the other end of the rotary shaft 24 via the space H in which the second magnet 22B and the second back yoke 23B are disposed, the groove 25e in the other end face 25d of the bearing 25, and the through-hole 24f.

[0066] Furthermore, the third flow path 83 extends to the other end of the rotary shaft 24 and is therefore connected to the groove 25e in the other end face 25d of the bearing 25. Therefore, the third flow path 83 is also connected to the fourth flow path 84 at the other end of the rotary shaft 24.

[0067] Furthermore, a fifth flow path H1 that communicates with a downstream portion of the first flow path 81 and extends radially inward is formed between the second back yoke 23B and the cover 8. The fifth flow path H1 is configured as a part of the space H in which the second magnet 22B and the second back yoke 23B are disposed. The fifth flow path H1 is connected to the fourth flow path 84 via an in-bolt flow path 86 at the other end of the rotating shaft 24.

[0068] (Effects of the embodiment) As described above, according to this embodiment, when the impeller 4 is rotated by the axial gap motor 2, the fluid in the housing 5 is sucked in near the rotation center line of the impeller 4 and discharged radially outward. Therefore, a low-pressure region near the rotation center line of the impeller 4 and a high-pressure region radially outward from the impeller 4 are formed inside the housing 5. Since the first flow path 81 is connected to the high-pressure region, part of the fluid in the high-pressure region flows into the first flow path 81 and flows to the side of the stator core 20 opposite the impeller 4. The fluid flowing through this first flow path 81 cools the stator core 20 and the like. In addition, the fluid also flows into the second flow path 82 branching from the first flow path 81, and the fluid flows through the third flow path 83, thereby enabling lubrication and cooling of the bearings 25.

[0069] At this time, the second flow passage 82 is formed in the gap between the end face of the stator core 20 and the first magnet 22A, and therefore has an extremely thin shape, resulting in a greater fluid flow resistance than the first flow passage 81. Therefore, the main flow of the fluid flows through the first flow passage 81, and contaminants that have been mixed in flow through the first flow passage 81 and are less likely to flow through the second flow passage 82. This prevents contaminants from entering the bearing 25. Furthermore, the fluids that have flowed through the first flow passage 81 and the third flow passage 83 both flow from the groove 25e on the other end face 25d of the bearing 25 through the through-hole 24f of the rotating shaft 24 and into the fourth flow passage 84. The fluid that has flowed into the fourth flow passage 84 flows to the low-pressure region within the housing 5. Furthermore, the fluid that has flowed through the first flow passage 81 may also flow directly into the fourth flow passage 84 from the in-bolt flow passage 86.

[0070] In addition, the fluid also flows between the stator core 20 and the second magnet 22B, which cools the second magnet 22B side of the stator core 20. Furthermore, the fluid also flows between the cover 8 and the second back yoke 23B, which cools the circuit board 6 via the cover 8.

[0071] The above-described embodiments are merely examples in all respects and should not be construed as limiting. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention. [Industrial Applicability]

[0072] As described above, the electric pump according to the present invention can be applied to, for example, an electric water pump mounted on an automobile. [Explanation of symbols]

[0073] 1 electric pump 2 Axial gap motor 3 Motor housing 4 impellers 5. Housing 6 Circuit board (control board) 8 Cover 20 stator core 21 Coil 22A First Magnet 23A 1st Back Yoke 24 Rotating shaft (support shaft) 25 bearings 81 First Channel 82 Second Channel 83 Third Channel 84 4th Channel H1 5th flow path

Claims

1. A centrifugal electric pump including an impeller that is rotationally driven by an axial gap motor and a housing that accommodates the impeller, The axial gap motor includes a stator core fixed to a motor housing and a coil wound around the stator core, a first magnet and a first back yoke fixed to the impeller, a support shaft consisting of a hollow shaft, and a bearing that receives the support shaft, one of the support shaft and the bearing is fixed to the motor housing, the other is rotatable relative to the one member, the impeller is fixed to one end of the other member, and one end face of the stator core and the first magnet are arranged side by side with a predetermined gap in the direction of the rotation center line, a first flow path that communicates with a high-pressure region formed on the impeller side of the stator core in the housing, extends in the direction of the rotation center line to a side of the stator core opposite to the impeller, and has a cross-sectional diameter, when converted into a circle, larger than that of the gap; a second flow path branching from the first flow path and extending through the gap toward the inside in the radial direction of the motor to one end of the support shaft; a third flow path that communicates with the radially inner portion of the second flow path and extends between the support shaft and the bearing to the other end of the support shaft; a fourth flow path extending in the direction of the rotation center line inside the support shaft; a sliding portion formed in a cylindrical shape on which an end surface of the bearing slides; a second magnet and a second back yoke fixed to the other end of the other member of the support shaft or the bearing; a cover that covers the second back yoke from the side opposite to the stator core, The other end surface of the stator core and the second magnet are arranged to be aligned in the direction of the rotation center line, the third flow path is formed by a clearance between an outer peripheral surface of the support shaft and an inner peripheral surface of the bearing, a portion of the first flow path opposite to the impeller and a portion of the third flow path on the other end side of the support shaft are connected to the fourth flow path at the other end of the support shaft, the fourth flow path communicates with a low-pressure region formed within the housing at one end of the support shaft; a groove extending from a radially outer end to an inner end is formed in at least one of an end surface of the bearing and the sliding portion, and a part of the third flow path is formed by the groove; A fifth flow path is formed between the second back yoke and the cover, the fifth flow path being in communication with the first flow path and extending radially inward, the fifth flow path is connected to the fourth flow path at the other end of the support shaft, The electric pump is characterized in that a control board for controlling the axial gap motor is disposed outside the cover in contact with the cover.

2. The electric pump according to claim 1, an electric pump, characterized in that a portion of the first flow path opposite the impeller extends radially inward between the other end face of the stator core and the second magnet to the other end of the support shaft and is connected to the fourth flow path.

Images